AN180

BF P540 F ES D
BF P540 F ES D E SD - Har den ed RF
Transis tor wit h 1k V HB M E S D Ra ting
in Lo w G a in 2. 4 GH z LN A
Applic atio n wi th s ho rt T urn - O n Tu rn Off Ti me
For Blu eT ooth and othe r 2. 4 G Hz
Applic atio ns re quiri ng lo w to
mo der ate gain and f as t s witc h ing
speed
Applic atio n N ote A N 180
Revision: Rev. 1.2
2011-05-31
RF and P r otecti on D evic es
Edition 2011-05-31
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2011 Infineon Technologies AG
All Rights Reserved.
Legal Disclaimer
The information given in this document shall in no event be regarded as a guarantee of conditions or
characteristics. With respect to any examples or hints given herein, any typical values stated herein and/or any
information regarding the application of the device, Infineon Technologies hereby disclaims any and all
warranties and liabilities of any kind, including without limitation, warranties of non-infringement of intellectual
property rights of any third party.
Information
For further information on technology, delivery terms and conditions and prices, please contact the nearest
Infineon Technologies Office (www.infineon.com).
Warnings
Due to technical requirements, components may contain dangerous substances. For information on the types in
question, please contact the nearest Infineon Technologies Office.
Infineon Technologies components may be used in life-support devices or systems only with the express written
approval of Infineon Technologies, if a failure of such components can reasonably be expected to cause the
failure of that life-support device or system or to affect the safety or effectiveness of that device or system. Life
support devices or systems are intended to be implanted in the human body or to support and/or maintain and
sustain and/or protect human life. If they fail, it is reasonable to assume that the health of the user or other
persons may be endangered.
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Application Note AN180
Revision History: 2011-05-31
Previous Revision: prev. Rev. 1.1
Page
Subjects (major changes since last revision)
New Layout
Trademarks of Infineon Technologies AG
A-GOLD™, BlueMoon™, COMNEON™, CONVERGATE™, COSIC™, C166™, CROSSAVE™, CanPAK™,
CIPOS™, CoolMOS™, CoolSET™, CONVERPATH™, CORECONTROL™, DAVE™, DUALFALC™,
DUSLIC™, EasyPIM™, EconoBRIDGE™, EconoDUAL™, EconoPACK™, EconoPIM™, E-GOLD™,
EiceDRIVER™, EUPEC™, ELIC™, EPIC™, FALC™, FCOS™, FLEXISLIC™, GEMINAX™, GOLDMOS™,
HITFET™, HybridPACK™, INCA™, ISAC™, ISOFACE™, IsoPACK™, IWORX™, M-GOLD™, MIPAQ™,
ModSTACK™, MUSLIC™, my-d™, NovalithIC™, OCTALFALC™, OCTAT™, OmniTune™, OmniVia™,
OptiMOS™, OPTIVERSE™, ORIGA™, PROFET™, PRO-SIL™, PrimePACK™, QUADFALC™, RASIC™,
ReverSave™, SatRIC™, SCEPTRE™, SCOUT™, S-GOLD™, SensoNor™, SEROCCO™, SICOFI™,
SIEGET™, SINDRION™, SLIC™, SMARTi™, SmartLEWIS™, SMINT™, SOCRATES™, TEMPFET™,
thinQ!™, TrueNTRY™, TriCore™, TRENCHSTOP™, VINAX™, VINETIC™, VIONTIC™, WildPass™,
X-GOLD™, XMM™, X-PMU™, XPOSYS™, XWAY™.
Other Trademarks
AMBA™, ARM™, MULTI-ICE™, PRIMECELL™, REALVIEW™, THUMB™ of ARM Limited, UK. AUTOSAR™
is licensed by AUTOSAR development partnership. Bluetooth™ of Bluetooth SIG Inc. CAT-iq™ of DECT
Forum. COLOSSUS™, FirstGPS™ of Trimble Navigation Ltd. EMV™ of EMVCo, LLC (Visa Holdings Inc.).
EPCOS™ of Epcos AG. FLEXGO™ of Microsoft Corporation. FlexRay™ is licensed by FlexRay Consortium.
