APPLICATION INFORMATION 2.4 GHz power amplifier with the BFG425W and the BFG21W Philips Semiconductors Application information 2.4 GHz power amplifier with the BFG425W and the BFG21W ABSTRACT * Description of the product The BFG425W is a double polysilicon wideband transistor and the BFG21W is a double polysilicon bipolar power transistor. * Application area Low voltage high frequency wireless applications. * Presented application A 2-stage power amplifier for a 2.4 GHz WLAN with bias circuitry for load power adjustment an on/off switching. * Main results Operating at a single supply voltage of 3.0 V and an input power of 0 dBm, the amplifier delivers an output power of 22 dBm with a power added efficiency of 44%. PHILIPS ELECTRONICS N.V. 1999 All rights are reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. No liability will be accepted by the publisher for any consequence of its use. Publication thereof does not convey nor imply any license under patent- or other industrial or intellectual property rights. 2000 Feb 02 2 Philips Semiconductors Application information 2.4 GHz power amplifier with the BFG425W and the BFG21W INTRODUCTION The Philips transistors BFG425W and BFG21W used in this amplifier, are manufactured according to the double polysilicon process and are characterised by a transition frequency greater than 20 GHz at low supply voltages. The amplifier is well suited for the new generation low voltage high frequency applications. This application note describes a two-stage power amplifier, designed to be used in 2.4 GHz WLAN systems. With only two transistors a small sized power amplifier line-up is realized, offering 22 dBm of output power with 44% power added efficiency at 0 dBm input power and a single 3 V supply voltage. Biasing is done by a circuit around an NPN transistor pair, which also performs load power adjustment and the possibility for on/off switching. Thanks to the low component count and simple matching networks, the entire power amplifier (including bias part) only measures 10 x 20 mm. PERFORMANCE OVERVIEW The following initial conditions apply for the power amplifier measurements (unless otherwise stated): * Supply voltage 3.0 V * Control voltage 3.0 V * Frequency 2.45 GHz * Source and load impedance 50 * Input power 0 dBm. Table 1 Characteristics of the 2.4 GHz WLAN power amplifier SYMBOL PARAMETER CONDITION VALUE UNIT Po output power 22.4 dBm GP power gain 22.4 dB Isupply supply current 136 mA PA power added efficiency 44 % VSWRIN input voltage standing wave ratio 2 s21/s122 isolation Spurious relative to input power; Vctrl < 0.6 V 40 dB VSWR = 6; all phases -55 dBc off-state; Vctrl < 0.6 V <10 A IL leakage current d2H 2nd harmonic distortion -42 dBc d3H 3rd harmonic distortion -35 dBc For other applications with this amplifier circuit, the following conditions apply * Supply voltage from 3.0 to 5.0 V; for CW mode of operation, the supply voltage must be smaller than 4.0 V, for pulsed mode greater than 4.0 V. * Control voltage greater than 2.2 V for the ON-state and smaller than 0.6 V for the OFF-state. * Frequency range from 2.4 to 2.5 GHz. 2000 Feb 02 3 Philips Semiconductors Application information 2.4 GHz power amplifier with the BFG425W and the BFG21W CIRCUIT DESCRIPTION Figure 1 shows the circuit diagram of the WLAN power amplifier including both RF transistors, matching circuits and biasing circuit. The RF chain of the power amplifier consists of two transistor stages: a BFG425W (TR1) wideband transistor and a BFG21W (TR2) power transistor, both operating