LT5578
1
5578f
TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
0.4GHz to 2.7GHz
High Linearity
Upconverting Mixer
n GSM 900PCS/1800PCS and W-CDMA Infrastructure
n LTE and WiMAX Basestations
n Wireless Repeaters
n Public Safety Radios
Frequency Upconversion in LTE Transmitter
Gain, NF and OIP3 vs
RF Output Frequency
n High Output IP3: 27dBm at 0.9GHz
24.3dBm at 1.95GHz
n Low Noise Floor: –158dBm/Hz (POUT = –5dBm)
n High Conversion Gain: 1.4dB at 0.9GHz
n Noise Figure: 8.6dB
n Low LO-RF Leakage: –43dBm
n Single-Ended RF and LO Ports
n Low LO Drive Level: –1dBm
n Single 3.3V Supply
n 5mm × 5mm QFN24 Package
(Pin Compatible with LT5579)
The LT
®
5578 mixer is a high performance upconverting
mixer optimized for frequencies in the 0.4GHz to 2.7GHz
range. The single-ended LO input and RF output ports
simplify board layout and reduce system cost. The mixer
needs only –1dBm of LO power and the balanced design
results in low LO signal leakage to the RF output. At
1.95GHz operation, the LT5578 provides conversion gain
of –0.7dB, high OIP3 of 24.3dBm and a low noise fl oor of
–158dBm/Hz at a –5dBm RF output signal level.
The LT5578 offers a high performance alternative to pas-
sive mixers. Unlike passive mixers, which have conversion
loss and require high LO drive levels, the LT5578 delivers
conversion gain at signifi cantly lower LO input levels and
is less sensitive to LO power level variations. The lower
LO drive level requirements, combined with the excellent
LO leakage performance, translate into lower LO signal
contamination of the output signal.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
BIAS
LT5578
RF
GND
LO
VCC
VCC
3.3V
5579 TA01a
10μF
IF+
IF–
100nH
13.7Ω
13.7Ω
39pF
220pF
TC4-1W+
4:1
220pF
6.8pF2.7pF
100μF 1nF
2pF
RF
700MHz
TO 950MHz
LO INPUT
–1dBm
IF
140MHz 22nH
2.7pF
13nH
100nH
RF OUTPUT FREQUENCY (MHz)
650
GAIN (dB), NF (dB), OIP3 (dBm)
20
25
30
OIP3
800 900
5578 TA01b
15
10
700 750 850 950 1000
5
0
SSB NF
GAIN
TA = 25°C
fIF = 140MHz
fLO = fRF – fIF
LT5578
2
5578f
PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS
Supply Voltage ............................................................4V
LO Input Power ....................................................10dBm
LO Input DC Current ..............................................30mA
RF Output DC Current ............................................45mA
IF Input Power (Differential) .................................18dBm
IF+, IF– DC Currents ...............................................45mA
TJMAX .................................................................... 150°C
Operating Temperature Range.................. –40°C to 85°C
Storage Temperature Range ................... –65°C to 150°C
(Note 1)
24 23 22 21 20 19
7 8 9
TOP VIEW
25
UH PACKAGE
24-LEAD (5mm s 5mm) PLASTIC QFN
10 11 12
6
5
4
3
2
1
13
14
15
16
17
18
GND
GND
IF+
IF–
GND
GND
GND
GND
GND
RF
GND
GND
GND
GND
LO
GND
GND
GND
GND
VCC
VCC
VCC
VCC
GND
TJMAX = 150°C, θJA = 34°C/W
EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LT5578IUH#PBF LT5578IUH#TRPBF 5578 24-Lead (5mm × 5mm) Plastic QFN –40°C to 85°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based fi nish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifi cations, go to: http://www.linear.com/tapeandreel/
DC ELECTRICAL CHARACTERISTICS
VCC = 3.3V, TA = 25°C (Note 3), unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Power Supply Requirements (VCC)
Supply Voltage 3.1 3.3 3.5 VDC
Supply Current VCC = 3.3V, PLO = –1dBm
VCC = 3.5V, PLO = –1dBm
152
159
170 mA
mA
Input Common Mode Voltage (VCM) Internally Regulated 565 mV
AC ELECTRICAL CHARACTERISTICS
(Notes 2, 3)
PARAMETER CONDITIONS MIN TYP MAX UNITS
IF Input Frequency Range (Note 4) Requires Matching LF to 600 MHz
LO Input Frequency Range (Note 4) Requires Matching Below 1.5GHz 400 to 3000 MHz
RF Output Frequency Range (Note 4) Requires Matching 400 to 2700 MHz
LT5578
3
5578f
AC ELECTRICAL CHARACTERISTICS
V
CC = 3.3V, TA = 25°C, Test circuits are shown in Figure 1. (Notes 2, 3)
PARAMETER CONDITIONS MIN TYP MAX UNITS
IF Input Return Loss ZO = 50Ω, External Match 15 dB
LO Input Return Loss ZO = 50Ω, External Match >9 dB
RF Output Return Loss ZO = 50Ω, External Match >10 dB
LO Input Power –5 to 2 dBm
VCC = 3.3V, TA = 25°C, PIF = –5dBm (–5dBm/tone for 2-tone tests, Δf = 1MHz), PLO = –1dBm, unless otherwise noted.
