A pp li c at i on N ot e , R ev . 1. 2 , S e pt e m be r 2 00 7
A p p li c a t i o n N o t e N o . 1 2 3
L o w C o s t 2. 3 3 G H z C l a s s A S D A R S A c t i v e
A n te n n a A m p l i f i e r O ut p u t S ta g e u s i n g t h e I n f i ne o n
B FP 6 50 S i G e T ra n s i s t o r
R F & P r o t e c ti o n D e v i c e s
Edition 2007-09-03
Published by
Infineon Technologies AG
81726 München, Germany
© Infineon Technologies AG 2009.
All Rights Reserved.
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Application Note No. 123
Application Note No. 123
Revision History: 2007-09-03, Rev. 1.2
Previous Version: 2004-11-09, Rev. 1.1
Page
Subjects (major changes since last revision)
All
Document layout change
Application Note
3
Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
1
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier
Output Stage using the Infineon BFP650 SiGe Transistor
Applications
•
2.33 GHz “SDARS” Satellite Radio Active Antenna Output Stage
Overview
The Silicon-Germanium BFP650 SiGe Low Noise Transistor is shown in an SDARS active antenna LNA
application. The BFP650 is targeted for the output stage in a 2 or 3 stage LNA chain. A key parameter is
+20 dBm P1dB capability in the output stage. The demo board is standard FR4 material and "0402" case sizes
components are used throughout. A total of approximately 45 mm² of PCB area is required, and the total
component count, including the BFP650 and all passives, is 13.
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Figure 1
Block Diagram
Summary
Achieved 14.1 dB gain, 1.3 dB Noise Figure over the 2320 - 2345 MHz band, drawing 59.2 mA @ 3.3 V, or
53.1 mA @ 3.0 V. Noise figure result does NOT "back out" FR4 PCB losses - if PCB loss at LNA input were
extracted, Noise Figure result would be approximately 0.1 - 0.2 dB lower. Amplifier is unconditionally stable from
5 MHz to 6 GHz. Output P1dB = +19.6 dBm @ 3 V, or +18.7 dBm @ 3.0 V. Input 3rd Order Intercept = +21.1 dBm
@ 2332 MHz, 3.3 V, Output IP3 = +35.2 dBm @ 3.3 V.
Application Note
4
Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
PCB Cross - Section Diagram
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Schematic Diagram
Application Note
5
Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
Summary of Data
T = 25 °C, network analyzer source power = -25 dBm
Table 1
Summary of LNA Data
Parameter
Result
Comments
Frequency Range
Under 2320 to 2345 MHz
Covers both XM Radio and SIRIUS
frequency bands
DC Current
59.2 mA @ 3.0 V
53.2 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
14.2 dB @ 2320 MHz
14.1 dB @ 2332.5 MHz
14.1 dB @ 2345 MHz
Negligible change in gain or matching
at 3.3 or 3.0 V
Noise Figure
1.3 dB @ 2320 MHz
1.3 dB @ 2332.5 MHz
1.3 dB @ 2345 MHz
These values do NOT extract PCB
losses, etc. resulting from FR4 board
and passives used on PCB - these
results are at input SMA connector.
Input P1dB
+6.5 dBm @ 3.3 V
+5.6 dBm @ 3.0 V
Measured @ 2332.5 MHz. See pages
10 and 11.
Output P1dB
+19.6 dBm @ 3.3 V
+18.7 dBm @ 3.0 V
See pages 10 and 11.
Power Added Efficiency (PAE) at
1 dB Compression Point
44.4% @ 3.3 V
44.2% @ 3.0 V
PAE = (POUT - PIN) / (VCC x IC)
Decent results for a “Class A”
amplifier.
Input 3rd Order Intercept
+21.1 dBm @ 2332 MHz
See pages 17 and 18.
Measured at 3.3 V
Output 3rd Order Intercept
+35.1 dBm @ 2332 MHz
See pages 17 and 18.
