A p p l i c a t i o n N o t e , R e v . 1 . 2 , A ug us t 2 00 7
A p p li c a t i o n N o t e N o . 1 2 1
L o w N o i s e A m p l i f i e r f o r G P S A p p l i c at i o n s u s i ng
B FP 6 40 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 2007-08-14
Published by
Infineon Technologies AG
81726 München, Germany
© Infineon Technologies AG 2009.
All Rights Reserved.
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Application Note No. 121
Application Note No. 121
Revision History: 2007-08-14, Rev. 1.2
Previous Version: 2003-08-29, Rev. 1.1
Page
Subjects (major changes since last revision)
All
Small changes in figure descriptions
Application Note
3
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
1
Low Noise Amplifier for GPS Applications using BFP640 SiGe
Transistor
Overview
•
•
•
•
•
•
•
BFP640 used for 1575 MHz Global Positioning Satellite (GPS) Applications
BFP640 is investigated for use as an LNA for 1575 MHz GPS
Design Goals: Gain = 16 dB min, Noise Figure < 0.6 dB, Input / Output Return Loss 10 dB or better,
current < 10 mA from a 3.0 V power supply, Input P1dB > -14.8 dBm min
Printed Circuit Board used is Infineon Part Number 640-061603 Rev A. Standard FR4 material is used in a
three-layer PCB. Please refer to cross-sectional diagram.
Low-cost, standard "0402" case-size SMT passive components are used throughout. Please refer to
schematic and Bill Of Material. The LNA is unconditionally stable from 5 MHz to 6 GHz.
Total PCB area used for the single LNA stage is approximately 35 mm². Total Parts count, including the
BFP640 transistor, is 12.
Achieved ≅ 17 dB gain, 0.92 dB Noise Figure at 1575 MHz from 3.0 V supply drawing 8.3 mA.
Note noise figure result does NOT "back out" FR4 PCB losses - if the PCB loss at LNA input were extracted,
Noise Figure result would be approximately 0.2 dB lower. Amplifier is unconditionally stable from 5 MHz to
6 GHz. Input P1dB ≈ -13.1 dBm @ 1575.4 MHz. Outstanding Input Third Order Intercept of +7.7 dBm.
PCB Cross - Section Diagram
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PCB Cross - Section Diagram
Application Note
4
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Summary of Data
(T = 25 °C) Network analyzer source power = -25 dBm
Table 1
Summary of Data
Parameter
Result
Comments
Frequency Range
1525 - 1625 MHz
1575.42 MHz
DC Current
8.3 mA
DC Voltage, VCC
3.0 V
Gain
17.6 dB @ 1575.42 MHz
Noise Figure
0.92 dB @ 1575.42 MHz
See Noise Figure plots and tabular
data,Figure 3 and Table 3
Input P1dB
-13.1 dBm @ 1575.42 MHz
See input power sweep vs. gain plot,
Figure 7
Output P1dB
+3.5 dBm @ 1575.42 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)
rd
Input 3 Order Interception
rd
+7.7 dBm @ 1575.42 MHz
Output 3 Order Interception
+25.3 dBm @ 1575.42 MHz
Input Return Loss
11.2 dB @ 1575.42 MHz
Output Return Loss
10.3 dB @ 1575.42 MHz
Reserve Isolation
26.5 dB @ 1575.42 MHz
Application Note
5
See Figure 15 and Figure 16
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Bill of Material
Table 2
Bill Of Material
REFERENCE
DESIGNATOR
VALUE
MANUFACTURER
CASE
SIZE
FUNCTION
C1
22 pF
Various
0402
DC Blocking, Input
C2
1.5 pF
Various
0402
DC Block, Output. Also Influences
Output and Input Impedance Match
C3
0.1 µF
Various
0402
Decoupling, Low Frequency. Also
improves Third-Order Interception
C4*
22 pF
Various
0402
Decoupling (RF Short)
C5*
33 pF
Various
0402
Decoupling (RF Short)
C6*
0.1 µF
Various
0402
Decoupling, Low Frequency
L1
22 nH
Murata LQP15M Series
0402
RF Choke at Input
L2
5.1 nH
Murata LQP15M Series
0402
RF Choke + Impedance Match at
Output
R1
15 Ω
Various
0402
Stability Improvement
R2
39 kΩ
Various
0402
Brings Bias Current / Voltage into Base
of Transistor
R3
39 Ω
Various
0402
Provides some Negative Feedback for
DC BIAS / DC Operation Point to
Compensate for Variations in
Transistor DC Current Gain,
Temperature Variations, etc.
