Ap pl ica t io n N o te, Re v. 1 . 2, F e br ua ry 2 00 8
A p p li c a t i o n N o t e N o . 1 4 9
1 . 8 V , 2 .6 m A L o w N o i s e A m p l if i e r fo r 1 57 5 M H z
G P S L1 F r e q ue n c y w i t h t h e B F P 4 0 5 R F 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 2008-02-22
Published by
Infineon Technologies AG
81726 München, Germany
© Infineon Technologies AG 2009.
All Rights Reserved.
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Application Note No. 149
Application Note No. 149
Revision History: 2008-02-22, Rev. 1.2
Previous Version: 2005-09-23, Rev. 1.1
Page
Subjects (major changes since last revision)
All
Small changes in figure descriptions
Application Note
3
Rev. 1.2, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
1
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency
with the BFP405 RF Transistor
Overview
•
•
•
•
The low emitter-area BFP405 RF Transistor in SOT343 package is shown in a low-cost, low-power
consumption LNA targeted for systems having a 1.8 V voltage regulator.
Standard, low-cost "0402" size passives are used. Total PCB area needed is 50 mm²; total parts count,
including the BFP405F transistor, is 12 pieces.
Printed Circuit Board used is Infineon Part Number 640-061603 Rev A. Standard FR4 material is used in a
three-layer PCB. See cross-sectional diagram below.
The amplifier is unconditionally stable from 5 MHz to 8 GHz.
Summary of Results
T = 25 °C, Network Analyzer Source Power ≈ -25 dBm, VCC = 1.8 V, VCE = 1.5 V, IC = 2.6 mA, ZS = ZL = 50 Ω.
Table 1
Summary of Results
Frequency dB [s11]² dB [s21]² dB [s12]² dB [s22]² NF *
MHz
dB
IIP3
OIP3
IP1dB
OP1dB
dBm
dBm
dBm
dBm
1575
-5
+10.3
-23.0
-8.7
9.6
15.3
26.6
9.6
1.6
* PCB loss is not extracted, e-g- reference plane of measurement is at PCB input RF SMA connector. If PCB loss
were extracted, noise figure would improve by 0.1 - 0.2 dB, e.g. NF result would be lower / better.
PCB Cross - Section Diagram
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Figure 1
PCB - Cross Sectional Diagram
Application Note
4
Rev. 1.2, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
Schematic Diagram
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Figure 2
Schematic Diagram
Application Note
5
Rev. 1.2, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
Bill of Material
Table 2
Bill of Material
Designator
Value
Manufacturer
Case Size
Function
C1
100 pF
Various
0402
DC blocking, input. Using above SRF also
provides some net inductance.
C2
1.8 pF
Various
0402
DC block, output. Also influences output
and input match.
C3
0.1 µF
Various
0402
Decoupling, low frequency. Also improves
Third Order Intercept.
C4
3.3 pF
Various
0402
Decoupling, high frequency. Also
influences stability and output match.
C5
0.1 µF
Various
0402
Low frequency decoupling.
L1
27 nH
Murata LQP15M series
0402
RF choke at input, bring in DC bias to base.
L2
4.3 nH
Murata LQP15M series
0402
RF choke at output, influences matching.
L3
4.7 nH
Murata LQP15M series
0402
Input impedance matching.
R1
5.6 Ω
Various
0402
RF stability aid.
R2
27 kΩ
Various
0402
Sets DC operating point (DC bias).
R3
91 Ω
Various
0402
Sets DC operating point and provides some
negative DC feedback to stabilize DC
operating point over lot-to-lot variations in
device DC current gain, also helps to
stabilize DC operating point over
temperature.
Q1
-
Infineon Technologies
SOT343
BFP405 RF Transistor, B6HF process
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, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
Noise Figure, Plot. Center of Plot (x-axis) is 1575 MHz.
