Application Note No. 145

Application Note, Rev. 1.2, February 2008
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active
Antenna Amplifier Output Stage using the Infineon
BFP450 Transistor
RF & Protection Devices
Edition 2008-02-21
Published by
Infineon Technologies AG
81726 München, Germany
© Infineon Technologies AG 2011.
All Rights Reserved.
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Application Note No. 145
Application Note No. 145
Revision History: 2008-02-21, Rev. 1.2
Previous Version: 2005-03-01, Rev. 1.1
Page
Subjects (major changes since last revision)
All
Small changes in figure descriptions
Application Note
3
Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
1
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier
Output Stage using the Infineon BFP450 Transistor
Overview
BFP450 SIEGET transistor is investigated as an alternative to the BFP650 SiGe Low Noise Transistor for the
output stage of an SDARS active antenna LNA. A key parameter is +20 dBm P1dB capability in the output stage.
The PCB used is standard FR4 material & "0402" case sizes components are used. A total of approximately
50 mm² of PCB area is required, the total component count, including the BFP450 and all passives, is 13. Net
result is: BFP450 provides slightly more available output power than BFP650 at comparable DC operating points;
however, BFP450 has less gain and higher noise figure. See table below. Both devices are in SOT343 package
with identical pin-outs. Note output power is "voltage limited" = e.g. if bias resistors were changed after power
supply voltage was increased, one should be able to hit +20 dBm OP1dB with less than 100 mA current.
Table 1
Comparison of BFP650 and BFP450 as SDARS active antenna output stage at 2.33 GHz
Device
DC Operating Point
Small Signal Gain,
dB
Output P1dB,
dBm
Noise Figure,
dB
BFP450
3 V, 76 mA, VCE = 2.7 V
9.8
+18.7
2.7
BFP450
3.7 V, 100 mA, VCE = 3.2 V 10.0
+20.5
Not tested
BFP650
3.0 V, 53 mA
≈ +18.0
1.3
14.1
Summary
•
•
Achieved 9.8 dB gain, 2.7 dB Noise Figure over the 2320 - 2345 MHz band, drawing 76 mA @ 3.0 V, or
100 mA @ 3.7 V. Amplifier is unconditionally stable from 5 MHz to 8 GHz. Output P1dB = +18.7 dBm @ 3 V,
76 mA or +20.5 dBm @ 3.7 V, 100 mA.
BFP450 seems to show a slight advantage in Output P1dB as compared to the BFP650. However, gain of
BFP450 in same PC board is approx. 4 dB lower, and noise figure of BFP450 is 1.4 dB higher.
Block Diagram of Application
Typical SDARS Active Antenna LNA
2320 - 2332.5 MHz (SIRIUS, 3 Stages)
2332.5 - 2345 MHz (XM Radio, 2 Stages)
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Figure 1
Block Diagram of Application
Application Note
4
Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
PC Board Cross Sectional Diagram
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Schematic Diagram
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Schematic Diagram
Application Note
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Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
Summary of Data
T = 25 °C, Network analyzer source power ≈ -30 dBm
Table 2
Summary of Results
Parameter
Result
Comments
Frequency Range
Under 2320 to 2345 MHz
Covers both XM Radio and SIRIUS
frequency bands.
DC Current
100 mA @ 3.7 V
76 mA @ 3.0 V
Note power supply voltage is
measured directly across PCB
supply line and ground, to eliminate
voltage drop across wire harness.
Gain
9.8 dB @ 2332.5 MHz
Noise Figure
2.7 dB @ 2332.5 MHz
These values do not extract PCB
losses, etc. resulting from FR4
board an passives used on PCB these results are at input SMA
connector.
Input P1dB
+11.7 dBm @ 3.7 V
+9.9 dBm @ 3.0 V
Measured @ 2332.5 MHz. See
Table 4 and Table 5.
Output P1dB
+20.5 dBm @ 3.7 V
+18.7 dBm @ 3.0 V
See Table 4 and Table 5.
Collector Efficiency at 1 dB
Compression Point
30.3 % @ 3.7 V
32.5 % @ 3.0 V
Decent results for a Class A
amplifier
Input 3rd Order Intercept
+22.9 dBm @ 2332 MHz
Figure 14 and Figure 15. Measured
at 3.0 V.
Output 3rd Order Intercept
+32.6 dBm @ 2332 MHz
Figure 14 and Figure 15. Measured
at 3.0 V.
Input Return Loss
9.0 dB @ 2332.5 MHz
Output Return Loss
9.8 dB @ 2332.5 MHz
Reverse Isolation
14.6 dB @ 2332.5 MHz
Application Note
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Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
Noise Figure, Plot, 2232.5 MHz to 2432.5 MHz, Center of Plot (x-axis) is 2332.5 MHz.
