LMH2120 www.ti.com SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 LMH2120 6 GHz Linear RMS Power Detector with 40 dB Dynamic Range Check for Samples: LMH2120 FEATURES DESCRIPTION * * * * * * * * * * The LMH2120 is a 40 dB Linear RMS power detector particularly suited for accurate power measurement of modulated RF signals that exhibit large peak-toaverage ratios, i.e, large variations of the signal envelope. Such signals are encountered in W-CDMA and LTE cell phones. The RMS measurement topology inherently ensures a modulation insensitive measurement. 1 2 Linear Root Mean Square Response 40 dB Linear-in-V Power Detection Range Multi-Band Operation from 50 MHz to 6 GHz Lin Conformance Better than 0.5 dB Highly Temperature Insensitive Modulation Independent Response Minimal Slope and Intercept Variation Shutdown Functionality Wide Supply Range from 2.7V to 5V Tiny 6-Bump DSBGA Package APPLICATIONS * * Multi Mode, Multi Band RF Power Control - GSM/EDGE - CDMA/CDMA2000 - W-CDMA - OFDMA - LTE Infrastructure RF Power Control The device has an RF frequency range from 50 MHz to 6 GHz. It provides an accurate, temperature and supply insensitive, output voltage that relates linearly to the RF input power in volt. The LMH2120's excellent conformance to a linear response enables an easy integration by using slope and intercept only, reducing calibration effort significantly. The device operates with a single supply from 2.7V to 5V. The LMH2120 has an RF power detection range from -35 dBm to 5 dBm and is ideally suited for use in combination with a directional coupler. Alternatively, a resistive divider can be used. The device is active for EN = High, otherwise it is in a low power consumption shutdown mode. To save power and prevent discharge of an external filter capacitance, the output (OUT) is high impedance during shutdown. The LMH2120 power detector is offered in a tiny 6bump DSBGA package. 10 RF COUPLER ANTENNA PA 1 VOUT (V) 50: VDD 0.1 A1 RFIN B1 A2 OUT LMH2120 EN 85C 25C C2 ADC 0.01 -50 -40C -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) C1, B2 GND Figure 1. Typical Application Figure 2. Output Voltage vs. RF Input Power at 1900 MHz 1 2 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright (c) 2010-2013, Texas Instruments Incorporated LMH2120 SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 www.ti.com These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. Absolute Maximum Ratings (1) (2) Supply Voltage VDD - GND 5.5V RF Input Input power 12 dBm DC Voltage 1V Enable (EN) Input Voltage ESD Tolerance GND-0.4V < VEN and VEN<Min (VDD+0.4, 3.6V) (3) Human Body Model 2000V Machine Model 200V Charge Device Model 1000V -65C to 150C Storage Temperature Range Junction Temperature (4) 150C For soldering specifications: See product folder at www.ti.com and SNOA549 (1) (2) (3) (4) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not ensured. For ensured specifications and the test conditions, see the Electrical Characteristics. If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications. Human body model, applicable std. MIL-STD-883, Method 3015.7. Machine model, applicable std. JESD22-A115-A (ESD MM std of JEDEC). Field-Induced Charge-Device Model, applicable std. JESD22-C101-C. (ESD FICDM std. of JEDEC) The maximum power dissipation is a function of TJ(MAX) , JA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(MAX) - TA)/JA. All numbers apply for packages soldered directly into a PC board. Operating Ratings (1) Supply Voltage 2.7V to 5V -40C to +85C Temperature Range RF Frequency Range 50 MHz to 6 GHz -35 dBm to 5 dBm RF Input Power Range Package Thermal Resistance JA (2) (1) (2) 2 166.7C/W Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not ensured. For ensured specifications and the test conditions, see the Electrical Characteristics. The maximum power dissipation is a function of TJ(MAX) , JA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(MAX) - TA)/JA. All numbers apply for packages soldered directly into a PC board. Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 LMH2120 www.ti.com SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 2.7 V and 4.5V DC and AC Electrical Characteristics Unless otherwise specified, all limits are ensured to TA = 25C, VDD = 2.7V and 4.5V (worst case of the 2 is specified), RFIN= 1900 MHz CW (Continuous Wave, unmodulated). Boldface limits apply at the temperature extremes (1). Symbol Parameter Condition Min Typ Max Units 2.9 3.5 4.0 mA VBAT = 2.7V 3.8 4.7 5.0 VBAT = 4.5V 4.7 5.7 6.1 VBAT = 2.7V 3.8 4.7 5.0 VBAT = 4.5V 4.7 5.7 6.1 (2) (3) (2) Supply Interface IDD Supply Current Active mode: EN = High, no signal present at RFIN. Shutdown: EN = LOW, no signal present at RFIN EN = LOW, RFIN = 0 dBm, 1900 MHz PSRR Power Supply Rejection Ratio RFIN = -10 dBm, 1900 MHz, 2.7V < VBAT < 5V 50 A A 60 dB Logic Enable Interface VLOW EN logic LOW input level (Shutdown mode) VHIGH EN logic HIGH input level IEN Current into EN pin 0.6 V 1.1 50 nA 50 56 18 29 33 mV 1 2 3 Input / Output Interface RIN Input Resistance VOUT Minimum Output Voltage (Pedestal) No Input Signal 44 ROUT Output Resistance EN = HIGH, RFIN = -10 dBm, 1900 MHz, ILOAD = 1 mA, DC measurement IOUT Output Sinking Current RFIN = -10 dBm, 1900 MHz, OUT connected to 2.5V 30 25 42 Output Sourcing Current RFIN = -10 dBm, 1900 MHz, OUT connected to GND 36 31 45 IOUT, SD Output Leakage Current in Shutdown Mode EN = LOW, OUT connected to 2V en Output Referred Noise vn Output Referred Noise Integrated (4) (4) RFIN = -10 dBm, 1900 MHz, output spectrum at 10 kHz mA 80 nA 5 V/Hz Integrated over frequency band 1 kHz 6.5 kHz, RFIN = -10 dBm, 1900 MHz 390 VRMS Timing Characteristics tON Turn-on Time from shutdown RFIN = -10 dBm, 1900 MHz, EN LOWto-HIGH transition to OUT at 90% 13 tR Rise Time Signal at RFIN from -20 dBm to 0 dBm, 10% to 90%, 1900 MHz 7 s tF Fall Time Signal at RFIN from 0 dBm to -20 dBm, 90% to 10%, 1900 MHz 18 s (1) (2) (3) (4) 18 s Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating of the device such that TJ = TA. No specification of parametric performance is indicated in the electrical tables under conditions of internal self-heating where TJ > TA. All limits are ensured by test or statistical analysis. Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary over time and will also depend on the application and configuration. The typical values are not tested and are not specified on shipped production material. This parameter is ensured by design and/or characterization and is not tested in production. Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 3 LMH2120 SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 www.ti.com 2.7 V and 4.5V DC and AC Electrical Characteristics (continued) Unless otherwise specified, all limits are ensured to TA = 25C, VDD = 2.7V and 4.5V (worst case of the 2 is specified), RFIN= 1900 MHz CW (Continuous Wave, unmodulated). Boldface limits apply at the temperature extremes (1). Symbol Parameter Condition Min Typ (2) (3) Max (2) Units RF Detector Transfer, fit range -15 dBm to -5 dBm for Linear Slope and Intercept RFIN = 50 MHz (5) PMIN Minimum Power Level, bottom end of Dynamic Range PMAX Maximum Power Level, top end of Dynamic Range VMIN Minimum Output Voltage At PMIN 31 mV VMAX Maximum Output Voltage At PMAX 2.6 V KSLOPE Linear Slope PINT Linear Intercept VOUT = 0 dBV DR Dynamic Range for specified Accuracy RFIN = 900 MHz Log Conformance Error within 1 dB -37 dBm 4 1 -5.7 -5.5 1 dB Lin Conformance Error (ELC) 37 36 41 40 3 dB Lin Conformance Error (ELC) 44 43 48 47 0.5 dB Variation over Temperature (EVOT) 41 45 dB/dB -5.3 dBm dB (5) PMIN Minimum Power Level, bottom end of Dynamic Range PMAX Maximum Power Level, top end of Dynamic Range VMIN Minimum Output Voltage At PMIN 33 VMAX Maximum Output Voltage At PMAX 2.5 V KSLOPE Linear Slope 1 dB/dB PINT Linear Intercept VOUT = 0 dBV DR Dynamic Range for specified Accuracy EMOD Input referred Variation due to Modulation Lin Conformance Error within 1 dB -35 dBm 5 -4.2 -4.0 1 dB Lin Conformance Error (ELC) 36 33 40 37 3 dB Lin Conformance Error (ELC) 45 44 48 47 0.5 dB Variation over Temperature (EVOT) 41 44 0.3 dB Error for a 1dB Power Step (E1dB) 41 40 1 dB Error for a 10dB Power Step (E10dB) 45 W-CDMA Release 6/7/8, -35 dBm<RFIN<-3 dBm 0.15 LTE, -35 dBm<RFIN<-3 dBm 0.29 mV -3.8 dBm dB dB RFIN = 1900 MHz (5) PMIN Minimum Power Level, bottom end of Dynamic Range PMAX Maximum Power Level, top end of Dynamic Range VMIN Minimum Output Voltage At PMIN 30 VMAX Maximum Output Voltage At PMAX 1.7 V KSLOPE Linear Slope 1 dB/dB PINT Linear Intercept (5) 4 Lin Conformance Error within 1 dB -34 dBm 4 VOUT = 0 dBV -2.2 -1.8 mV -1.4 dBm Limits are ensured by design and measurements which are performed on a limited number of samples. Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 LMH2120 www.ti.com SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 2.7 V and 4.5V DC and AC Electrical Characteristics (continued) Unless otherwise specified, all limits are ensured to TA = 25C, VDD = 2.7V and 4.5V (worst case of the 2 is specified), RFIN= 1900 MHz CW (Continuous Wave, unmodulated). Boldface limits apply at the temperature extremes (1). Symbol DR Parameter Dynamic Range for specified Accuracy EMOD Input referred Variation due to Modulation Condition Min Typ 1 dB Lin Conformance Error (ELC) 35 31 38 35 3 dB Lin Conformance Error (ELC) 44 41 48 45 0.5 dB Variation over Temperature (EVOT) 35 40 (2) (3) 0.3 dB Error for a 1dB Power Step (E1dB) 39 36 1 dB Error for a 10dB Power Step (E10dB) 35 W-CDMA Release 6/7/8, -34 dBm<RFIN<-2 dBm 0.16 LTE, -34 dBm<RFIN<-2 dBm 0.24 Max (2) Units dB dB RFIN = 2600 MHz (5) PMIN Minimum Power Level, bottom end of Dynamic Range Lin Conformance Error within 1 dB PMAX Maximum Power Level, top end of Dynamic Range VMIN Minimum Output Voltage At PMIN 31 VMAX Maximum Output Voltage At PMAX 1.5 V KSLOPE Linear Slope 1 dB/dB PINT Linear Intercept VOUT = 0 dBV 0.8 1.7 DR Dynamic Range for specified Accuracy 1 dB Lin Conformance Error (ELC) 32 29 36 33 3 dB Lin Conformance Error (ELC) 43 40 45 42 0.5 dB Variation over Temperature (EVOT) 34 39 -30 dBm 6 mV 2.6 dBm dB RFIN = 3500 MHz (6) PMIN Minimum Power Level, bottom end of Dynamic Range PMAX Maximum Power Level, top end of Dynamic Range VMIN Minimum Output Voltage At PMIN 32 VMAX Maximum Output Voltage At PMAX 1.1 V KSLOPE Linear Slope 1 dB/dB PINT Linear Intercept VOUT = 0 dBV 4.4 5.5 DR Dynamic Range for specified Accuracy 1 dB Lin Conformance Error (ELC) 30 27 33 30 3 dB Lin Conformance Error (ELC) 39 36 42 40 0.5 dB Variation over Temperature (EVOT) 27 35 (6) Lin Conformance Error within 1 dB -26 dBm 7 mV 6.7 dBm dB Limits are ensured by design and measurements which are performed on a limited number of samples. Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 5 LMH2120 SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 www.ti.com CONNECTION DIAGRAM VDD A1 A2 OUT RFIN B1 B2 GND GND C1 C2 EN Figure 3. 6-Bump DSBGA Top View PIN DESCRIPTIONS Power Supply DSBGA Name A1 VDD Positive Supply Voltage. GND Ground. Both C1 and B2 need to be connected to GND. C1 B2 Description Logic Input C2 EN The device is enabled for EN = High, and in shutdown mode for EN = LOW. EN should be <2.5V when IEN is LOW. For EN >2.5V, IEN increases slightly while the device is still functional. Absolute maximum rating for EN = 3.6V. Analog Input B1 RFIN RF input signal to the detector, internally terminated with 50 . Output A2 OUT Ground referenced detector output voltage. BLOCK DIAGRAM A1 VDD LDO V/I B1 Internal Supply V/I RFIN OUT A2 A C2 EN V/I V/I GND C1, B2 Figure 4. LMH2120 6 Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 LMH2120 www.ti.com SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 Typical Performance Characteristics Unless otherwise specified TA = 25C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors are input referred. Supply Current vs. Supply Voltage (Active) 5 Supply Current vs. Supply Voltage (Shutdown) 8 EN = LOW EN = HIGH 4 SUPPLY CURRENT (eA) SUPPLY CURRENT (mA) 7 3 2 85C 25C -40C 1 6 5 4 85C 3 25C 2 1 -40C 0 0 1 2 3 4 5 0 0 6 1 2 5 6 Figure 6. Supply Current vs. Enable Voltage (EN) Supply Current vs. RF Input Power 6 5 4 85C 3 25C 2 -40C 1 4 3 2 85C 25C -40C 1 0 0.5 0.6 0.7 0.8 0.9 1.0 1.1 0 -50 1.2 ENABLE VOLTAGE (V) -30 -20 -10 0 10 Figure 7. Figure 8. Output Sourcing Current vs. RF Input Power Output Sinking Current vs. RF Input Power 40 -40C 25C 30 85C 20 10 OUT = 0V RFin = 1900 MHz -40 -30 -20 -10 0 OUTPUT SINKING CURRENT (mA) 60 50 0 -50 -40 RF INPUT POWER (dBm) 60 OUTPUT SOURCING CURRENT (mA) 4 Figure 5. SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) 5 3 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) 10 RF INPUT POWER (dBm) 50 40 25C 30 -40C 85C 20 10 0 -50 OUT = 2.5V RFin = 1900 MHz -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 9. Figure 10. Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 7 LMH2120 SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 www.ti.com Typical Performance Characteristics (continued) Unless otherwise specified TA = 25C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors are input referred. RF Input Impedance vs. Frequency, Resistance (R) and Reactance (X) Power Supply Rejection Ratio vs. Frequency 70 100 75 100 50 75 50 25 25 0 0 -25 -25 -50 60 70 PSRR (dB) RF INPUT IMPEDANCE (O) R X -75 -50 -100 60 50 50 40 40 30 30 20 20 10 0 10 -75 MEASURED ON BUMP -100 10M 100M 1G 0 10G 10 100 10k Figure 11. Figure 12. Output Voltage Noise vs. Frequency Lin Slope vs. Frequency 8 100k 1.3 PIN = -10 dBm OUTPUT VOLTAGE NOISE (PV/ Hz) 1k FREQUENCY (Hz) FREQUENCY (Hz) 7 1.2 LIN SLOPE (dB/dB) 6 5 4 3 2 -40C 1.0 85C 25C 0.9 0.8 1 0 10 1.1 100 1k 10k 100k 0.7 10M 1M 100M 1G 10G FREQUENCY (Hz) FREQUENCY (Hz) Figure 13. Figure 14. Lin Intercept vs. Frequency Output Voltage vs. RF Input Power 10 12 10 3.5 GHz 6 2.6 GHz 1 VOUT (V) LIN INTERCEPT (dBm) 8 4 2 0 1.9 GHz 900 MHz 0.1 -2 25C 50 MHz 85C 5.8 GHz -4 -40C -6 -8 10M 100M 1G 0.01 -50 10G FREQUENCY (Hz) -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 15. 8 -40 Figure 16. Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 LMH2120 www.ti.com SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 Typical Performance Characteristics (continued) Unless otherwise specified TA = 25C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors are input referred. Output Voltage vs. Frequency Output Voltage vs. RF Input Power at 50 MHz 10 10 RFIN = 0 dBm RFIN = -5 dBm 1 RFIN = -10 dBm VOUT (V) VOUT (V) 1 RFIN = -15 dBm RFIN = -20 dBm RFIN = -25 dBm 0.1 0.1 RFIN = -30 dBm RFIN = -35 dBm 0.01 85C 25C RFIN = -40 dBm 10M 100M 1G 0.01 -50 10G -40C -40 -30 Figure 17. 2 85C -40C 1 0 25C -1 -40C 1 ERROR (dB) ERROR (dB) 10 3 2 0 -1 -2 85C -2 -40 -30 -20 -10 0 -3 -50 10 -40 RF INPUT POWER (dBm) -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 19. Figure 20. Temperature Variation vs. RF Input Power at 50 MHz Temperature Variation (50 units) vs. RF Input Power at 50 MHz 2.0 2.0 1.5 1.5 1.0 1.0 -40C 0.5 ERROR (dB) ERROR (dB) 0 Lin Conformance (50 units) vs. RF Input Power at 50 MHz 3 0.0 -0.5 85C 0.0 -0.5 85C -1.0 -1.5 -1.5 -40 -30 -20 -10 -40C 0.5 -1.0 -2.0 -50 -10 Figure 18. Lin Conformance vs. RF Input Power at 50 MHz -3 -50 -20 RF INPUT POWER (dBm) FREQUENCY (Hz) 0 10 -2.0 -50 RF INPUT POWER (dBm) -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 21. Figure 22. Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 9 LMH2120 SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 www.ti.com Typical Performance Characteristics (continued) Unless otherwise specified TA = 25C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors are input referred. Output Voltage vs. RF Input Power at 900 MHz Lin Conformance vs. RF Input Power at 900 MHz 10 3 2 VOUT (V) 0.1 0 25C -1 85C 25C 0.01 -50 -40C 1 ERROR (dB) 1 85C -2 -40C -40 -30 -20 -10 0 -3 -50 10 -40 RF INPUT POWER (dBm) -20 -10 0 10 Figure 23. Figure 24. Lin Conformance (50 units) vs. RF Input Power at 900 MHz Temperature Variation vs. RF Input Power at 900 MHz 3 2.0 1.5 2 1.0 -40C -40C ERROR (dB) 1 ERROR (dB) -30 RF INPUT POWER (dBm) 0 -1 85C 0.5 0.0 -0.5 85C -1.0 -2 -1.5 -3 -50 -40 -30 -20 -10 0 -2.0 -50 10 -40 -20 -10 0 10 Figure 25. Figure 26. Temperature Variation (50 units) vs. RF Input Power at 900 MHz 1 dB Power Step Error vs. RF Input Power at 900 MHz 2.0 1.5 1.5 1.2 0.9 1.0 -40C 0.6 0.5 ERROR (dB) ERROR (dB) -30 RF INPUT POWER (dBm) RF INPUT POWER (dBm) 0.0 -0.5 85C 85C 0.3 0.0 -0.3 25C -0.6 -1.0 -40C -0.9 -1.5 -2.0 -50 -1.2 -40 -30 -20 -10 0 10 -1.5 -50 RF INPUT POWER (dBm) -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 27. 10 -40 Figure 28. Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 LMH2120 www.ti.com SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 Typical Performance Characteristics (continued) Unless otherwise specified TA = 25C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors are input referred. W-CDMA variation vs. RF Input Power at 900 MHz 10 dB Power Step Error vs. RF Input Power at 900 MHz 1.5 2.0 1.5 1.0 1.0 ERROR (dB) ERROR (dB) 85C 0.5 0.0 -0.5 W-CDMA, REL8 0.5 0.0 W-CDMA, REL6 -0.5 -40C W-CDMA, REL7 -1.0 -1.0 -1.5 -2.0 -50 -40 -30 -20 -10 -1.5 -50 0 -40 RF INPUT POWER (dBm) 1.5 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 29. Figure 30. LTE variation vs. RF Input Power at 900 MHz Output Voltage vs. RF Input Power at 1900 MHz 10 20 MHz, 100 RB 0.5 1 LTE, QPSK VOUT (V) ERROR (dB) 1.0 0.0 0.1 -0.5 85C LTE, 16 QAM 25C -1.0 LTE, 64 QAM -1.5 -50 -40 -30 -20 -10 0 0.01 -50 10 -40C -40 -10 0 10 Figure 31. Figure 32. Lin Conformance vs. RF Input Power at 1900 MHz Lin Conformance (50 units) vs. RF Input Power at 1900 MHz 3 3 2 2 1 85C 25C 0 -40C -1 85C 1 0 -1 -2 -3 -50 -20 RF INPUT POWER (dBm) ERROR (dB) ERROR (dB) RF INPUT POWER (dBm) -30 -40C -2 -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) -3 -50 -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 33. Figure 34. Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 11 LMH2120 SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 www.ti.com Typical Performance Characteristics (continued) Unless otherwise specified TA = 25C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors are input referred. Temperature Variation vs. RF Input Power at 1900 MHz 2.0 1.5 1.5 1.0 1.0 85C 85C ERROR (dB) ERROR (dB) Temperature Variation (50 units) vs. RF Input Power at 1900 MHz 2.0 0.5 0.0 -0.5 0.5 0.0 -0.5 -40C -40C -1.0 -1.0 -1.5 -1.5 -2.0 -50 -40 -30 -20 -10 0 -2.0 -50 10 -40 -30 RF INPUT POWER (dBm) 1 dB Power Step Error vs. RF Input Power at 1900 MHz 10 dB Power Step Error vs. RF Input Power at 1900 MHz 2.0 1.2 1.5 10 1.0 85C ERROR (dB) 0.6 ERROR (dB) 0 Figure 36. 1.5 85C 0.3 0.0 -0.3 0.5 0.0 -0.5 25C -0.6 -40C -1.0 -40C -0.9 -1.5 -1.2 -1.5 -50 -40 -30 -20 -10 0 -2.0 -50 10 -40 -30 -10 Figure 37. Figure 38. W-CDMA variation vs. RF Input Power at 1900 MHz LTE variation vs. RF Input Power at 1900 MHz 1.5 1.5 1.0 1.0 ERROR (dB) W-CDMA, REL8 0.5 0.0 W-CDMA, REL6 -0.5 0.5 LTE, QPSK 0.0 -0.5 -1.0 LTE, 16 QAM -1.0 -40 -30 -20 -10 0 20 MHz, 100 RB W-CDMA, REL7 -1.5 -50 -20 RF INPUT POWER (dBm) RF INPUT POWER (dBm) ERROR (dB) -10 Figure 35. 0.9 0 10 RF INPUT POWER (dBm) -1.5 -50 LTE, 64 QAM -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 39. 12 -20 RF INPUT POWER (dBm) Figure 40. Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 LMH2120 www.ti.com SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 Typical Performance Characteristics (continued) Unless otherwise specified TA = 25C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors are input referred. Output Voltage vs. RF Input Power at 2600 MHz Lin Conformance vs. RF Input Power at 2600 MHz 10 3 2 VOUT (V) ERROR (dB) 1 0.1 85C 1 0 -40C -1 85C 25C 0.01 -50 25C -2 -40C -40 -30 -20 -10 0 -3 -50 10 -40 RF INPUT POWER (dBm) -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 41. Figure 42. Lin Conformance (50 units) vs. RF Input Power at 2600 MHz Temperature Variation vs. RF Input Power at 2600 MHz 2.0 3 1.5 2 85C ERROR (dB) ERROR (dB) 1.0 85C 1 0 -1 0.5 0.0 -0.5 -40C -40C -1.0 -2 -1.5 -3 -50 -40 -30 -20 -10 0 -2.0 -50 10 -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) RF INPUT POWER (dBm) Figure 43. Figure 44. Temperature Variation (50 units) vs. RF Input Power at 2600 MHz Output Voltage vs. RF Input Power at 3500 MHz 10 2.0 1.5 85C 1 0.5 VOUT (V) ERROR (dB) 1.0 0.0 -0.5 0.1 -40C -1.0 85C 25C -1.5 -40C -2.0 -50 -40 -30 -20 -10 0 0.01 -50 10 -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) RF INPUT POWER (dBm) Figure 45. Figure 46. Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 13 LMH2120 SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 www.ti.com Typical Performance Characteristics (continued) Unless otherwise specified TA = 25C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors are input referred. Lin Conformance vs. RF Input Power at 3500 MHz Lin Conformance (50 units) vs. RF Input Power at 3500 MHz 3 3 2 85C 1 0 -40C -1 85C 1 ERROR (dB) ERROR (dB) 2 0 -1 25C -40C -2 -2 -3 -50 -40 -30 -20 -10 0 -3 -50 10 -40 RF INPUT POWER (dBm) -20 Temperature Variation vs. RF Input Power at 3500 MHz Temperature Variation (50 units) vs. RF Input Power at 3500 MHz 2.0 1.5 1.0 85C 85C ERROR (dB) 0.5 0.0 -0.5 0.5 0.0 -0.5 -40C -1.0 -1.0 -1.5 -1.5 -40 -30 -20 -10 0 10 -40C -2.0 -50 -40 RF INPUT POWER (dBm) -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 49. Figure 50. Output Voltage vs. RF Input Power at 5800 MHz Lin Conformance vs. RF Input Power at 5800 MHz 3 2 VOUT (V) ERROR (dB) 1 0.1 85C 1 0 -40C -1 25C 0.01 -50 85C -40C -40 25C -2 -30 -20 -10 0 10 RF INPUT POWER (dBm) -3 -50 -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 51. 14 10 Figure 48. 1.5 10 0 RF INPUT POWER (dBm) 2.0 -2.0 -50 -10 Figure 47. 1.0 ERROR (dB) -30 Figure 52. Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 LMH2120 www.ti.com SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 Typical Performance Characteristics (continued) Unless otherwise specified TA = 25C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors are input referred. Temperature Variation vs. RF Input Power at 5800 MHz 2.0 1.5 1.0 ERROR (dB) 85C 0.5 0.0 -0.5 -40C -1.0 -1.5 -2.0 -50 -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 53. Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 15 LMH2120 SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 www.ti.com APPLICATION INFORMATION The LMH2120 is a 40 dB Linear RMS power detector particularly suited for accurate power measurements of modulated RF signals that exhibit large peak-to-average ratios (PAR's). The RMS detector implements the exact definition of power resulting in a power measurement insensitive to high PAR's. Such signals are encountered, e.g, in LTE and W-CDMA applications. The LMH2120 has an RF frequency range from 50 MHz to 6 GHz. It provides an output voltage that relates linearly to the RF input power in volt. Its output voltage is highly insensitive to temperature and supply variations. TYPICAL APPLICATION The LMH2120 can be used in a wide variety of applications like LTE, W-CDMA, CDMA and GSM. This section discusses the LMH2120 in a typical transmit power control loop for such applications. Transmit-power-control-loop circuits make the transmit-power level insensitive to power amplifier (PA) inaccuracy. This is desirable because power amplifiers are non-linear devices and temperature dependent, making it hard to estimate the exact transmit power level. If a control loop is used, the inaccuracy of the PA is eliminated from the overall accuracy of the transmit power level. The accuracy of the transmit power level now depends on the RF detector accuracy instead. The LMH2120 is especially suited for transmit-power control applications, since it accurately measures transmit power and is insensitive to temperature, supply voltage and modulation variations. Figure 54 shows a simplified schematic of a typical transmit-power control system. The output power of the PA is measured by the LMH2120 through a directional coupler. The measured output voltage of the LMH2120 is digitized by the ADC inside the baseband chip. Accordingly, the baseband controls the PA output power level by changing the gain control signal of the RF VGA. Although the output ripple of the LMH2120 is typically low enough, an optional low-pass filter can be placed in between the LMH2120 and the ADC to further reduce the ripple. COUPLER RF PA VGA ANTENNA B A S E B A N D 50: GAIN VDD OPTIONAL RS ADC OUT CS A1 A2 RFIN B1 LMH2120 EN EN C2 B2, C1 GND Figure 54. Transmit-Power Control System ACCURATE POWER MEASUREMENT Detectors have evolved over the years along with the communication standards. Newer communication standards like LTE and W-CDMA raise the need for more advanced accurate power detectors. To be able to distinguish the various detector types it is important to understand what the ideal power measurement should look like and how a power measurement is implemented. Power is a metric for the average energy content of a signal. By definition it is not a function of the signal shape over time. In other words, the power content of a 0 dBm sine wave is identical to the power content of a 0 dBm square wave or a 0 dBm W-CDMA signal; all these signals have the same average power content. The average power can be described by the following formula: 16 Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 LMH2120 www.ti.com 1 P= T SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 T 0 2 VRMS v(t) dt = R R 2 (1) where T is the time interval over which is averaged, v(t) is the instantaneous voltage at time t, R is the resistance in which the power is dissipated, and VRMS is the equivalent RMS voltage. According to aforementioned formula for power, an exact power measurement can be done by measuring the RMS voltage (VRMS) of a signal. The RMS voltage is described by: VRMS = 2 1 v(t) dt T (2) Implementing the