HYPERTERMINAL™ of Hilgraeve Incorporated. IEC™ of Commission Electrotechnique Internationale. IrDA™
of Infrared Data Association Corporation. ISO™ of INTERNATIONAL ORGANIZATION FOR
STANDARDIZATION. MATLAB™ of MathWorks, Inc. MAXIM™ of Maxim Integrated Products, Inc.
MICROTEC™, NUCLEUS™ of Mentor Graphics Corporation. Mifare™ of NXP. MIPI™ of MIPI Alliance, Inc.
MIPS™ of MIPS Technologies, Inc., USA. muRata™ of MURATA MANUFACTURING CO. OmniVision™ of
OmniVision Technologies, Inc. Openwave™ Openwave Systems Inc. RED HAT™ Red Hat, Inc. RFMD™ RF
Micro Devices, Inc. SIRIUS™ of Sirius Sattelite Radio Inc. SOLARIS™ of Sun Microsystems, Inc. SPANSION™
of Spansion LLC Ltd. Symbian™ of Symbian Software Limited. TAIYO YUDEN™ of Taiyo Yuden Co.
TEAKLITE™ of CEVA, Inc. TEKTRONIX™ of Tektronix Inc. TOKO™ of TOKO KABUSHIKI KAISHA TA.
UNIX™ of X/Open Company Limited. VERILOG™, PALLADIUM™ of Cadence Design Systems, Inc. VLYNQ™
of Texas Instruments Incorporated. VXWORKS™, WIND RIVER™ of WIND RIVER SYSTEMS, INC. ZETEX™
of Diodes Zetex Limited.
Last Trademarks Update 2009-10-19
Application Note AN180, Rev. 1.2
3 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
List of Content, Figures and Tables
Table of Content
1
1.1
Overview ............................................................................................................................................. 5
Summary of Performance Data ............................................................................................................ 5
2
2.1
2.2
Schematic Diagram and Bill of Material ........................................................................................... 6
Schematic Diagram .............................................................................................................................. 6
Bill of Material ....................................................................................................................................... 7
3
3.1
3.2
3.3
3.3.1
3.3.2
3.3.3
3.3.4
3.4
3.5
3.5.1
3.5.2
Measurement Data ............................................................................................................................. 8
Noise Figure ......................................................................................................................................... 8
Amplifier Compression Point Measurement ....................................................................................... 10
Amplifier Stability, Gain, Return Loss and Reverse Isolation Plots ................................................... 11
Stability ............................................................................................................................................... 11
Input Return Loss ............................................................................................................................... 12
Forward Gain and Reverse Isolation ................................................................................................. 13
Output Return Loss ............................................................................................................................ 14
Amplifier Third Order Intercept (TOI) Measurement .......................................................................... 15
Amplifier Turn-On / Turn-Off Time Measurements ............................................................................ 16
Turn On Time ..................................................................................................................................... 17
Turn-Off Time ..................................................................................................................................... 18
4
Evaluation Board .............................................................................................................................. 19
5
References ........................................................................................................................................ 20
Author ................................................................................................................................................ 20
List of Figures
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
Block diagram of an example Bluetooth receiver system .................................................................... 5
Schematic diagram............................................................................................................................... 6
Noise figure plot ................................................................................................................................... 8
Gain compression at 2441 MHz, VCC = +2.8 V, I = 5.0 mA, VCE = 2.5 V, T = 25 °C .......................... 10
Amplifier stability: Plot of Stability Factor µ1 ...................................................................................... 11
Input return loss / dB .......................................................................................................................... 12
Input return loss (Smith chart) ............................................................................................................ 12
Forward Gain / dB .............................................................................................................................. 13
Reverse Isolation / dB ........................................................................................................................ 13
Output return loss / dB ....................................................................................................................... 14
Output return loss (Smith chart) ......................................................................................................... 14
Output spectrum of LNA during test ................................................................................................... 15
Turn-on / turn-off time: Test setup ...................................................................................................... 16
Screen shot: Turn on time .................................................................................................................. 17
Screen shot: Turn on time .................................................................................................................. 18
PCB cross section .............................................................................................................................. 19
View of entire PC board ..................................................................................................................... 19
Close-in view of LNA section ............................................................................................................. 19
List of Tables
Table 1
Table 2
Table 3
Summary of performance data T=25 °C, network analyzer source power = -25 dBm, VCC = 2.8 V,
VCE = 2.5 V, IC=5.0 mA ......................................................................................................................... 5
Bill-of-Material ...................................................................................................................................... 7
Noise figure, tabular data ..................................................................................................................... 9
Application Note AN180, Rev. 1.2
4 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Overview
1
Overview
Infineon Technologies BFP540FESD is an ESD-hardened, high gain, low noise Silicon RF Transistor suitable
for a wide range of Low Noise Amplifier (LNA) applications. The BFP540FESD is rated to survive up to 1000 V
ESD events between any pair of terminals, per the Human Body Model (HBM). Refer to Reference [1],
BFP540FESD datasheet, and refer to Refernce [2] for details on how the BFP540FESD sand similar Infineon
RF transistors achieve improved ESD-robustness.