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Figure 3
Noise Figure
Application Note
7
Rev. 1.2, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
Noise Figure, Tabular Data
From Rohde & Schwarz FSEK3 + FSEM30 + System Preamplifier
System Preamplifier = MITEQ SMC-02
Table 3
Noise Figure
Frequency
Noise Figure
1555 MHz
1.63 dB
1560 MHz
1.62 dB
1565 MHz
1.62 dB
1570 MHz
1.61 dB
1575 MHz
1.62 dB
1580 MHz
1.61 dB
1585 MHz
1.61 dB
1590 MHz
1.62 dB
1595 MHz
1.63 dB
Application Note
8
Rev. 1.2, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
Scanned Image of PC Board
Figure 4
Image of PC Board
Application Note
9
Rev. 1.2, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
Scanned Image of PC Board, Close-In Shot.
Total PCB area is approximately 50 mm².
Figure 5
Image of PC Board, Close-In Shot
Application Note
10
Rev. 1.2, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
Amplifier Stability
T = 25 °C, VCC = 1.8 V, VCE = 1.5 V, I = 2.6 mA.
Stability Factor "K" is shown below from "screen shot" taken from Rohde and Schwarz ZVC network analyzer. ZVC
Vector Network Analyzer calculates and plots K in real time, from measured S parameters. Note that K>1 from
5 MHz to 8 GHz; amplifier is unconditionally stable over this range.
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Figure 6
Plot of K(f)
Application Note
11
Rev. 1.2, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
Gain Compression at 1575 MHz, T = 25 °C
Amplifier is checked for 1 dB compression point. An Agilent power meter was used to ensure accurate power
levels are measured (as opposed to using Vector Network Analyzer in "Power Sweep" mode).
Output P1dB ≅ -8.7 dBm; Input P1dB ≅ -8.7 dBm -(Gain - 1 dB) = -8.7 dBm - 14.3 dB = -23.0 dBm
Table 4
Gain Compression at 1575 MHz
POUT, dBm
Gain, dB
-15.0
15.3
-14.0
15.3
-13.0
15.2
-12.0
15.1
-11.0
15.0
-10.0
14.8
-9.0
14.4
-8.0
14.0
-7.0
13.2
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Figure 7
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Plot of BFP405 Gain Compression, 1575.4 MHz
Application Note
12
Rev. 1.2, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
Please Note - all plots are taken from Rohde and Schwarz ZVC Network Analyzer
T = 25 °C, source power ≈ -30 dBm.
Input Return Loss, Log Mag
5 MHz - 8 GHz Sweep
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Figure 8
Plot of Input Return Loss
Application Note
13
Rev. 1.2, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
Input Return Loss, Smith Chart
Reference Plane = Input SMA Connector on PC Board
5 MHz - 8 GHz Sweep
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Figure 9
Smith Chart of Input Return Loss
Application Note
14
Rev. 1.2, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
Forward Gain
5 MHz - 8 GHz Sweep
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Figure 10
Plot of Forward Gain
Application Note
15
Rev. 1.2, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
Reverse Isolation
5 MHz - 8 GHz
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Figure 11
Plot of Reverse Isolation
Application Note
16
Rev. 1.2, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
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, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
Output Return Loss, Smith Chart
Reference Plane = Output SMA Connector on PC Board
5 MHz - 8 GHz Sweep
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Figure 13
Smith Chart of Output Return Loss
Application Note
18
Rev. 1.2, 2008-02-22
Application Note No. 149
1.8 V, 2.6 mA Low Noise Amplifier for 1575 MHz GPS L1 Frequency with the
Amplifier Response to Two Tone Test
Input stimulus: f1 = 1575 MHz, f2 = 1576 MHz, -30 dBm each tone.
Input IP3 = -30 + (50.0 / 2) = -5.0 dBm
Output IP3 = -5.0 dBm + 15.3 dB gain = +10.3 dBm
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Figure 14
Tow-Tone Test, LNA Response
Application Note
19
Rev. 1.2, 2008-02-22