Low side LO for 900MHz. High side LO for 740MHz and 1950MHz. (Notes 2, 3, 4)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Conversion Gain fRF = 740MHz, fIF = 140MHz
fRF = 900MHz, fIF = 140MHz
fRF = 1950MHz, fIF = 240MHz
0.8
1.4
–0.7
dB
dB
dB
Conversion Gain vs Temperature
(TA = –40°C to 85°C)
fRF = 740MHz, fIF = 140MHz
fRF = 900MHz, fIF = 140MHz
fRF = 1950MHz, fIF = 240MHz
–0.020
–0.018
–0.021
dB/°C
dB/°C
dB/°C
Output 3rd Order Intercept fRF = 740MHz, fIF = 140MHz
fRF = 900MHz, fIF = 140MHz
fRF = 1950MHz, fIF = 240MHz
26.5
27.0
24.3
dBm
dBm
dBm
Output 2nd Order Intercept (LO ±2IF) fRF = 740MHz, fIF = 140MHz
fRF = 900MHz, fIF = 140MHz
fRF = 1950MHz, fIF = 240MHz
62
52
58
dBm
dBm
dBm
Single Sideband Noise Figure fRF = 740MHz, fIF = 140MHz
fRF = 900MHz, fIF = 140MHz
fRF = 1950MHz, fIF = 240MHz
8.6
8.6
10.5
dB
dB
dB
Output Noise: POUT = –5dBm fRF = 740MHz, fIF = 140MHz
fRF = 900MHz, fIF = 140MHz
fRF = 1950MHz, fIF = 240MHz
–161
–160.5
–158
dBm/Hz
dBm/Hz
dBm/Hz
Output Noise: POUT = 0dBm fRF = 740MHz, fIF = 140MHz
fRF = 900MHz, fIF = 140MHz
fRF = 1950MHz, fIF = 240MHz
–158
–157.5
–154
dBm/Hz
dBm/Hz
dBm/Hz
Output Noise: POUT = 5dBm fRF = 740MHz, fIF = 140MHz
fRF = 900MHz, fIF = 140MHz
fRF = 1950MHz, fIF = 240MHz
–154
–153
–149.5
dBm/Hz
dBm/Hz
dBm/Hz
Output 1dB Compression fRF = 740MHz, fIF = 140MHz
fRF = 900MHz, fIF = 140MHz
fRF = 1950MHz, fIF = 240MHz
11.6
12
10
dBm
dBm
dBm
IF to LO Isolation fRF = 740MHz, fIF = 140MHz
fRF = 900MHz, fIF = 140MHz
fRF = 1950MHz, fIF = 240MHz
80
75
60
dB
dB
dB
LO to IF Leakage fRF = 740MHz, fIF = 140MHz
fRF = 900MHz, fIF = 140MHz
fRF = 1950MHz, fIF = 240MHz
–31
–40
–22
dBm
dBm
dBm
LO to RF Leakage fRF = 740MHz, fIF = 140MHz
fRF = 900MHz, fIF = 140MHz
fRF = 1950MHz, fIF = 240MHz
–43
–43
–46
dBm
dBm
dBm
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: Each set of frequency conditions requires appropriate matching
(see Figure 1).
Note 3: The LT5578 is guaranteed functional over the operating
temperature range from –40°C to 85°C.
Note 4: SSB noise fi gure measurements performed with a small-signal
noise source and bandpass fi lter on LO signal generator. No other IF signal
applied.
LT5578
4
5578f
TYPICAL AC PERFORMANCE CHARACTERISTICS
TYPICAL DC PERFORMANCE CHARACTERISTICS
Supply Current vs Supply Voltage
Gain Distribution at 900MHz OIP3 Distribution at 900MHz
SSB Noise Figure Distribution at
900MHz
(Test Circuit Shown in Figure 1)
900MHz Application:
VCC = 3.3V, TA = 25°C, fIF = 140MHz, PIF = –5dBm (–5dBm/tone for 2-tone tests, Δf = 1MHz), low side LO, PLO = –1dBm,
output measured at 900MHz, unless otherwise noted. (Test circuit shown in Figure 1)
SUPPLY VOLTAGE (V)
3.0
120
SUPPLY CURRENT (mA)
130
140
150
160
180
3.1 3.2 3.3 3.4
5578 G01
3.5 3.6
170
85°C
25°C
–40°C
GAIN (dB)
–0.5
DISTRIBUTION (%)
25
35
45
1.0 2.0 3.5
5578 G02
15
5
20
30
40
10
0
0 0.5 1.5 2.5 3.0
TA = 90°C
TA = 25°C
TA = –45°C
OIP3 (dBm)
23
0
DISTRIBUTION (%)
5
10
15
20
25
24 25 26 27
5578 G03
28 29
TA = 90°C
TA = 25°C
TA = –45°C
NOISE FIGURE (dB)
6
0
DISTRIBUTION (%)
10
20
30
40
50
60
78910
5578 G04
11
TA = 90°C
TA = 25°C
TA = –45°C
LT5578
5
5578f
Conversion Gain and OIP3
vs RF Output Frequency
SSB Noise Figure
vs RF Output Frequency
LO-RF Leakage
vs RF Output Frequency
Conversion Gain and OIP3
vs LO Input Power
SSB Noise Figure
vs LO Input Power
Conversion Gain and OIP3
vs Supply Voltage
IM3 Level
vs RF Output Power (2-Tone)
IM2 Level
vs RF Output Power (1-Tone)
SSB Noise Figure
vs Supply Voltage
TYPICAL AC PERFORMANCE CHARACTERISTICS
VCC = 3.3V, TA = 25°C, fIF = 140MHz, PIF = –5dBm (–5dBm/tone for 2-tone tests, Δf = 1MHz), high side LO, PLO = –1dBm,