The circuit shown is targeted for higher sensitivity or longer range BlueTooth and similar applications.
Commercially available fully integrated CMOS BlueTooth transceiver chips may claim receiver sensitivity
numbers which are far higher than real-world implementations permit. Losses in the bandpass filter (see block
diagram below) are often higher than claimed due to non-ideal effects. Therefore, to improve receiver sensitivity,
some (external) gain is required just after the antenna. However, too much external LNA gain compromises the
large-signal handling capability of the BlueTooth receiver. We want just enough gain to dominate the overall
system noise figure, no more. The LNA shown in this applications note is an attempt to achieve such a balance,
with a gain of between 8 dB and 9 dB. LNAs for this application must be able to switch on / off within about 1 µs
(1000 ns). The charge storage (capacitance) used in this circuit is minimized to reduce on / off times. Trade-off
for reduced capacitance values is a reduction in Third Order Intercept (IP3) performance. Inductive emitter
degeneration is used to improve amplifier low-frequency stability and impedance matching. Refer to
Reference [3] for a general overview of charge storage and inductive emitter degeneration.
Losses in filter section
degrade sensitivity
thus external LNA is
sometimes needed
BlueTooth CMOS
RFIC
Differential Interface
Low Noise Amplifier
Low / Moderate Gain
BFP540FESD
Mixed-Mode
Bandpass Filter
(Single Ended Input,
Balanced Output)
Figure 1
Block diagram of an example Bluetooth receiver system
1.1
Summary of Performance Data
Table 1
To MIC / Speaker
Summary of performance data
T=25 °C, network analyzer source power = -25 dBm, VCC = 2.8 V, VCE = 2.5 V, IC=5.0 mA
2
2
Frequency
(MHz)
dB[s11]
2400
-10.0
8.9
-23.9
2441
-10.3
8.7
-23.9
2483.5
-10.5
8.5
-23.8
dB[s21]
dB[s12]
2
2
1
IIP3
(dBm)
IP1dB
(dBm)
-10.2
NF
(dB)
1.4
-10.1
1.4
-6.3
-13.6
-10.0
1.4
dB[s22]
Amplifier is unconditionally Stable (µ1 > 1.0) from 50 MHz to 12 GHz.
External parts count (not including BFP540FESD transistor) = 14; 6 capacitors, 6 resistors, and 2 chip inductors.
All passives are 0402 case size. BFP540FESD transistor package is RoHS – compliant and measures
3
1.4 x 1.2 x 0.55 mm .
1
Does not extract PCB loss. If PCB loss (at input) were extracted, NF would be ~0.1 dB lower.
Application Note AN180, Rev. 1.2
5 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Schematic Diagram and Bill of Material
2
Schematic Diagram and Bill of Material
2.1
Schematic Diagram
Inductors are Murata LQP15M Series
(formerly LQP10A) 0402 case size.
Capacitors and resistors are 0402 case size.
