AN134

A pp li c at io n N o t e, R e v . 1. 2 , N ov e m be r 2 00 7
A p p li c a t i o n N o t e N o . 1 3 4
L o w - C u r r e nt L o w N o i s e A m p l if i e r ( L N A ) f o r 1 5 7 5
M H z G l o b a l P o s i ti o n i n g S a t e l l i te ( G P S )
A p pl i c a t i o n s us i n g t h e S i G e B F P 6 4 0 T r a 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 2007-12-12
Published by
Infineon Technologies AG
81726 München, Germany
© Infineon Technologies AG 2009.
All Rights Reserved.
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Application Note No. 134
Application Note No. 134
Revision History: 2007-12-12, Rev. 1.2
Previous Version: 2003-08-28, Rev. 1.1
Page
Subjects (major changes since last revision)
All
Small changes in figure descriptions
Application Note
3
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
1
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global
Positioning Satellite (GPS) Applications using the SiGe BFP640
Transistor
Overview
•
•
•
•
•
•
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
4 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 13.
Achieved 15 dB gain, 0.95 dB Noise Figure at 1575 MHz from a 3.0 V supply, drawing 4.9 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 ≈ -18.7 dBm.
PCB Cross - Section Diagram
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PCB - Cross Sectional Diagram
Application Note
4
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Summary of LNA Data
T = 25 °C, Network analyzer source power = -25 dBm
Table 1
Summary of LNA Data
Parameter
Result
Frequency Range
1575.42 MHz
DC Current
4.9 mA
DC Voltage, VCC
3.0 V
Collector-Emitter Voltage, VCE
2.4 V
Comments
Target: 4 mA max.
BFP640: VCEmax = 4.0 V
Gain
15.2 dB @ 1575.42 MHz
Gain target: 16 dB min.
Noise Figure
0.95 dB @ 1575.42 MHz
See noise figure plots and tabular
data, Figure 3 and Table 3
(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
-18.7 dBm @ 1575.42 MHz
Target: -14.8 dBm. See input power
sweep vs. gain plot, Figure 7
Output P1dB
-4.5 dBm @ 1575.42 MHz
rd
Input 3 Order Intercept
-1.1 dBm @ 1575.42 MHz
Target: +2 dBm min.
See pages Figure 15 and
Figure 16.
Input Return Loss
9.3 dB @ 1575.42 MHz
10 dB min.
Output Return Loss
10.0 dB @ 1575.42 MHz
10 dB min.
Reverse Isolation
26.8 dB @ 1575.42 MHz
Application Note
5
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Bill of Material
Table 2
Bill of Material, Broadband BFP640 UHF Feedback LNA
Reference
Designator
Value
Manufacturer
Case Size
Function
C1
22 pF
Various
0402
DC blocking, input
C2
3.3 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 Intercept.
C4
22 pF
Various
0402
Decoupling (RF short)
C5
12 pF
Various
0402
Decoupling (RF short). Also has some
influence on stability (using less than 22 pF
causes output of amplifier to “see” more
loss from R1 at lower frequencies →
stability improvement).
C6
0.1 µF
Various
0402
Decoupling, low frequency
L1
22 nH
Murata LQP15M series
low-cost inductor
0402
RF choke at input
L2
6.8 nH
Murata LQP15M series
low-cost inductor
0402
RF choke + impedance match at output
L3
1.5 nH
Murata LQP15M series
low-cost inductor
0402
Input impedance match.
R1
43 Ω
Various
0402
Stability improvement
R2
56 kΩ
Various
0402
Bring bias current / voltage into base of
transistor
R3
82 Ω
Various
0402
Provides some negative feedback for DC
bias / DC operating 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
-
RF input / output connectors
J3
-
AMP 5 pin header MTA100 series 640456-5
(standard pin plating) or
641215-5 (gold plated
pins)
-
DC connector
Application Note
Pins 1, 5 = ground
Pin 3 = VCC
Pins 2, 4 = no connection
6
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Schematic Diagram for 1575 MHz LNA
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Figure 2
Schematic Diagram
Application Note
7
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Noise Figure, Plot, Center of Plot (x-axis) is 1575.4 MHz.
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Figure 3
Noise Figure
Application Note
8
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Noise Figure, Tabular Data
From Rohde & Schwarz FSEK3 + FSEB30
System Preamplifier = MITEQ SMC-02
Table 3
Noise Figure
Frequency
Noise Figure
1525.4 MHz
0.99 dB
1535.4 MHz
0.97 dB
1545.4 MHz
0.98 dB
1555.4 MHz
0.98 dB
1565.4 MHz
0.97 dB
1575.4 MHz
0.95 dB
1585.4 MHz
0.99 dB
1595.4 MHz
0.98 dB
1605.4 MHz
0.98 dB
1615.4 MHz
0.98 dB
1625.4 MHz
0.98 dB
Application Note
9
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Scanned Image of PC Board
Figure 4
Image of PC Board
Application Note
10
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Scanned Image of PC Board, Close-In Shot.
Figure 5
Image of PC Board, Close-In Shot
Application Note
11
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
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 and then imported into GENESYS simulation package, which calculates and plots K and B1.
Figure 6
Plot of K(f) and B1(f)
Application Note
12
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Power Sweep at 1575 MHz (CW)
Source Power (Input) Swept from -25 to 0 dBm
Input P1dB ≅ -18.7 dBm
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Figure 7
Plot of Power Sweep at 1575 MHz
Application Note
13
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Input Return Loss, Log Mag
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Figure 8
Plot of Input Return Loss
Application Note
14
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Input Return Loss, Smith Chart
Reference Plane = PCB Input SMA Connector
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Figure 9
Smith Chart of Input Return Loss
Application Note
15
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Forward Gain, Wide Sweep
5 MHz - 6 GHz
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Figure 10
Plot of Forward Gain (wide sweep)
Application Note
16
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Forward Gain, Narrow Sweep
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Figure 11
Plot of Forward Gain (narrow sweep)
Application Note
17
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Reverse Isolation
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Figure 12
Plot of Reverse Isolation
Application Note
18
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Output Return Loss, Log Mag
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Figure 13
Plot of Output Return Loss
Application Note
19
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Output Return Loss, Smith Chart
Reference Plane = PCB Output SMA Connector
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Figure 14
Smith Chart of Output Return Loss
Application Note
20
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Two-Tone Test, 1575 MHz
Input Stimulus for Amplifier Two-Tone Test.
f1 = 1575 MHz, f2 = 1576 MHz, -25 dBm each tone.
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Figure 15
Tow-Tone Test, LNA Response @ 1575 MHz
Application Note
21
Rev. 1.2, 2007-12-12
Application Note No. 134
Low-Current Low Noise Amplifier (LNA) for 1575 MHz Global Positioning
Two-Tone Test, 1575 MHz
LNA Response to Two-Tone Test.
Input IP3 = -25 + (47.8 / 2) = -1.1 dBm
Output IP3 = -1.1 dBm + 15.2 dB gain = +14.1 dBm
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Figure 16
Tow-Tone Test, LNA Response @ 1575 MHz
Application Note
22
Rev. 1.2, 2007-12-12
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