output measured at 740MHz, unless otherwise noted. (Test circuit shown in Figure 1)
740MHz Application:
RF FREQUENCY (MHz)
660 680
–4
GAIN (dB)
OIP3 (dBm)
4
16
700 740 760
5578 G05
0
12
8
10
18
30
OIP3
GAIN
14
26
22
720 780 800
85°C
25°C
–40°C
RF FREQUENCY (MHz)
660
NOISE FIGURE (dB)
18
720
5578 G06
12
8
680 700 740
6
4
2
16
14
10
760 780 800
85°C
25°C
–40°C
RF FREQUENCY (MHz)
660 680
–60
–50
LO LEAKAGE (dBm)
–30
0
700 740 760
5578 G07
–40
–10
–20
720 780 800
85°C
25°C
–40°C
LO INPUT POWER (dBm)
–17
GAIN (dB)
OIP3 (dBm)
8
12
16
–1
5578 G08
4GAIN
OIP3
0
–4
18
22
26
30
14
10
–13 –9 –5 3
85°C
25°C
–40°C
LO INPUT POWER (dBm)
–17
NOISE FIGURE (dB)
12
14
16
3
5578 G09
10
8
4
2
–13 –9 –5 –1
6
18
85°C
25°C
–40°C
SUPPLY VOLTAGE (V)
3.0
–4
GAIN (dB)
OIP3 (dBm)
0
4
8
12
16
OIP3
GAIN
10
14
18
22
26
30
3.1 3.2 3.3 3.4
5578 G10
3.5
85°C
25°C
–40°C
RF OUTPUT POWER (dBm/TONE)
–12
–100
IM3 LEVEL (dBc)
–80
–40
–20
0
–8 –4 –2 6
5578 G11
–60
–10 –6 024
85°C
25°C
–40°C
RF OUTPUT POWER (dBm)
–12
–100
IM2 LEVEL (dBc)
–80
–40
–20
0
–8 –4 –2 6
5578 G12
–60
–10 –6 024
85°C
25°C
–40°C
SUPPLY VOLTAGE (V)
3.0
NOISE FIGURE (dB)
10
12
14
3.3
5578 G13
8
6
4
2
3.1 3.2 3.4
16
18
3.5
85°C
25°C
–40°C
LT5578
6
5578f
Conversion Gain and OIP3
vs RF Output Frequency
SSB Noise Figure
vs RF Output Frequency
LO-RF Leakage
vs RF Output Frequency
Conversion Gain and OIP3
vs LO Input Power
SSB Noise Figure
vs LO Input Power
Conversion Gain and OIP3
vs Supply Voltage
IM3 Level
vs RF Output Power (2-Tone)
IM2 Level
vs RF Output Power (1-Tone)
SSB Noise Figure
vs Supply Voltage
TYPICAL AC PERFORMANCE CHARACTERISTICS
VCC = 3.3V, TA = 25°C, fIF = 140MHz, PIF = –5dBm (–5dBm/tone for 2-tone tests, Δf = 1MHz), low side LO, PLO = –1dBm,
output measured at 900MHz, unless otherwise noted. (Test circuit shown in Figure 1)
900MHz Application:
RF FREQUENCY (MHz)
830
–4
GAIN (dB)
OIP3 (dBm)
0
4
8
12
16
OIP3
10
14
18
22
26
30
850 870 890 910
5578 G14
930 950 970
85°C
25°C
–40°C
GAIN
RF FREQUENCY (MHz)
830
NOISE FIGURE (dB)
8
10
12
890 930 950
5578 G15
6
4
2850 870 910
14
16
18
970
85°C
25°C
–40°C
RF FREQUENCY (MHz)
830 850
–60
–50
LO LEAKAGE (dBm)
–30
0
870 910 930
5578 G16
–40
–10
–20
890 950 970
85°C
25°C
–40°C
LO INPUT POWER (dBm)
–17
GAIN (dB)
OIP3 (dBm)
8
12
16
–1
5578 G17
4
OIP3
0
–4
22
26
30
18
14
10
–13 –9 –5 3
85°C
25°C
–40°C
GAIN
LO INPUT POWER (dBm)
–17
NOISE FIGURE (dB)
10
12
14
3–1
5578 G18
8
6
2–13 –9 –5
4
18
16
85°C
25°C
–40°C
SUPPLY VOLTAGE (V)
3.0
–4
GAIN (dB)
OIP3 (dBm)
0
4
8
16
12
10
14
18
22
30
26
3.1 3.2 3.3
OIP3
3.4
5578 G19
3.5
85°C
25°C
–40°C
GAIN
RF OUTPUT POWER (dBm/TONE)
–12
–100
IM3 LEVEL (dBc)
–80
–40
–20
0
–8 –4 –2 6
5578 G20
–60
–10 –6 024
85°C
25°C
–40°C
RF OUTPUT POWER (dBm)
–12
–100
–80
IM2 LEVEL (dBc)
–40
–20
0
–8 –4 –2 6
5578 G21
–60
–10 –6 024
85°C
25°C
–40°C
SUPPLY VOLTAGE (V)
3.0
NOISE FIGURE (dB)
8
10
12
3.3
5578 G22
6
4
23.1 3.2 3.4
14
16
18
3.5
85°C
25°C
–40°C
LT5578
7
5578f
Conversion Gain and OIP3
vs RF Output Frequency
SSB Noise Figure
vs RF Output Frequency
LO-RF Leakage
vs RF Output Frequency
Conversion Gain and OIP3
vs LO Input Power
SSB Noise Figure
vs LO Input Power
Conversion Gain and OIP3
vs Supply Voltage
IM3 Level
vs RF Output Power (2-Tone)
IM2 Level
vs RF Output Power (1-Tone)
SSB Noise Figure
vs Supply Voltage
TYPICAL PERFORMANCE CHARACTERISTICS
VCC = 3.3V, TA = 25°C, fIF = 240MHz, PIF = –5dBm (–5dBm/tone for 2-tone tests, Δf = 1MHz), high side LO, PLO = –1dBm,
output measured at 1950MHz, unless otherwise noted. (Test circuit shown in Figure 1)
1950MHz Application:
RF FREQUENCY (MHz)
1600