J3
DC Connector
V
cc
= 2.8 V
PCB = 740F-080930 Rev A
PC Board Material = Standard FR4
I = 5.0 mA
= 50 ohm microstripline
14 external passives used:
6 capacitors
2 inductors
6 resistors
R2
36K
C3
8.2pF
C4
33pF
R1
13 ohms
L1
15nH
J1
RF
INPUT
C1
0.5pF
R3
39 ohms
C2
8.2pF
C5
6.8pF
L2
Q1
5.1nH
BFP540FESD
ESD-Hardened
Transistor
Q1: VCE = 2.5 V
W
L
C6
1.0pF
R4
8.2
ohms
R5
8.2
ohms
J2
RF OUTPUT
R6
150
ohms
3 dB attenuator
“Tee-pad”
(for gain reduction)
Figure
2 Emitter
Schematic
diagramfor low frequency stability improvement, impedance matching.
Inductive
Degeneration
One identical microstrip track from each of the two emitter leads to a separate ground via hole
is used. Ground hole via diameter is 0.012 inch / 0.3mm. Microstrip inductor dimensions are:
Inductive
degeneration
is used
for / low
frequency
stability
improvement
and impedance
matching. One
W = 0.010emitter
inch / 0.25
mm; L = 0.023
inch
0.584
mm, height
“h” between
top layer
RF traces and
identical
microstrip
track
from
each
of
the
two
emitters
leads
to
a
separate
ground
via
hole
is
used.
Ground hole
internal ground plane is 0.012 inch / 0.3mm. Note if spacing in the user‟s PCB between top
via
diameter
is
0.012
inch
(0.3
mm).
layer RF traces and internal ground plane is substantially greater than 0.012 inch / 0.3 mm, e.g.
0.062 inchdimensions
/ 1.6 mm thick,
the= additional
hole
inductance
the(0.584
thickermm).
PCB will suffice by
Microstrip
are: W
0.010 inch via
(0.25
mm);
L = 0.023ofinch
itself, and the microstrip inductors can be eliminated entirely.
Height between top layer RF traces and internal ground plane is 0.012 inch (0.3 mm). Note if spacing in the
user’s PCB between top layer RF traces and internal ground plane is substantially greater than 0.012 inch
(0.3 mm), for example 0.062 inch (1.6 mm) thick, the additional via hole inductance of the thicker PCB will
suffice by itself, and the microstrip inductors can be eliminated entirely.
Application Note AN180, Rev. 1.2
6 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Schematic Diagram and Bill of Material
2.2
Bill of Material
Table 2
Bill-of-Material
Symbol
Value
Unit
Size
Manufacturer
C1
0.5
pF
0402
Various
Impedance matching, input
C2
8.2
pF
0402
Various
RF decoupling / blocking cap
C3
8.2
pF
0402
Various
RF decoupling / blocking cap
C4
33
pF
0402
Various
RF decoupling / blocking cap
C5
16.8
pF
0402
Various
RF decoupling / blocking cap; also
influences output match and amplifier
stability margin
C6
1.0
pF
0402
Various
L1
15
nH
0402
Murata LQP
L2
5.1
nH
0402
Murata LQP
Output DC blocking cap; also improves
input match due to nonzero s21 of
transistor
RF choke at LNA input (for DC bias to
base)
RF choke at LNA output, for DC bias to
collector. Also influences matching and
stability
R1
13
Ω
0402
Various
RF stability improvement
R2
36
kΩ
0402
Various
DC biasing (base current)
R3
39
Ω
0402
Various
DC biasing; provides DC negative
feedback to stabilize DC operating point
over temperature vartiation, transistor
hFE variation, etc.