Q1
-
Infineon Technologies
SOT343 BFP640 B7HF Transistor
J1, J2
-
Johnson 142-0701-841
-
J3
-
AMP 5 Pin Header MTA-100 Series 640456-5 (standard pin
plating) or 641215-5 (gold
plated pins)
Application Note
6
RF Input / Output Connectors
DC Connector
Pins 1,5 = GROUND
Pin 3 = VCC
Pins 2,4 = no connection
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Schematic Diagram
For 1575 MHz LNA
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Schematic Diagram
Application Note
7
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Noise Figure, Plot. Center of Plot (x-axis) is 1575.42 MHz.
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Figure 3
Noise Figure
Application Note
8
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Noise Figure, Tabular Data
From Rhode & Schwarz FSEK3 + FSEB30
System Preamplifier = MITEQ SMC-02
Table 3
Noise Figure
Frequency
Noise Figure
1525.4 MHz
0.89 dB
1535.4 MHz
0.91 dB
1545.4 MHz
0.90 dB
1555.4 MHz
0.92 dB
1565.4 MHz
0.92 dB
1575.4 MHz
0.92 dB
1585.4 MHz
0.89 dB
1595.4 MHz
0.92 dB
1605.4 MHz
0.92 dB
1615.4 MHz
0.93 dB
1625.4 MHz
0.91 dB
Application Note
9
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Scanned Image of PC Board
Figure 4
Image of PC Board
Application Note
10
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Scanned Image of PC Board, Close-In Shot
Figure 5
Image of PC Board, Close-In Shot
Application Note
11
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Stability Factor “K” and Stability Measure “B1”
Note that if k > 1 and B1 >0, the amplifier is unconditionally stable. Measured LNA s-parameters were taken on a
Network Analyzer & then imported into GENESYS simulation package, which calculates and plots K and B1
Figure 6
Plots of K(f) and B1(f) (5 MHz - 6 GHz)
Application Note
12
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Power Sweep at 1575 MHz (CW)
Source Power (Input) Swept from -25 dBm to 0 dBm
Input P1dB ≅ -13.1 dBm
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Power Sweep
Application Note
13
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Input Return Loss, Log Mag
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Plot of Input Return Loss
Application Note
14
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Input Return Loss, Smith Chart
Reference Plane = Input SMA Connector on PC Board
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Figure 9
Smith Chart of Input Return Loss
Application Note
15
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Forward Gain, Wide Sweep
5 MHz to 6 GHz
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Plot of Forward Gain with Wide Sweep (5 MHz - 6 GHz)
Application Note
16
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Forward Gain, Narrow Sweep
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Figure 11
Plot of Forward Gain(5 MHz - 6 GHz)
Application Note
17
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Reverse Isolation
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Figure 12
Plot of Reverse Isolation
Application Note
18
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Output Return Loss, Log Mag
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Figure 13
Plot of Output Return Loss
Application Note
19
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Output Return Loss, Smith Chart
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Figure 14
Smith Chart of Output Return Loss
Application Note
20
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
Input Stimulus for Amplifier Two-Tone Test
f1 = 1575 MHz, f2 = 1576 MHz, -23 dBm each tone
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Figure 15
Input Stimulus for Amplifier Tow-Tone Test
Application Note
21
Rev. 1.2, 2007-08-14
Application Note No. 121
Low Noise Amplifier for GPS Applications using BFP640 SiGe Transistor
LNA Response to Two-Tone Test
Input IP3 = -23 + (61.4 / 2) = +7.7 dBm
Output IP3 =+7.7 dBm + 17.6 dB gain = +25.3 dBm
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Figure 16
LNA Response to Tow-Tone Test
Application Note
22
Rev. 1.2, 2007-08-14