GAIN (dB)
OIP3 (dBm)
4
8
2200
5578 G23
0
–4 1700 1800 1900
GAIN
OIP3
2000 2100
16
12
16
20
12
8
28
24
85°C
25°C
–40°C
RF FREQUENCY (MHz)
1600
NOISE FIGURE (dB)
10
12
14
2200
5578 G24
8
6
21700 1800 1900 21002000
4
18
16
85°C
25°C
–40°C
RF FREQUENCY (MHz)
1600 1700
–60
–50
LO LEAKAGE (dBm)
–30
0
1800 2000 2100
5578 G25
–40
–10
–20
1900 2200 2300
85°C
25°C
–40°C
LO INPUT POWER (dBm)
–17
GAIN (dB)
OIP3 (dBm)
8
12
16
–1
5578 G26
4
OIP3
0
–4
20
24
28
16
12
8
–13 –9 –5 3
85°C
25°C
–40°C
GAIN
LO INPUT POWER (dBm)
–17
NOISE FIGURE (dB)
10
12
14
3–1
5578 G27
8
6
2–13 –9 –5
4
18
16
85°C
25°C
–40°C
SUPPLY VOLTAGE (V)
3.0
–4
GAIN (dB)
OIP3 (dBm)
0
4
8
16
12
8
12
16
20
28
24
3.1 3.2 3.3 3.4
GAIN
OIP3
5578 G28
3.5
85°C
25°C
–40°C
RF OUTPUT POWER (dBm/TONE)
–14
IM3 LEVEL (dBc)
–40
–20
0
–8 –4 42
5578 G29
–60
–80
–100
–12 –10 –6 –2 0
85°C
25°C
–40°C
RF OUTPUT POWER (dBm)
–14
IM2 LEVEL (dBc)
–40
–20
0
–8 –4 42
5578 G30
–60
–80
–100
–12 –10 –6 –2 0
85°C
25°C
–40°C
SUPPLY VOLTAGE (V)
3.0
NOISE FIGURE (dB)
10
12
14
3.53.4
5578 G31
8
6
23.1 3.2 3.3
4
18
16
85°C
25°C
–40°C
LT5578
8
5578f
PIN FUNCTIONS
GND (Pins 1, 2, 5-7, 12-14, 16-21, 23, 24): Ground
Connections. These pins are internally connected to the
exposed pad and should be soldered to a low impedance
RF ground on the printed circuit board.
IF+, IF– (Pins 3, 4): Differential IF Input. The common
mode voltage on these pins is set internally to 565mV. The
DC current from each pin is determined by the value of
an external resistor to ground. The maximum DC current
through each pin is 45mA.
VCC (Pins 8-11): Power Supply Pins for the IC. These
pins are connected together internally. Typical current
consumption is 152mA. These pins should be connected
together on the circuit board with external bypass capaci-
tors of 1000pF, 100pF and 10pF located as close to the
pins as possible.
RF (Pin 15): Single-Ended RF Output. This pin is con-
nected to an internal transformer winding. The opposite
end of the winding is grounded internally. An impedance
transformation may be required to match the output and a
DC decoupling capacitor is required if the following stage
has a DC bias voltage present.
LO (Pin 22): Single-Ended Local Oscillator Input. An internal
series capacitor acts as a DC block to this pin.
Exposed Pad (Pin 25): PGND. Electrical and thermal
ground connection for the entire IC. This pad must be
soldered to a low impedance RF ground on the printed
circuit board. This ground must also provide a path for
thermal dissipation.
BLOCK DIAGRAM
LO BUFFER
LO
GND PINS ARE NOT SHOWN
DOUBLE
BALANCED
MIXER
RF
VCC
22
11
15
EXPOSED
PAD
25
VCC
VCC
VCC
5578 BD
BIAS
IF+IF–
VCM
CTRL
VCC2
VCC2
10
9
8
3 4
LT5578
9
5578f
TEST CIRCUIT
Figure 1. Test Circuit Schematic and Component Values
REF DES
fRF = 740MHz
fIF = 140MHz
fLO = 880MHz
fRF = 900MHz
fIF = 140MHz
fLO = 760MHz
fRF = 1950MHz
fIF = 240MHz
fLO = 2190MHz SIZE COMMENTS
C1, C2 220pF 220pF 82pF 0402 AVX
C3 – – 4.7pF 0402 AVX
C4 100pF 100pF 100pF 0402 AVX
C5 10pF 10pF 10pF 0402 AVX
C6 1nF 1nF 1nF 0402 AVX
C7 1μF 1μF 1μF 0603 Taiyo Yuden LMK107BJ105MA
C8 3.3pF 1.8pF – 0402 AVX ACCU-P
C9 39pF 39pF 33pF 0402 AVX
C12 – – – 0402
C13 – 2.7pF – 0402
C14 – – 1.2pF 0402
L1, L2 100nH 100nH 100nH 0603 Coilcraft 0603CS
L3 18nH 12nH 1.8nH 0402 Toko LL1005-FHL
R1, R2 13.7, 0.1% 13.7, 0.1% 13.7, 0.1% 0603 IRC PFC-W0603LF-02-13R7-B
T1 4:1 4:1 4:1 AT224-1 Mini-Circuits TC4-1W+
TL1, TL2* – – 1.9mm – ZO = 70Ω
TL3 2.3mm 2.3mm 1.3mm – ZO = 70Ω
Z1 2.6pF 6.8pF 0Ω 0402 AVX/0Ω Jumper
*Center-to-center spacing between C9 and C3. Center of C9 is 3.0mm from the edge of the package.