exact formula for RMS can be difficult however. A simplification can be made in determining the average power when information about the waveform is available. If the signal shape is known, the relationship between RMS value and, for instance, the peak value of the RF signal is also known. It thus enables a measurement based on measuring peak voltage rather than measuring the RMS voltage. To calculate the RMS value (and therewith the average power), the measured peak voltage is translated into an RMS voltage based on the waveform characteristics. A few examples: * Sine wave: VRMS = VPEAK / 2 * Square wave: VRMS = VPEAK * Saw-tooth wave: VRMS = VPEAK / 3 For more complex waveforms it is not always easy to determine the exact relationship between RMS value and peak value. A peak measurement can therefore become impractical. An approximation can be used for the VRMS to VPEAK relationship, but it can result in a less accurate average power estimate. Depending on the detection mechanism, power detectors may produce a slightly different output signal in response to the earlier mentioned waveforms, even though the average power level of these signals are the same. This error is due to the fact that not all power detectors strictly implement the definition for signal power, being the root mean square (RMS) of the signal. To cover for the systematic error in the output response of a detector, calibration can be used. After calibration a look-up table corrects for the error. Multiple look-up tables can be created for different modulation schemes. TYPES OF RF DETECTORS This section provides an overview of detectors based on their detection principle. Detectors that will be discussed are: * Peak Detectors * LOG Amp Detectors * RMS Detectors Peak Detectors A peak detector is one of the simplest type of detector, storing the highest value arising in a certain time window. However, a peak detector is typically used with a relatively long holding time when compared to the carrier frequency and a relatively short holding time with respect to the envelope frequency. In this way a peak detector is used as AM demodulator or envelope tracker (Figure 55). Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 17 LMH2120 SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 www.ti.com PEAK ENVELOPE CARRIER Figure 55. Peak Detection vs. Envelope Tracking A peak detector usually has a linear response. An example of this is a diode detector (Figure 56). The diode rectifies the RF input voltage; subsequently, the RC filter determines the averaging (holding) time. The selection of the holding time configures the diode detector for its particular application. For envelope tracking, a relatively small RC time constant is chosen such that the output voltage tracks the envelope nicely. In contrast, a configuration with a relatively large time constant measures the maximum (peak) voltage of a signal. Z0 D VREF C R VOUT Figure 56. Diode Detector Since peak detectors measure a peak voltage, their response is inherently dependent on the signal shape or modulation form as discussed in the previous section. Knowledge about the signal shape is required to determine an RMS value. For complex systems having various modulation schemes, the amount of calibration and look-up tables can become unmanageable. LOG Amp Detectors LOG Amp detectors are widely used RF power detectors for GSM and the early W-CDMA systems. The transfer function of a LOG amp detector has a linear-in-dB response, which means that the output in volts changes linearly with the RF power in dBm. This is convenient since most communication standards specify transmit power levels in dBm as well. LOG amp detectors implement the logarithmic function by a piecewise linear approximation. Consequently, the LOG amp detector does not implement an exact power measurement, which implies a dependency on the signal shape. In systems using various modulation schemes calibration and lookup tables might be required. RMS Detectors An RMS detector has a response that is insensitive to the signal shape and modulation form. This is because its operation is based on exact determination of the average power, i.e. it implements: VRMS = 2 1 v(t) dt T (3) RMS detectors are particularly suited for the newer communication standards like W-CDMA and LTE that exhibit large peak-to-average ratios and different modulation schemes (signal shapes). This is a key advantage compared to other types of detectors in applications that employ signals with high peak-to-average power variations or different modulation schemes. For example, the RMS detector response to a 0 dBm modulated WCDMA signal and a 0 dBm unmodulated carrier is essentially equal. This eliminates the need for long calibration procedures and large calibration tables in the application due to different applied modulation schemes. 18 Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 LMH2120 www.ti.com SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 LMH2120 RF POWER DETECTOR For optimal performance, the LMH2120 needs to be configured correctly in the application. The detector will be discussed by means of its block diagram (Figure 57). Details of the electrical interfacing are separately discussed for each pin below. A1 VDD LDO V/I V/I i1 RFIN B1 Internal Supply OUT iOUT A A2 VOUT i2 C2 EN V/I V/I GND C1, B2 Figure 57. Block Diagram For measuring the RMS (power) level of a signal, the time average of the squared signal needs to be measured as described in section ACCURATE POWER MEASUREMENT. This is implemented in the LMH2120 by means of a multiplier and a low-pass filter in a negative-feedback loop. A simplified block diagram of the LMH2120 is depicted in Figure 57. The core of the loop is a multiplier. The two inputs of the multiplier are fed by (i1, i2): i1 = iLF + iRF i1 = iLF - iRF (4) (5) in which iLF is a current depending on the DC output voltage of the RF detector and iRF is a current depending on the RF input signal. The output of the multiplier (iOUT) is the product of these two current and equals: 2 iOUT = 2 iLF - iRF I0 (6) in which I0 is a normalizing current. By a low-pass filter at the output of the multiplier the DC term of this current is isolated and integrated. The input of the amplifier A acts as the nulling point of the negative feedback loop, yielding: iLF dt = iRF dt 2 2 (7) which implies that the average power content of the current related to the output voltage of the LMH2120 is made equal to the