in class AB. In accordance with this mode and the required output power of each stage, the measured source and load impedances of both transistors are given in Table 2. The SOT343R packaged R transistors have two emitters leads, which have to be carefully grounded to ensure stable operation and performance according to specification. The layout of this power amplifier offers an emitter-to-ground inductance of typically 130 pH. The biasing part of the power amplifier is build around an NPN transistor pair, TR3a and TR3b. The circuit delivers a temperature compensated bias voltage for both RF stages. The circuit offers maximum gain when the control voltage is greater than 2.2 V. The bias voltage for the first stage is approximately 0.90 V and for the second stage approximately 0.65 V. Vsupply Vctrl handbook, full pagewidth R7 R4 C13 TR3a R3 C7 C12 C9 R5 R2 C8 TR3b C6 S8 R6 S2 R1 S4 C4 input C11 output S6 TR2 S1 C1 S7 S5 S3 TR1 C3 C5 C10 C2 MGS878 Fig.1 Circuit diagram. Table 2 Source and load impedances of the applied RF transistors TRANSISTOR CONDITIONS SOURCE IMPEDANCE (ZS) LOAD IMPEDANCE (ZL) BFG425W VCE = 3.0 V; VBE = 0.9 V; Po = 15 dBm; GP = 14 dB; f = 2.45 GHz 20 + 27 j 45 + 37 j BFG21W VCE = 3.0 V; VBE = 0.65 V; Po = 22.5 dBm; GP = 7.5 dB; f = 2.45 GHz 8 - 11 j 11 - 11 j 2000 Feb 02 4 Philips Semiconductors Application information 2.4 GHz power amplifier with the BFG425W and the BFG21W COMPONENT LIST Table 3 Component list for the 2.4 GHz WLAN power amplifier circuit COMPONENT VALUE UNIT SIZE - MANUFACTURER TR1 BFG425W SOT343R Philips TR2 BFG21W SOT343RPhilips TR3 PUMX1 SOT363 Philips R1 560 0603 Philips R2 10 0603 Philips R3 10 0603 Philips R4 220 0603 Philips R5 82 0603 Philips R6 330 0603 Philips R7 1 k 0603 Philips C1 2.2 pF 0603 Philips C2 1.2 pF 0603 Philips C3 0.47 pF 0603 Philips C4 2.2 pF 0603 Philips C5 1.8 pF 0603 Philips C6 10 pF 0603 Philips C7 10 nF 0603 Philips C8 10 pF 0603 Philips C9 1 nF 0603 Philips C10 2.2 pF 0603 Philips C11 6.8 pF 0603 Philips C12 10 pF 0603 Philips C13 1 nF 0603 Philips S1 L = 6.5; W = 0.45 mm S2 L = 3.0; W = 0.15 mm S3 L = 7.5; W = 0.15 mm S4 L = 2.0; W = 1.15 mm S5 L = 7.5; W = 0.15 mm S6 L = 2.0; W = 1.15 mm S7 L = 5.0; W = 0.45 mm S8 L = 6.5; W = 0.15 mm PCB FR4 2000 Feb 02 r = 4.6; d = 0.71 mm 5 Philips Semiconductors Application information 2.4 GHz power amplifier with the BFG425W and the BFG21W BOARD LAYOUT Figure 2 shows the layout of the power amplifier printed circuit board, which has the following properties: * FR4 bilayer (backside ground) * d = 0.71 mm * t = 35 m (Cu cladding, not coated) * r = 4.6 * tan = 0.02. The position of components C2, C3, C5 and C10 is critical. C5 S2 TR1 C3 handbook, full pagewidth S4 S6 C4 TR2 S1 C8 C11 R6 TR3 C1 C10 C9 C12 R5 S8 R2 R1 C6 R4 R3 S5 C13 S3 C7 C2 S7 R7 input output Vctrl GND Vsupply MGS879 Fig.2 Layout of the WLAN power amplifier printed circuit board. 2000 Feb 02 6 Philips Semiconductors Application information 2.4 GHz power amplifier with the BFG425W and the BFG21W SPICE PARAMETERS The spice parameters of the two applied transistors are given in Table 4 and Table 5. Table 4 Spice parameters of the BFG425W + MJS = 0.2391 .SUBCKT BFG425W 1 2 3 + XCJC = 0.5 L1 2 5 1.1E-09 + TR = 0.0 L2 1 4 1.1E-09 + TF = 4.122E-12 L3 3 6 0.25E-09 + XTF = 68.2 Ccb 4 5 2.0E-15 + VTF = 2.004 Cbe 5 6 80.0E-15 + ITF = 1.525 Cce 4 6 80.0E-15 + PTF = 0 Cbpb 5 7 1.45E-13 + FC = 0.5501 Cbpc 4 8 1.45E-13 + EG = 1.11 Rsb1 6 7 25 + XTI = 3 Rsb2 6 8 19 + XTB = 1.5 Q1 4 5 6 6 NPN .ENDS .MODEL NPN NPN + IS = 4.717E-17 + BF = 145 + NF = 