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 5
L o w N o i s e A m p l i fi e r ( L N A ) f o r 2 . 3 - 2 . 5 G H z
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 2007-12-19
Published by
Infineon Technologies AG
81726 München, Germany
© Infineon Technologies AG 2009.
All Rights Reserved.
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Application Note No. 135
Application Note No. 135
Revision History: 2007-12-19, Rev. 1.2
Previous Version: 2003-09-07, Rev. 1.1
Page
Subjects (major changes since last revision)
All
Small changes in figure descriptions
Application Note
3
Rev. 1.2, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
1
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the
SiGe BFP640 Transistor
Applications
•
2.3 GHz SDARS, 2.4 GHz (Bluetooth, WiLAN, other 2.4 GHz ISM band applications)
Overview
•
•
•
•
•
Design Goals: Gain = 15 dB, Noise Figure < 1.2 dB, Input / Output Return Loss 10 dB or better,
current < 7 mA from a 3.0 V power supply, Output P1dB > -15 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 15 dB gain, 0.96 dB Noise Figure at 2400 MHz from a 3.0 V supply, drawing 6.7 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 @ 2400 MHz. Outstanding Input Third Order Intercept of +11.6 dBm.
PCB Cross - Section Diagram
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Figure 1
PCB - Cross Sectional Diagram
Application Note
4
Rev. 1.2, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
Summary of LNA Data
T = 25 °C, Network analyzer source power = -25 dBm
Table 1
Summary of Results
Parameter
Result
Comments
Frequency Range
2300 - 2500 MHz
Covers SDARS 2.330 GHz band as
well as 2.4 GHz ISM band.
DC Current
6.7 mA
DC Voltage, VCC
3.0 V
Collector-Emitter Voltage, VCE
2.5 V
BFP640: VCEmax = 4.0 V
Gain
15.8 dB @ 2330 MHz
15.5 dB @ 2400 MHz
15.2 dB @ 2483 MHz
Gain target: 15 dB min.
Noise Figure
0.93 dB @ 2330 MHz
0.96 dB @ 2400 MHz
0.95 dB @ 2483 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
-11.3 dBm @ 2400 MHz
See input power sweep vs. gain plot,
Figure 7
Output P1dB
+3.2 dBm @ 2400 MHz
rd
Input 3 Order Intercept
+11.6 dB @ 2400 MHz
Input Return Loss
10.5 dB @ 2330 MHz
11.5 dB @ 2400 MHz
12.8 dB @ 2483 MHz
Output Return Loss
16.1 dB @ 2330 MHz
13.3 dB @ 2400 MHz
11.2 dB @ 2483 MHz
Reverse Isolation
21.9 dB @ 2330 MHz
21.7 dB @ 2400 MHz
21.5 dB @ 2483 MHz
Application Note
5
Two-Tone Test, see Figure 12 and
Figure 13
Rev. 1.2, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
Bill of Material
Table 2
Bill of Material, Broadband BFP640 UHF Feedback LNA
Reference
Designator
Value
Manufacturer
Case Size
Function
C1
8.2 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 Intercept.
C4
8.2 pF
Various
0402
Decoupling (RF short)
C5
5.6 pF
Various
0402
Decoupling (RF short). Also has some
influence on stability (using less than 8.2 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
12 nH
Murata LQP15M series
0402
RF choke at input
L2
3.9 nH
Murata LQP15M series
0402
RF choke + impedance match at output
R1
10 Ω
Various
0402
Stability improvement
R2
51 kΩ
Various
0402
Bring bias current / voltage into base of
transistor
R3
68 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, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
Schematic Diagram for 2.3 - 2.5 GHz LNA
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Figure 2
Schematic Diagram
Application Note
7
Rev. 1.2, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
Noise Figure, Plot, Center of Plot (x-axis) is 2400 MHz.
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Noise Figure
Application Note
8
Rev. 1.2, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
Noise Figure, Tabular Data
From Rohde & Schwarz FSEK3 + FSEB30
System Preamplifier = MITEQ SMC-02
Table 3
Noise Figure
Frequency
Noise Figure
2200 MHz
0.93 dB
2225 MHz
0.94 dB
2250 MHz
0.97 dB
2275 MHz
0.96 dB
2300 MHz
0.96 dB
2325 MHz
0.93 dB
2350 MHz
0.96 dB
2375 MHz
0.96 dB
2400 MHz
0.96 dB
2425 MHz
0.95 dB
2450 MHz
0.95 dB
2475 MHz
0.95 dB
2500 MHz
0.96 dB
2525 MHz
0.95 dB
2550 MHz
0.95 dB
2575 MHz
0.97 dB
2600 MHz
0.97 dB
Application Note
9
Rev. 1.2, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
Scanned Image of PC Board
Figure 4
Image of PC Board
Application Note
10
Rev. 1.2, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
Scanned Image of PC Board, Close-In Shot.
Figure 5
Image of PC Board, Close-In Shot
Application Note
11
Rev. 1.2, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
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, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
Power Sweep at 2400 MHz (CW)
Source Power (Input) Swept from -25 to 0 dBm
Input P1dB ≅ -11.3 dBm
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Figure 7
Plot of Power Sweep at 2400 MHz
Application Note
13
Rev. 1.2, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
Input Return Loss, Log Mag
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Figure 8
Plot of Input Return Loss
Application Note
14
Rev. 1.2, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
Forward Gain, Wide Sweep
5 MHz - 6 GHz
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Figure 9
Plot of Forward Gain
Application Note
15
Rev. 1.2, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
Reverse Isolation
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Figure 10
Plot of Reverse Isolation
Application Note
16
Rev. 1.2, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
Output Return Loss, Log Mag
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Figure 11
Plot of Output Return Loss
Application Note
17
Rev. 1.2, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
Two-Tone Test, 2400 MHz
Input Stimulus for Amplifier Two-Tone Test.
f1 = 2400 MHz, f2 = 2401 MHz, -17 dBm each tone.
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Figure 12
Tow-Tone Test, Input Stimulus @ 2400 MHz
Application Note
18
Rev. 1.2, 2007-12-19
Application Note No. 135
Low Noise Amplifier (LNA) for 2.3 - 2.5 GHz Applications using the SiGe
Two-Tone Test, 2400 MHz
LNA Response to Two-Tone Test.
Input IP3 = -17 + (57.1 / 2) = +11.6 dBm
Output IP3 = +11.6 dBm + 15.5 dB gain = +27.1 dBm
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Figure 13
Tow-Tone Test, LNA Response @ 2400 MHz
Application Note
19
Rev. 1.2, 2007-12-19