GND
GND
GND
IF+
IF–
GND
GND
18
17
16
15
14
13
1
2
3
4
5
6
GND
GND
GND
RF
GND
GND
GND
GND
LO
GND
GND
GND
GND
VCC
VCC
VCC
VCC
GND
C3C9
C4
C1
IF
INPUT
RF
OUTPUT
T1
4:1
C2
L1
TL1
L2
R1
LO INPUT
R2
C5
789101112
24 23 22 21 20 19
C6 C7
VCC
C8
5578 F01
L3
C13
Z1
C12
C14
TL2 TL3
LT5578
10
5578f
APPLICATIONS INFORMATION
The LT5578 uses a high performance LO buffer amplifi er
driving a double-balanced mixer core to achieve frequency
conversion with high linearity. Internal baluns are used to
provide single-ended LO input and RF output ports. The
IF input is differential. The LT5578 is intended for opera-
tion in the 0.4GHz to 2.7GHz frequency range, though
operation outside this range is possible with reduced
performance.
IF Input Interface
The IF inputs are tied to the emitters of the double-balanced
mixer transistors, as shown in Figure 2. These pins are
internally biased to a common mode voltage of 565mV.
The optimum DC current in the mixer core is approximately
40mA per side, and is set by the external resistors, R1 and
R2. The inductors and resistors must be able to handle
the anticipated current and power dissipation. For best
LO leakage performance the board layout must be sym-
metrical and the input resistors should be well matched
(0.1% tolerance is recommended).
The purpose of the inductors (L1 and L2) is to reduce the
loading effects of R1 and R2. The impedances of L1 and
L2 should be at least several times greater than the IF input
impedance at the desired IF frequency. The self-resonant
frequency of the inductors should also be at least several
times the IF frequency. Note that the DC resistances of L1
and L2 will affect the DC current and should be accounted
for in the selection of R1 and R2.
L1 and L2 should connect to the signal lines as close to
the package as possible. This location will be at the lowest
impedance point, which will minimize the sensitivity of the
performance to the loading of the shunt L-R branches.
Capacitors C1 and C2 are used to cancel out the parasitic
series inductance of the IF transformer. They also provide
DC isolation between the IF ports to prevent unwanted inter-
actions that can affect the LO to RF leakage performance.
The differential input resistance to the mixer is approxi-
mately 10Ω, as indicated in Table 1. The package and
external inductances (TL1 and TL2) are used along with
C9 to step the impedance up to about 12.5Ω. At lower
frequencies additional series inductance may be required
between the IF ports and C9. The position of C9 may vary
with the IF frequency due to the different series inductance
requirements. The 4:1 impedance ratio of transformer T1
completes the transformation to 50Ω. Table 1 lists the
differential IF input impedances and refl ection coeffi cients
for several frequencies.
Table 1. IF Input Differential Impedance
FREQUENCY
(MHz)
IF INPUT
IMPEDANCE
REFLECTION COEFFICIENT
MAG ANGLE
70 10.0 + j1.1 0.666 177.4
140 10.2 + j1.5 0.661 176.5
170 8.7 + j1.8 0.705 175.7
190 8.7 + j2.0 0.705 175.2
240 8.7 + j2.5 0.705 174.0
380 8.7 + j3.9 0.704 170.9
450 8.7 + j4.5 0.705 169.3
750 9.6 + j7.6 0.683 162.0
1000 9.8 + j10.3 0.685 155.9
The purpose of capacitor C3 is to improve the LO-RF
leakage in some applications. This relatively small-valued
capacitor has little effect on the impedance match in most
cases. This capacitor should typically be located close to
the IC, however, there may be cases where re-positioning
the capacitor will improve performance.
The measured return loss of the IF input is shown in
Figure 3 for application frequencies of 70MHz, 140MHz
and 240MHz. Component values are listed in Table 2. All
of the applications use L1 = L2 = 100nH, R1 = R2 =13.7Ω
Figure 2. IF Input with External Matching
C3 VCC
40mA
565mV
565mV
40mA
2k
2k
IF+
LT5578
C9
C1
IF
INPUT T1
4:1
C2
L1
L2
R1
R2
5578 F02
3
IF–
4
TL1
TL2
LT5578
11
5578f
APPLICATIONS INFORMATION
and T1 = TC4-1W+. The 70MHz match was not used for
140MHz characterization because it requires the addition
of two inductors.
Table 2. IF Input Component Values
FREQUENCY
(MHz)
C1, C2
(pF)
C9
(pF)
C3
(pF)
TL1, TL2
(nH)
MATCH BW
(at 12dB RL)
70 560 82 – 3.3 50-215
140 220 39 – – 98-187
240 82 33 4.7 – 175-295
LO Input Interface
The simplifi ed schematic for the single-ended LO input port
is shown in Figure 4. An internal transformer provides a
broadband impedance match and performs single-ended
to differential conversion. The primary winding is internally
grounded, thus an external DC block may be necessary
in some applications. The transformer secondary feeds
the differential limiting amplifi er stages that drive the
mixer core.