average power content of the current related to the RF input signal. For a negative-feedback system, the transfer function is given by the inverse function of the feedback block. Therefore, to have a linear transfer for this RF detector, the feedback network implements a linear function as well resulting in an overall transfer function for the LMH2120 of: Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 19 LMH2120 SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 VOUT = k www.ti.com 2 vRF dt (8) in which k is the conversion gain. Note that as a result of the feedback loop a square root is also implemented, yielding the RMS function. Given this architecture for the RF detector, the high performance of the LMH2120 can be understood. In theory the accuracy of the linear transfer is set by: * The linear feedback network, which basically needs to process a DC signal only. * A high loop gain for the feedback loop, which is ensured by the amplifier gain A. The RMS functionality is inherent to the feedback loop and the use of a multiplier. Thus, a very accurate LINRMS RF power detector is obtained. To ensure a low dependency on the supply voltage, the internal detector circuitry is supplied via a low drop-out (LDO) regulator. This enables the usage of a wide range of supply voltage (2.7V to 5V) in combination with a low sensitivity of the output signal for the external supply voltage. RF Input RF systems typically use a characteristic impedance of 50; the LMH2120 is no exception to this. The RF input pin of the LMH2120 has an input impedance of 50. It enables an easy, direct connection to a directional coupler without the need for additional components (Figure 54). For an accurate power measurement the input power range of the LMH2120 needs to be aligned with the output power range of the power amplifier. This can be done by selecting a directional coupler with the appropriate coupling factor. Since the LMH2120 has a constant input impedance, a resistive divider can also be used instead of a directional coupler (Figure 58). RF ANTENNA PA R1 VDD A1 RFIN B1 A2 OUT LMH2120 EN ADC C2 B2, C1 GND Figure 58. Application with Resistive Divider Resistor R1 implements an attenuator, together with the detector input impedance, to match the output range of the PA with the input range of the LMH2120. The attenuation (AdB) realized by R1 and the effective input impedance (RIN) of the LMH2120 equals: R1 AdB = 20LOG 1 + RIN 1/4 (9) Solving this expression for R1 yields: 20 Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 LMH2120 www.ti.com SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 A dB 20 R1 = 10 - 11/4 RIN (10) Suppose the desired attenuation is 30 dB with a given LMH2120 input impedance of 50, the resistor R1 needs to be 1531. A practical value is 1.5 k. Although this is a cheaper solution than the application with directional coupler, it has a disadvantage. After calculating the resistor value it is possible that the realized attenuation is less than expected. This is because of the parasitic capacitance of resistor R1 which results in a lower actual realized attenuation. Whether the attenuation will be reduced depends on the frequency of the RF signal and the parasitic capacitance of resistor R1. Since the parasitic capacitance varies from resistor to resistor, exact determination of the realized attenuation can be difficult. A way to reduce the parasitic capacitance of resistor R1 is to realize it as a series connection of several separate resistors. Enable To save power, the LMH2120 can be brought into a low-power shutdown mode by means of the enable pin (EN). The device is active for EN = HIGH (VEN > 1.1V), and in the low-power shutdown mode for EN = LOW (VEN < 0.6V). In this state the output of the LMH2120 is switched to high-impedance. This high impedance prevents the discharge of the optional low-pass filter which is good for power efficiency. Using the shutdown function, care must be taken not to exceed the absolute maximum ratings. Since the device has an internal operating voltage of 2.5V, the voltage level on the enable should not be higher than 3V to prevent excess current flowing into the enable pin. Also enable voltage levels lower than 400 mV below GND should be prevented. In both cases the ESD devices start to conduct when the enable voltage range is exceeded and excess current will be drawn. A correct operation is not ensured then. The absolute maximum ratings are also exceeded when EN is switched to HIGH (from shutdown to active mode) while the supply voltage is switched off. This situation should be prevented at all times. A possible solution to protect the device is to add a resistor of 1 k in series with the enable input to limit the current. Output The output of the LMH2120 provides a DC voltage that is a measure for the applied RF power to the input pin. The output voltage has a linear-in-V response for an applied RF signal. RF power detectors can have some residual ripple on the output due to the modulation of the applied RF signal. The residual ripple on the LMH2120's output is small; therefore, additional filtering is usually not needed. This is because its internal averaging mechanism reduces the ripple significantly. For some modulation types having very high peak-to-average ratios or low-frequency components in the amplitude modulation, additional filtering might be useful. Filtering can be applied by an external low-pass filter. It should be realized that filtering reduces not only the ripple, but also increases the response time. In other words, it takes longer before the output reaches its final value. A trade-off should be made between allowed ripple and allowed response time. The filtering technique is depicted in Figure 59. The low-pass output filter is realized by resistor RS and capacitor CS. The -3 dB bandwidth of this filter can be calculated by: f-3 dB = 1 / (2RSCS) (11) VDD RFIN B1 A1 A2 OUT LMH2120 EN RS + CS C2 B2,C1 ADC GND Figure 59. Low-Pass Output Filter for Residual Ripple Reduction Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 21 LMH2120 SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 www.ti.com The output impedance of the LMH2120 is HIGH in shutdown. This is especially beneficial in pulsed mode systems. It ensures a fast settling time when the device returns from shutdown into active mode and reduces power consumption. In pulse mode systems, the device is active only during a fraction of the time. During the remaining