0.9934 + VAF = 31.12 + IKF = 0.304 + ISE = 3.002E-13 + NE = 3 + BR = 11.37 + NR = 0.985 + VAR = 1.874 + IKR = 0.121 + ISC = 4.848E-16 + NC = 1.546 + RB = 14.41 + IRB = 0 + RBM = 6.175 + RE = 0.1779 + RC = 1.780 + CJE = 3.109E-13 + VJE = 0.9 + MJE = 0.3456 + CJC = 1.377E-13 + VJC = 0.5569 + MJC = 0.2079 + CJS = 6.675E-13 + VJS = 0.4183 2000 Feb 02 7 Philips Semiconductors Application information 2.4 GHz power amplifier with the BFG425W and the BFG21W Table 5 Spice parameters of the BFG21W + ISC = 2.503E-15 .SUBCKT BFG21W 10 11 12 + NC = 1.209 Lbbond 2 5 7.209E-10 + RB = 1.492 Lblead 5 8 2.251E-10 + IRB = 0 Lbfoot 8 11 1.1E-10 + RBM = 0.3202 Cbfoot 8 12 1.17E-13 + RE = 0.3429 Lebond 3 6 5.15E-11 + RC = 0.8 Lelead 6 9 6.914E-11 + CJE = 3.026E-12 Lefoot 9 12 1.739E-10 + VJE = 0.9 Cefoot 9 12 1.95E-13 + MJE = 0.2861 Lcbond 1 4 5.711E-10 + CJC = 1.041E-12 Lclead 4 7 2.251E-10 + VJC = 0.6964 Lcfoot 7 10 1.1E-10 + MJC = 0.308 Ccfoot 7 12 1.17E-13 + CJS = 1.844E-12 Cbc 5 4 2E-15 + VJS = 0.4237 Cbe 5 6 8E-14 + MJS = 0.2606 Cce 4 6 8E-14 + XCJC = 0.5 Cbpb 2 14 3.3E-13 + TR = 1.5E-10 Cbpc 1 13 3.47E-13 + TF = 5.05E-12 Cmet 1 3 1.7E-12 + XTF = 74 Rsub1 14 15 249.2 + VTF = 0.8 Rsub2 13 15 464.4 + ITF = 6.5 Rmut 3 15 100 + PTF = 0 Dio 16 1 + FC = 0.875 + D1 + EG = 1.11 Rs 15 16 3.5 + XTI = 4.3 .MODEL D1 D + XTB = 0.5 + IS = 4.99E-13 .ENDS + N = 1.189 Q1 1 2 3 3 NPN + AREA = 1 .MODEL NPN NPN + IS = 3.835E-16 + BF = 92 + NF = 1 + VAF = 35 + IKF = 2.8 + ISE = 9.005E-13 + NE = 2.262 + BR = 8.9 + NR = 1.009 + VAR = 2.25 + IKR = 0.6507 2000 Feb 02 8 Philips Semiconductors Application information 2.4 GHz power amplifier with the BFG425W and the BFG21W MEASUREMENTS The result of the measurements is given in the Figs 3 to 8. The following initial conditions apply for all measurements (unless otherwise specified): * Vsupply = 3.0 V * Vctrl = 3.0 V * f = 2.45 GHz * Pi = 0 dBm. MGS880 MGS881 50 30 handbook, halfpage PA handbook, halfpage GP (dB) (%) 26 40 22 30 18 20 14 10 0 10 5 15 Po (dB) 5 25 Fig.4 Fig.3 Power gain as a function of the output power. 2000 Feb 02 9 15 Po (dB) 25 Power added efficiency as a function of the output power. Philips Semiconductors Application information 2.4 GHz power amplifier with the BFG425W and the BFG21W MGS882 MGS883 40 GP 30 handbook, halfpage handbook, halfpage GP (dB) (dB) 20 28 0 26 -20 24 -40 -60 Fig.5 22 0.6 0 1.2 1.8 20 2.4 3.0 Vctrl (V) 3 Power gain as a function of the control voltage. Fig.6 4 Vsupply (V) 5 Power gain as a function of the supply voltage. MGS885 MGS884 30 GP 40 handbook, halfpage handbook, halfpage GP (dB) (dB) 20 28 0 26 -20 24 -40 22 -60 0.1 Fig.7 1.1 2.1 3.1 4.1 20 2.40 5.1 f (GHz) Power gain as a function of the frequency, wideband measurement. 2000 Feb 02 Fig.8 10 2.42 2.44 2.46 2.48 2.50 f (GHz) Power gain as a function of the frequency, narrow band measurement. Philips Semiconductors Application information 2.4 GHz power amplifier with the BFG425W and the BFG21W NOTES 2000 Feb 02 11 Philips Semiconductors - a worldwide company Argentina: see South America Australia: 3 Figtree Drive, HOMEBUSH, NSW 2140, Tel. +61 2 9704 8141, Fax. +61 2 9704 8139 Austria: Computerstr. 6, A-1101 WIEN, P.O. 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Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. No liability will be accepted by the publisher for any consequence of its use. Publication thereof does not convey nor imply any license under patent- or other industrial or intellectual property rights. Printed in The Netherlands 603508/01/pp12 Date of release: 2000 Feb 02