The measured return loss of the LO input port is shown in
Figure 5 for different application frequencies. The imped-
ance match is acceptable from about 1.5GHz to beyond
3GHz, with a minimum return loss across this range of
about 9dB. Below 1.5GHz, external components are used
to tune the impedance match to the desired frequency.
Figure 3. IF Input Return Loss with 70MHz (a),
140MHz (b) and 240MHz (c) Matching
FREQUENCY (MHz)
50
–30
RETURN LOSS (dB)
–25
–20
–15
–10
0
100
ab
c
150 200 250
5578 F03
300 350
–5
Table 3 lists the input impedance and refl ection coeffi cient
vs frequency for the LO input for use in such cases.
Table 3. Single-Ended LO Input Impedance
(at Pin 22, No External Match)
FREQUENCY
(MHz)
LO INPUT
IMPEDANCE
REFLECTION COEFFICIENT
MAG ANGLE
300 41.7||j20.3 0.747 142.8
600 95.0||j42.7 0.657 105.5
900 126||j84.2 0.558 67.6
1200 127||j239 0.456 27.6
1500 104||–j686 0.353 –10.8
1800 74.0||–j188 0.247 –48.3
2100 52.5||–j162 0.158 –90.0
2400 42.3||–j459 0.097 –152.0
2700 44.4||j249 0.111 127.5
3000 52.4||j161 0.159 90.6
VBIAS
LO
C13 C12
5578 F04
LO
INPUT
EXTERNAL
MATCHING
22
Z1
Figure 4. LO Input Circuit
Figure 5. LO Input Return Loss with 520MHz (a),
760MHz (b), 880MHz (c) and >1.5GHz (d) Matching
FREQUENCY (MHz)
0
a
bc
d
–25
RETURN LOSS (dB)
–20
–15
–10
–5
0
500 1000 1500 2000
5578 F05
2500 3000
SEE FIGURES 1 AND 8 FOR
COMPONENT VALUES
LT5578
12
5578f
APPLICATIONS INFORMATION
RF Output Interface
The RF output interface is shown in Figure 6. An internal
RF transformer reduces the mixer core output impedance
to simplify matching of the RF output pin. A center tap in
the transformer provides the DC connection to the mixer
core and the transformer provides DC isolation to the RF
output. The RF pin is internally grounded through the
secondary winding of the transformer, thus a DC voltage
should not be applied to this pin.
While the LT5578 performs best at frequencies above
700MHz, the part can be used down to 400MHz. The low
inductance of the internal transformer limits the perfor-
mance at lower frequencies. The impedance data for the RF
output, listed in Table 4, can be used to develop matching
networks for different frequencies or load impedances.
Figure 7 illustrates the output return loss performance
for several applications. The component values and ap-
proximate matching bandwidths are listed in Table 5.
DC and RF Grounding
The LT5578 relies on the back side ground for both RF
and thermal performance. The Exposed Pad must be
soldered to the low impedance topside ground plane of
the board. As many vias as possible should connect the
topside ground to other ground layers to aid in thermal
dissipation and reduce inductance.
Table 4. Single-Ended RF Output Impedance
(at Pin 15, No External Matching)
FREQUENCY
(MHz)
RF OUTPUT
IMPEDANCE
REFLECTION COEFFICIENT
MAG ANGLE
400 10.1 + j29.3 0.741 117.6
800 90.8 + j96.6 0.614 32.6
1200 69.7 – j66.6 0.507 –44.4
1600 32.8 – j22.5 0.330 –112.3
2000 32.3 – j5.4 0.225 –159.3
2400 28.6 + j0.3 0.273 179.0
2800 22.5 + j4.4 0.384 167.3
Table 5. RF Output Component Values
FREQUENCY
(MHz) C8 (pF) L3 (nH) C14 (pF)
MATCH BW
(at 12dB RL)
450 9.0 18 – 430-505
740 3.3 18 – 680-768
900 1.8 12 – 835-970
1950 – 1.8 1.2 1765-2305
2600 – 0Ω 0.8 2150-2990
Figure 6. RF Output Circuit
Figure 7. RF Output Return Loss with 450MHz (a), 740MHz (b),
900MHz (c), 1950MHz (d) and 2600MHz (e) Matching
15
11
8 109
VCC
C8 C14
5578 F06
LT5578
L3
RF
50Ω
FREQUENCY (MHz)
0
ab
c
d
e
–25
RETURN LOSS (dB)
–20
–15
–10
–5
0
500 1000 1500 2000
5578 F07
2500 3000
LT5578
13
5578f
TYPICAL APPLICATIONS
The following examples illustrate the implementation and
performance of the LT5578 in some selected applications.
These circuits were evaluated using the board layout
shown in Figure 12.
450MHz Application
In this case, the LT5578 was evaluated for an application
with an IF input at 70MHz, an RF output of 450MHz and
a high side LO. The LO port is tuned for high side LO in-
jection at 520MHz. The matching networks for the three
ports are shown in Figure 8.
At the IF input, the 560pF capacitors are used mainly as
DC blocks, but also help tune out the parasitic inductance
of the transformer. The 82pF differential capacitor and
3.3nH chip inductors provide an impedance transforma-
tion between the IF input pins and the transformer. The
relatively low input frequency requires the use of chip
inductors instead of the short transmission lines that are
shown in Figure 2. The measured IF port return loss is
included in Figure 3.