time the device is in low-power shutdown. Pulsed mode system applications usually require that the output value is available at all times. This can be realized by a capacitor connected between the output and GND that "stores" the output voltage level. To apply this principle, discharging of the capacitor should be minimized in shutdown mode. The connected ADC input should thus have a high input impedance to prevent a possible discharge path through the ADC. When an additional filter is applied at the output, the capacitor of the RC-filter can be used to store the output value. An LMH2120 with a high-impedance shutdown mode saves power in pulse mode systems. This is because the capacitor CS doesn't need to be fully recharged each cycle. Supply The LMH2120 has an internal LDO to handle supply voltages between 2.7V to 5V. This enables a direct connection to the battery in cell phone applications. The high PSRR of the LMH2120 ensures that the performance is constant over its power supply range. SPECIFYING DETECTOR PERFORMANCE The performance of the LMH2120 can be expressed by a variety of parameters. This section discusses the key parameters. Dynamic Range The LMH2120 is designed to have a predictable and accurate response over a certain input power range. This is called the dynamic range (DR) of a detector. For determining the dynamic range a couple of different criteria can be used. The most commonly used ones are: * Linear conformance error, ELC * Variation over temperature error, EVOT * 1 dB step error, E1 dB * Variation due to Modulation, EMOD The specified dynamic range is the range in which the specified error metric is within a predefined window. An explanation of these errors is given in the following paragraphs. Linear Conformance error The LMH2120 implements a linear detection function. In order to describe how close the transfer is to an ideal linear function the linear conformance error is used. To calculate the linear conformance error the detector transfer function is modeled as a linear-in-V relationship between the input power and the output voltage. The ideal linear-in-V transfer is modeled by 2 parameters: * Slope, KSLOPE * Intercept, PINT and is described by: VOUT = KSLOPE (PIN - PINT) (12) where VOUT is the output voltage in dBV, KSLOPE is the slope of the function in dB/dB, PIN the input power level in dBm and PINT is the power level in dBm at which the function intersects VOUT = 0 dBV = 1V (See Figure 60). 22 Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 LMH2120 www.ti.com SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 10 PINT = RFIN at VOUT is 0 dBV (1V) PINT VOUT (V) 1 0.1 Detector response KSLOPE Ideal LIN function 0.01 -50 -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 60. Ideal Linear Response To determine the linear conformance error two steps are required: 1. Determine the best fitted line at 25C. 2. Determine the difference between the actual data and the best fitted line. The best fit can be determined by standard routines. A careful selection of the fit range is important. The fit range should be within the normal range of operation of the device. Outcome of the fit is KSLOPE and PINT. Subsequently, the difference between the actual data and the best fitted line is determined. The linear conformance is specified as an input referred error. The output referred error is therefore divided by the KSLOPE to obtain the input referred error. The linear conformance error is calculated by the following equation: VOUT (T) - KSLOPE 25C (PIN - PINT 25C ) ELC(T) = KSLOPE 25C (13) where VOUT (T) is the measured output voltage at a power level at PIN at a specific temperature. KSLOPE (dB/dB) and PINT 25C (dBm) are the parameters of the best fitted line of the 25C transfer. 25C Figure 61 shows that both the error with respect to the ideal LIN response as well as the error due to temperature variation are included in this error metric. This is because the measured data for all temperatures is compared to the fitted line at 25C. The measurement result of a typical LMH2120 in Figure 61 shows a dynamic range of 35 dB for ELC= 1dB. 3 ERROR (dB) 2 1 85C 25C 0 -40C -1 -2 -3 -50 -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 61. ELC vs. RF input Power at 1900 MHz Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 23 LMH2120 SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 www.ti.com Variation over Temperature Error In contrast to the linear conformance error, the variation over temperature error (EVOT) purely measures the error due to temperature variation. The measured output voltage at 25C is subtracted from the output voltage at another temperature. Subsequently, it is translated into an input referred error by dividing it by KSLOPE at 25C. The equation for variation over temperature is given by: EVOT = (VOUT_TEMP - VOUT 25C) / KSLOPE (14) The variation over temperature is shown in Figure 62, where a dynamic range of 40 dB is obtained for EVOT = 0.5 dB. 2.0 1.5 ERROR (dB) 1.0 85C 0.5 0.0 -0.5 -40C -1.0 -1.5 -2.0 -50 -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 62. EVOT vs. RF Input Power at 1900 MHz 1 dB Step Error This parameter is a measure for the error for an 1 dB power step. According to a 3GPP specification, the error should be less than 0.3 dB. This condition is often used to define a useful dynamic range of the detector. The 1 dB step error is calculated in 2 steps: 1. Determine the maximum sensitivity. 2. Calculate the 1 dB step error. First the maximum sensitivity (SMAX) is calculated per temperature. It is defined as the maximum difference between two output voltages for a 1 dB step within the power range: SMAX = VOUT P+1 - VOUT P (15) The 1dB error is than calculated by: E1 dB = (SACTUAL - SMAX) / SMAX (16) where SACTUAL (actual sensitivity) is the difference between two output voltages for a 1 dB step at a given power level. Figure 63 shows the typical 1 dB step error at 1900 MHz, where a dynamic range of 36 dB over temperature is obtained for E1dB = 0.3 dB. 24 Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 LMH2120 www.ti.com SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 1.5 1.2 0.9 ERROR (dB) 0.6 85C 0.3 0.0 -0.3 25C -0.6 -40C -0.9 -1.2 -1.5 -50 -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 63. 