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Figure 4
Noise Figure
Application Note
7
Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
Noise Figure, Tabular Data
From Rohde & Schwarz FSEK3 + FSEM30
System Preamplifier = MITEQ SMC-02
Table 3
Noise Figure
Frequency
Noise Figure
2232.5 MHz
2.85 dB
2242.5 MHz
2.82 dB
2252.5 MHz
2.84 dB
2262.5 MHz
2.79 dB
2272.5 MHz
2.77 dB
2282.5 MHz
2.75 dB
2292.5 MHz
2.72 dB
2302.5 MHz
2.73 dB
2312.5 MHz
2.70 dB
2322.5 MHz
2.65 dB
2332.5 MHz
2.72 dB
2342.5 MHz
2.60 dB
2352.5 MHz
2.62 dB
2362.5 MHz
2.62 dB
2372.5 MHz
2.56 dB
2382.5 MHz
2.55 dB
2392.5 MHz
2.53 dB
2402.5 MHz
2.57 dB
2412.5 MHz
2.51 dB
2422.5 MHz
2.52 dB
2432.5 MHz
2.51 dB
Application Note
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Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
Scanned Image of PC Board
Figure 5
Image of PC Board
Application Note
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Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
Scanned Image of PC Board, Close-In Shot.
Total PCB area used ≅ 50 mm².
Figure 6
Image of PC Board, Close-In Shot
Application Note
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Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
Stability
Rohde and Schwarz ZVC Network Analyzer calculates and plots Stabilty Factor "K" in real time. Note minimum K
value is approximately 1.04 over the 5 MHz to 8 GHz range. Since inductive emitter degeneration is used,
S parameters should be measured up to at least 15 GHz to verify K > 1, B1 > 0 up to 15 GHz.
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Figure 7
Plot of K(f)
Application Note
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Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
Gain Compression
Amplifier is checked for 1 dB compression point at VCC = 3.0 V, I = 76 mA (with VCE = 2.7 V), and at VCC = 3.7 V,
I = 100 mA (with VCE = 3.2 V). An Agilent power meter was used to ensure accurate power levels are measured
(as opposed to using Vector Network Analyzer in "Power Sweep" mode).
For 3.0 V power supply voltage ⇒ OP1dB ≅ +18.7 dBm, or 74.1 mW
Collector efficiency at this point is 74.1 mW / (3 V x 76 mA) = 32.5 %
For 3.7 V power supply voltage ⇒ OP1dB ≅ +20.5 dBm, or 112.2 mW
Collector efficiency at this point is 112.2 mW / (3.7 V x 100 mA) = 30.3 %
Table 4
3.0 V, 76 mA
PIN, dBm
POUT, dBm
Gain
0
+9.9
9.9
+5.0
+14.8
9.8
+6.0
+15.8
9.8
+7.0
+16.6
9.6
+8.0
+17.5
9.5
+9.0
+18.2
9.2
+10.0
+18.8
8.8
+11.0
+19.2
8.2
Table 5
3.7 V, 100 mA
PIN, dBm
POUT, dBm
Gain
0
+10.1
10.1
+5.0
+15.0
10.0
+6.0
+16.0
10.0
+7.0
+16.9
9.9
+8.0
+17.8
9.8
+9.0
+18.7
9.7
+10.0
+19.5
9.5
+11.0
+20.3
9.3
+12.0
+20.9
8.9
Application Note
12
Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
Please Note - all plots are taken from ZVC Network Analyzer with amplifier DC bias set to 3.0 V, 76 mA.
Input Return Loss, Log Mag
5 MHz - 8 GHz
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Figure 8
Plot of Input Return Loss
Application Note
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Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
Input Return Loss, Smith Chart
Reference Plane = Input SMA Connector on PC Board
5 MHz - 8 GHz
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Figure 9
Smith Chart of Input Return Loss
Application Note
14
Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
Forward Gain, Wide Sweep
5 MHz - 8 GHz
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Figure 10
Plot of Forward Gain
Application Note
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Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
Reverse Isolation
5 MHz - 8 GHz
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Figure 11
Plot of Reverse Isolation
Application Note
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Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
Output Return Loss, Log Mag
5 MHz - 8 GHz
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Figure 12
Plot of Output Return Loss
Application Note
17
Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
Output Return Loss, Smith Chart
Reference Plane = Output SMA Connector on PC Board
5 MHz - 8 GHz
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Figure 13
Smith Chart of Output Return Loss
Application Note
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Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
Two Tone Test
Input Stimulus for Amplifier Two-Tone Test:
f1 = 2332 MHz, f2 = 2333 MHz, -10 dBm each tone.
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Figure 14
Tow-Tone Test, Input Stimulus
Application Note
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Rev. 1.2, 2008-02-21
Application Note No. 145
Low Cost, 3 V, 2.33 GHz Class A SDARS Active Antenna Amplifier Output
LNA Response to Two Tone Test
3.0 V, 76 mA for LNA.
Input IP3 = -10 + (65.5 / 2) = +22.8 dBm
Output IP3 = +22.8 dBm + 9.8 dB gain = +32.6 dBm
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Figure 15
Tow-Tone Test, LNA Response
Application Note
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Rev. 1.2, 2008-02-21