The RF port impedance match is realized with a shunt 12pF
capacitor and a series 18nH inductor. The return loss with
this confi guration is better than 12dB from about 430MHz
to 505MHz and is plotted in Figure 7.
To tune the LO port, a series 6.8pF and shunt 4.7pF ca-
pacitor are used as shown. This combination provides a
10dB, or better, return loss from 435MHz to 580MHz as
shown in Figure 5. The series capacitor also provides DC
decoupling for the internal transformer at the LO input.
Figure 9 shows measured conversion gain, noise fi gure
and OIP3 as a function of RF output frequency. At 450MHz,
the gain is –2.1dB with a NF of 9.3dB and an OIP3 of
23.8dBm.
82pF
6.8pF
12pF
560pF
13.7Ω
100nH
100nH
TC4-1W+
4:1
560pF
3.3nH
3.3nH
IF
70MHz
RF
450MHz
LO
520MHz
18nH
13.7Ω
5578 F08
4.7pF
Figure 8. Schematic for 450MHz RF Application with 70MHz IF and 520MHz LO
RF OUTPUT FREQUENCY (MHz)
420
GAIN (dB), NF (dB)
OIP3 (dBm)
4
6
8
500
5578 F09
2
0
–4 440 460 480
–2
12
TA = 25°C
fIF = 70MHz
PIF = –5dBm/TONE
10
24
26
28
22
20
16
18
32
SSB NF
OIP3
GAIN
30
Figure 9. Gain, Noise Figure and OIP3 vs RF Frequency
in the 450MHz Application
2600MHz Application
For this application, the impedance match of the RF port is
optimized at 2600MHz and has a good return loss over the
range of 2200MHz to 2900MHz. The component values are
listed in Table 5 and typical output return loss is shown in
Figure 7. The IF input is matched at 240MHz as described
in Table 2. The LO port requires no external matching for
this band as its return loss is good for frequencies above
1.5GHz.
LT5578
14
5578f
TYPICAL APPLICATIONS
The measured room temperature performance is plotted
in Figure 10 for both low side and high side LO drive. At
2600MHz, the gain is approximately –2.8dB with a noise
fi gure of 11.2dB and OIP3 of about 22.2dBm. Low side
LO yields slightly better overall performance than high
side LO.
700 to 950 MHz Output Matching
The application shown on page 1 has a wider bandwidth
than the 740MHz and 900MHz confi gurations. Using two
additional components at the RF output allows the band-
width to be extended to cover the range from 700MHz to
950MHz. Figure 11 compares the broadband return loss
to the typical 740MHz and 900MHz return loss perfor-
mance.
The swept gain, noise fi gure and OIP3 results are plotted
on page 1 for an IF of 140MHz and a low side LO. The
conversion gain is greater than 0.7dB across the band with
OIP3 better than 25.5dBm. The single side-band noise
fi gure is less than 8.8dB across the band.
RF OUTPUT FREQUENCY (MHz)
2200
GAIN (dB), NF (dB)
OIP3 (dBm)
4
6
8
2700
5578 F09
2
0
–4 2300 2400 2500 2600
–2
12
10
24
26
28
22
20
16
18
32
SSB NF
OIP3
GAIN
30
LS LO
HS LO
Figure 10. Gain, Noise Figure and OIP3 vs RF Frequency
for the 2600MHz Application
FREQUENCY (MHz)
600
RETURN LOSS (dB)
–10
–5
0
1000
5578 F11
–15
–20
–25 700
ab
c
800 900 1100
Figure 11. Return Loss Comparison: 740MHz (a),
900MHz (b) and 700MHz to 950MHz (c)
Figure 12. LT5578 Evaluation Board (DC1545A)
LT5578
15
5578f
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
PACKAGE DESCRIPTION
UH Package
24-Lead Plastic QFN (5mm × 5mm)
(Reference LTC DWG # 05-08-1747 Rev A)
5.00 p 0.10
5.00 p 0.10
NOTE:
1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON THE TOP AND BOTTOM OF PACKAGE
PIN 1
TOP MARK
(NOTE 6)
0.55 p 0.10
23
1
2
24
BOTTOM VIEW—EXPOSED PAD
3.25 REF
3.20 p 0.10
3.20 p 0.10
0.75 p 0.05 R = 0.150
TYP
0.30 p 0.05
(UH24) QFN 0708 REV A
0.65 BSC
0.200 REF
0.00 – 0.05
0.75 p0.05
3.25 REF
3.90 p0.05
5.40 p0.05
0.30 p 0.05
PACKAGE OUTLINE
0.65 BSC
RECOMMENDED SOLDER PAD LAYOUT
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
PIN 1 NOTCH
R = 0.30 TYP
OR 0.35 s 45o
CHAMFER
R = 0.05
TYP
3.20 p 0.05
3.20 p 0.05
LT5578
16
5578f
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2009
LT 0709 • PRINTED IN USA
RELATED PARTS
PART NUMBER DESCRIPTION COMMENTS
Infrastructure
LT5514 Ultralow Distortion, IF Amplifi er/ADC Driver
with Digitally Controlled Gain