1 dB Step Error vs. RF Input Power at 1900 MHz 10 dB step error This error is defined in a different manner than the 1 dB step error. This parameter shows the input power error over temperature for a 10 dB power step. The 10 dB step at 25C is taken as a reference. VOUT (dBV) To determine the 10 dB step error first the output voltage levels (V1 and V2) for power levels "P" and "P+10dB" at the 25C are determined (Figure 64). Subsequently these 2 output voltages are used to determine the corresponding power levels at temperature T (PT and PT+X). The difference between those two power levels minus 10 results in the 10 dB step error. 25C response V2 Temp (T) response V1 RFIN (dBm) P PT P+10 dB PT+X Figure 64. Graphical Representation of 10 dB Step Error Calculations Figure 65 shows the typical 10 dB step error at 1900 MHz, where a dynamic range of 35 dB is obtained for E10dB = 1dB. Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 25 LMH2120 SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 www.ti.com 2.0 1.5 1.0 ERROR (dB) 85C 0.5 0.0 -0.5 -40C -1.0 -1.5 -2.0 -50 -40 -30 -20 -10 0 RF INPUT POWER (dBm) Figure 65. 10 dB Step Error vs. RF Input Power at 1900 MHz Variation due to Modulation RMS power detectors, such as the LMH2120 are inherently insensitive to different modulation schemes. This in contrast to traditional detectors like peak detectors and LOG AMP detectors, where modulation forms with high peak-to-average ratios (PAR) can cause significant output variation. This is because the measurement of these detectors is not an actual RMS measurement and is therefore waveform dependent. To be able to compare the various detector types on modulation sensitivity, the variation due to modulation parameter is used. To calculate the variation due to modulation (EMOD), the measurement result for an unmodulated RF carrier is subtracted from the measurement result for a modulated RF carrier. The calculations are similar to those for variation over temperature. The variation due to modulation can be calculated by: EMOD = (VOUT_MOD - VOUT_CW) / KSLOPE (17) where VOUT_MOD is the measured output voltage for an applied power level of a modulated signal, VOUT_CW is the output voltage as a result of an applied un-modulated signal having the same power level. Figure 66 shows the variation due to modulation for W-CDMA, where a EMOD of 0.16 dB is obtained for a dynamic range from -34 dBm to -2 dBm. 1.5 ERROR (dB) 1.0 W-CDMA, REL8 0.5 0.0 W-CDMA, REL6 -0.5 W-CDMA, REL7 -1.0 -1.5 -50 -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 66. Variation due to Modulation for W-CDMA at 1900 MHz 26 Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 LMH2120 www.ti.com SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 TEMPERATURE BEHAVIOR The specified temperature range of the LMH2120 is from -40C to 85C. The RF detector is, to a certain extent however, still functional outside these temperature limits. Figure 67, Figure 68, and Figure 69 show the detector behavior for temperatures from -50C up to 125C in steps of 25C. The LMH2120 is still very accurate within a dynamic range from -35 dBm to 5 dBm. On the upper and lower end the curves deviate in a gradual way, the lowest temperature on the bottom side and the highest temperature on top side. 10 125C In Steps of 25C 1 VOUT (V) -50C 0.1 125C 0.01 -50C 0.001 -50 -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 67. VOUT vs. RF Input Power at 1900 MHz 3 In Steps of 25C 2 ERROR (dB) -50C 125C 1 125C 0 -1 -50C -2 -3 -50 -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 68. Linear Conformance Error vs. RF Input Power at 1900 MHz Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 27 LMH2120 SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 www.ti.com 2.0 125C 100C 1.5 75C 1.0 ERROR (dB) 50C 0.5 0.0 -0.5 0C -1.0 -25C -1.5 -50C -2.0 -50 -40 -30 -20 -10 0 10 RF INPUT POWER (dBm) Figure 69. Temperature Variation vs. RF Input Power at 1900 MHz Layout Recommendations As with any other RF device, careful attention must be paid to the board layout. If the board layout isn't properly designed, performance might be less than can be expected for the application. The LMH2120 is designed to be used in RF applications, having a characteristic impedance of 50. To achieve this impedance, the input of the LMH2120 needs to be connected via a 50 transmission line. Transmission lines can be created on PCBs using microstrip or (grounded) coplanar waveguide (GCPW) configurations. In order to minimize injection of RF interference into the LMH2120 through the supply lines, the PCB traces for VDD and GND should be minimized for RF signals. This can be done by placing a decoupling capacitor between the VDD and GND. It should be placed as close as possible, to the VDD and GND pins of the LMH2120. 28 Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 LMH2120 www.ti.com SNWS021C - JULY 2010 - REVISED FEBRUARY 2013 REVISION HISTORY Changes from Revision B (February 2013) to Revision C * Page Changed layout of National Data Sheet to TI format .......................................................................................................... 28 Submit Documentation Feedback Copyright (c) 2010-2013, Texas Instruments Incorporated Product Folder Links: LMH2120 29 PACKAGE OPTION ADDENDUM www.ti.com 19-Oct-2017 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (C) Device Marking (4/5) LMH2120UM/NOPB NRND DSBGA YFZ 6 250 Green (RoHS & no Sb/Br) SNAGCU Level-1-260C-UNLIM -40 to 85 R LMH2120UMX/NOPB NRND DSBGA YFZ 6 3000 Green (RoHS & no Sb/Br) SNAGCU Level-1-260C-UNLIM -40 to 85 R (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based flame retardants must also meet the <=1000ppm threshold requirement. (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. 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Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 19-Oct-2017 Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 14-Mar-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) LMH2120UM/NOPB DSBGA YFZ 6 250 178.0 8.4 LMH2120UMX/NOPB DSBGA YFZ 6 3000 178.0 8.4 Pack Materials-Page 1 B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 0.89 1.3 0.56 4.0 8.0 Q1 0.89 1.3 0.56 4.0 8.0 Q1 PACKAGE MATERIALS INFORMATION www.ti.com 14-Mar-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LMH2120UM/NOPB DSBGA YFZ LMH2120UMX/NOPB DSBGA YFZ 6 250 210.0 185.0 35.0 6 3000 210.0 185.0 35.0 Pack Materials-Page 2 MECHANICAL DATA YFZ0006xxx D 0.425 0.045 E UMD06XXX (Rev B) D: Max = 1.246 mm, Min =1.186 mm E: Max = 0.846 mm, Min =0.786 mm 4215131/A NOTES: A. All linear dimensions are in millimeters. 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