Measured at 3.3 V
Input Return Loss
14.5 dB @ 2320 MHz
14.5 dB @ 2332.5 MHz
14.5 dB @ 2345 MHz
Output Return Loss
13.9 dB @ 2320 MHz
13.6 dB @ 2332.5 MHz
13.3 dB @ 2345 MHz
Reverse Isolation
18.0 dB @ 2320 MHz
17.9 dB @ 2332.5 MHz
17.9 dB @ 2345 MHz
Application Note
6
Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
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, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
Noise Figure, Tabular Data
2232.5 MHZ to 2442.5 MHz
From Rhode & Schwarz FSEK3 + FSEM30
System Preamplifier = MITEQ SMC-02
Table 2
Noise Figure
Frequency
Noise Figure
2232.5 MHz
1.34 dB
2245 MHz
1.33 dB
2257.5 MHz
1.35 dB
2270 MHz
1.32 dB
2282.5 MHz
1.34 dB
2295 MHz
1.33 dB
2307.5 MHz
1.34 dB
2320 MHz
1.33 dB
2332.5 MHz
1.30 dB
2345 MHz
1.29 dB
2357.5 MHz
1.30 dB
2370 MHz
1.31 dB
2382.5 MHz
1.31 dB
2395 MHz
1.30 dB
2407.5 MHz
1.31 dB
2420 MHz
1.32 dB
2432.5 MHz
1.32 dB
2442.5 MHz
1.29 dB
Application Note
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Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
Scanned Image of PC Board
Figure 5
Image of PC Board
Application Note
9
Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
Scanned Image of PC Board, Close-In Shot
Total PCB area used ≅ 45 mm²
Figure 6
Image of PC Board, Close-In Shot
Application Note
10
Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
Stability
Plots of Stability Factor "K" and Stability Measure "B1" from 5 MHz to 6 GHz. Plots are generated from real,
measured S parameters taken from the demo PC board, NOT a simulation. S parameters are exported from
Network Analyzer, then imported into Eagleware GENESYS software, which calculates and plots K and B1. Note
K>1 and B1 > 0, showing unconditional stability.
K is trace in red color (bottom trace) and is assigned to left vertical axis at bottom of page. Note K > 1.
“Glitch" at low frequencies e.g. < 100 MHz is due to lack of dynamic range in network analyzer - S parameter S12
becomes vanishingly small as one moves lower in frequency, which causes expression for calculating "K" to "blow
up”.
B1 is trace is blue in color (top trace) and is assigned to right vertical axis.
Figure 7
Plot of K(f) and B1(f)
Application Note
11
Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
Gain Compression Test
VCC = 3.3 V. Network Analyzer is set to "CW" mode - e.g. set to a single frequency, with power sweep. Input power
is swept from -18 dBm to +10 dBm at 2332.5 MHz. Amplifier hits Input 1 dB compression point (IP1dB) at +6.5 dBm
input power. A 20 dB pad is placed after the amplifier to prevent the network analyzer input from being "slammed"
with too much power. Note indicated gain shows approximately -6 dB + 20 dB (pad) = +14.1 dB when amplifier is
not in compression, and +13.1 dB at 1 dB compression point.
Output P1dB = +6.5 dBm + 13.1 dB gain = +19.6 dBm, or 91.2 mW.
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Figure 8
Plot of Gain Compression @ 3.3 Volts
Application Note
12
Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
Gain Compression Test
VCC = 3.0 V. Network Analyzer is set to "CW" mode - e.g. set to a single frequency, with power sweep. Input power
is swept from -18 dBm to +10 dBm at 2332.5 MHz. Amplifier hits Input 1 dB compression point (IP1dB) at +5.6 dBm
input power. A 20 dB pad is placed after the amplifier to prevent the network analyzer input from being "slammed"
with too much power. Note indicated gain shows approximately -6 dB + 20 dB (pad) = +14 dB when amplifier is
not in compression, and +13 dB at 1 dB compression point.
Output P1dB = +5.6 dBm + 13.1 dB gain = +18.7 dBm, or 74.1 mW.
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Figure 9
Plot of Gain Compression @ 3.0 Volts
Application Note
13
Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
Input Return Loss, Log Mag
5 MHz to 6 GHz Sweep
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Figure 10
Plot of Input Return Loss
Application Note
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Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
Input Return Loss, Smith Chart
Reference Plane = Input SMA Connector on PC Board
5 MHz to 6GHz
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Figure 11
Smith Chart of Input Return Loss
Application Note
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Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
Forward Gain, wide Sweep
5 MHz to 6 GHz
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Figure 12
Plot of Forward Gain
Application Note
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Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
Reverse Isolation
5 MHz to 6 GHz
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Figure 13
Plot of Reverse Isolation
Application Note
17
Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
Output Return Loss, Log Mag
5 MHz to 6 GHz
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Figure 14
Plot of Output Return Loss
Application Note
18
Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
Output Return Loss, Smith Chart
Reference Plane = Output SMA Connector on PC Board
5 MHz to 6 GHz
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Figure 15
Smith Chart of Output Return Loss
Application Note
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Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
Input Stimulus for Amplifier Two-Tone Test
f1 = 2332 MHz, f2 = 2333 MHz, -10 dBm each tone.
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Figure 16
Tow-Tone Test, Input Stimulus
Application Note
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Rev. 1.2, 2007-09-03
Application Note No. 123
Low Cost 2.33 GHz Class A SDARS Active Antenna Amplifier Output Stage
LNA Response to Two-Tone Test
Input IP3 = -10 + (62.2/2) = +21.1 dBm
Output IP3 = +21.1 dBm + 14.1 dB gain = +35.2 dBm
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Figure 17
Tow-Tone Test, LNA Response
Application Note
21
Rev. 1.2, 2007-09-03