850MHz Bandwidth, 47dBm OIP3 at 100MHz, 10.5dB to 33dB Gain Control Range
LT5517 40MHz to 900MHz Quadrature Demodulator 21dBm IIP3, Integrated LO Quadrature Generator
LT5518 1.5GHz to 2.4GHz High Linearity Direct
Quadrature Modulator
22.8dBm OIP3 at 2GHz, –158.2dBm/Hz Noise Floor, 50Ω Single-Ended RF and LO
Ports, 4-Channel W-CDMA ACPR = –64dBc at 2.14GHz
LT5519 0.7GHz to 1.4GHz High Linearity Upconverting
Mixer
17.1dBm IIP3 at 1GHz, Integrated RF Output Transformer with 50Ω Matching,
Single-Ended LO and RF Ports Operation
LT5520 1.3GHz to 2.3GHz High Linearity Upconverting
Mixer
15.9dBm IIP3 at 1.9GHz, Integrated RF Output Transformer with 50Ω Matching,
Single-Ended LO and RF Ports Operation
LT5521 10MHz to 3700MHz High Linearity
Upconverting Mixer
24.2dBm IIP3 at 1.95GHz, NF = 12.5dB, 3.15V to 5.25V Supply, Single-Ended LO
Port Operation
LT5522 400MHz to 2.7GHz High Signal Level
Downconverting Mixer
4.5V to 5.25V Supply, 25dBm IIP3 at 900MHz, NF = 12.5dB, 50Ω Single-Ended RF
and LO Ports
LT5526 High Linearity, Low Power Downconverting
Mixer
3V to 5.3V Supply, 16.5dBm IIP3, 100kHz to 2GHz RF, NF = 11dB, ICC = 28mA,
–65dBm LO-RF Leakage
LT5527 400MHz to 3.7GHz High Signal Level
Downconverting Mixer
IIP3 = 23.5dBm and NF = 12.5dBm at 1900MHz, 4.5V to 5.25V Supply, ICC = 78mA,
Conversion Gain = 2dB
LT5528 1.5GHz to 2.4GHz High Linearity Direct
Quadrature Modulator
21.8dBm OIP3 at 2GHz, –159.3dBm/Hz Noise Floor, 50Ω, 0.5VDC Baseband
Interface, 4-Channel W-CDMA ACPR = –66dBc at 2.14GHz
LT5557 400MHz to 3.8GHz 3.3V Downconverting Mixer IIP3 = 23.5dBm at 3.6GHz, NF = 15.4dB, Conversion Gain = 1.7dB, 3.3V Supply at
82mA, Single-Ended RF and LO Inputs
LT5558 600MHz to 1100MHz High Linearity Direct
Quadrature Modulator
22.4dBm OIP3 at 900MHz, –158dBm/Hz Noise Floor, 3kΩ, 2.1VDC Baseband
Interface, 3-Ch CDMA2000 ACPR = –70.4dBc at 900MHz
LT5560 Ultra-Low Power Active Mixer 10mA Supply Current, 10dBm IIP3, 10dB NF, Usable as Up- or Down-Converter.
LT5568 700MHz to 1050MHz High Linearity Direct
Quadrature Modulator
22.9dBm OIP3 at 850MHz, –160.3dBm/Hz Noise Floor, 50Ω, 0.5VDC Baseband
Interface, 3-Ch CDMA2000 ACPR = –71.4dBc at 850MHz
LT5572 1.5GHz to 2.5GHz High Linearity Direct
Quadrature Modulator
21.6dBm OIP3 at 2GHz, –158.6dBm/Hz Noise Floor, High-Ohmic 0.5VDC Baseband
Interface, 4-Ch W-CDMA ACPR = –67.7dBc at 2.14GHz
LT5575 700MHz to 2.7GHz Direct Conversion I/Q
Demodulator
Integrated Baluns, 28dBm IIP3, 13dBm P1dB, 0.03dB I/Q Amplitude Match,
0.4° Phase Match
LT5579 1.5GHz to 3.8GHz High Linearity Upconverting
Mixer
27.3dBm OIP3 at 2.14GHz, NF = 9.9dB, 3.3V Supply, Single-Ended LO and RF Ports
RF Power Detectors
LT C
®
5505 RF Power Detectors with >40dB Dynamic Range 300MHz to 3GHz, Temperature Compensated, 2.7V to 6V Supply
LTC5507 100kHz to 1000MHz RF Power Detector 100kHz to 1GHz, Temperature Compensated, 2.7V to 6V Supply
LTC5508 300MHz to 7GHz RF Power Detector 44dB Dynamic Range, Temperature Compensated, SC70 Package
LTC5509 300MHz to 3GHz RF Power Detector 36dB Dynamic Range, Low Power Consumption, SC70 Package
LTC5530 300MHz to 7GHz Precision RF Power Detector Precision VOUT Offset Control, Shutdown, Adjustable Gain
LTC5531 300MHz to 7GHz Precision RF Power Detector Precision VOUT Offset Control, Shutdown, Adjustable Offset
LTC5532 300MHz to 7GHz Precision RF Power Detector Precision VOUT Offset Control, Adjustable Gain and Offset
LT5534 50MHz to 3GHz Log RF Power Detector with
60dB Dynamic Range
±1dB Output Variation over Temperature, 38ns Response Time, Log Linear
Response
LTC5536 Precision 600MHz to 7GHz RF Power Detector
with Fast Comparator Output
25ns Response Time, Comparator Reference Input, Latch Enable Input,
–26dBm to +12dBm Input Range
LT5537 Wide Dynamic Range Log RF/IF Detector Low Frequency to 1GHz, 83dB Log Linear Dynamic Range
LT5570 2.7GHz Mean-Squared Detector ±0.5dB Accuracy Over Temperature and >50dB Dynamic Range, Fast 500ns
Rise Time
LT5581 6GHz Low Power RMS Detector 40dB Dynamic Range, ±1dB Accuracy Over Temperature, 1.5mA Supply Current