R4
8.2
Ω
0402
Various
For 3 dB “Tee” attenuator
R5
8.2
Ω
0402
Various
For 3 dB “Tee” attenuator
R6
150
BFP540FESD
Ω
Various
For 3 dB “Tee” attenuator
Q1
Application Note AN180, Rev. 1.2
0402
TSPF-4
Comment
Infineon Technologies LNA active device
7 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Measurement Data
3
Measurement Data
3.1
Noise Figure
Rohde & Schwarz FSEK3
02 Apr 2009
Noise Figure Measurement
EUT Name:
Manuf acturer:
Operating Conditions:
Operator Name:
Test Specification:
Comment:
BFP540FESD, Low Gain, Fast Switching / Fast Turn ON-OFF Time
Infineon Technologies
T=25 C, V = 2.8V, Vce = 2.5V, I = 5.0mA
Gerard Wevers
BlueTooth LNA
PCB = 740F-080930 RevA ; Preamp = MITEQ SMC-02
2 April 2009
Analyzer
RF Att:
Ref Lvl:
0.00 dB
-50.00 dBm
RBW :
VBW :
1 MHz
100 Hz
Range:
30.00 dB
Ref Lvl auto:
ON
Measurement
2nd stage corr:
ON
Mode:
Direct
ENR: 346A_1.ENR
Noise Figure /dB
1.90
1.80
1.70
1.60
1.50
1.40
1.30
1.20
1.10
1.00
0.90
2300 MHz
Figure 3
30 MHz / DIV
2600 MHz
Noise figure plot
Application Note AN180, Rev. 1.2
8 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Measurement Data
Table 3
Noise figure, tabular data
Frequency
NF
Noise temperature
2300 MHz
1.32 dB
102.7 K
2310 MHz
1.33 dB
104 K
2320 MHz
1.34 dB
104.6 K
2330 MHz
1.33 dB
103.7 K
2340 MHz
1.34 dB
104.8 K
2350 MHz
1.37 dB
107.4 K
2360 MHz
1.34 dB
104.8 K
2370 MHz
1.36 dB
106.4 K
2380 MHz
1.34 dB
104.7 K
2390 MHz
1.39 dB
109.2 K
2400 MHz
1.36 dB
106.9 K
2410 MHz
1.37 dB
107.8 K
2420 MHz
1.39 dB
109.1 K
2430 MHz
1.35 dB
106.1 K
2440 MHz
1.40 dB
110.2 K
2450 MHz
1.39 dB
108.9 K
2460 MHz
1.63 dB
132.3 K
2470 MHz
1.59 dB
127.9 K
2480 MHz
1.38 dB
108.4 K
2490 MHz
1.39 dB
109.5 K
2500 MHz
1.40 dB
110.4 K
2510 MHz
1.44 dB
114.2 K
2520 MHz
1.42 dB
112.1 K
2530 MHz
1.43 dB
113.4 K
2540 MHz
1.43 dB
112.7 K
2550 MHz
1.42 dB
112.3 K
2560 MHz
1.43 dB
113.1 K
2570 MHz
2580 MHz
1.44 dB
1.43 dB
114.5 K
113.1 K
2590 MHz
1.48 dB
117.3 K
2600 MHz
1.50 dB
120.1 K
Application Note AN180, Rev. 1.2
9 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Measurement Data
3.2
Amplifier Compression Point Measurement
ZVB20 Vector Network Analyzer is set up to sweep input power to LNA in a “Power Sweep” at a fixed frequency
of 2441 MHz. ZVB20 Port 1, which provides INPUT power to drive the LNA, has its power level calibrated
(“SOURCE POWER CAL”) with the NRP-Z21 power sensor to ensure power level accuracy with the reference
plane at the RF input connector of the amplifier. X-axis of VNA screen-shot below shows input power to LNA
swept from –25 dBm to –5 dBm.
Input 1 dB compression point = -13.6 dBm
Output 1 dB compression point = -13.6 dBm + (Gain – 1dB) = -13.6 dBm +8.5 dB = -5.1 dBm
Trc1 S21 dB Mag 1 dB / Ref 8 dB
Cal int PCal Smo
1
M 1 -24.98 dBm
• M 2 -13.58 dBm
S21
8.4685 dB
7.5270 dB
M19
M2
8
7
6
5
4
3
2
1
Ch1
Start -25 dBm
Freq 2.441 GHz
Stop -5 dBm
4/2/2009, 2:35 AM
Figure 4
Gain compression at 2441 MHz, VCC = +2.8 V, I = 5.0 mA, VCE = 2.5 V, T = 25 °C
Application Note AN180, Rev. 1.2
10 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Measurement Data
3.3
Amplifier Stability, Gain, Return Loss and Reverse Isolation Plots
3.3.1
Stability
Rohde and Schwarz ZVB Network Analyzer Calculates and plots stability factor “µ1” of the BFP540FESD
amplifier in real time. Stability Factor µ1 is defined as follows:
The necessary and sufficient condition for Unconditional Stability is µ1 > 1. In the plot, µ1 > 1 over 10 MHz to
12 GHz; amplifier is Unconditionally Stable over 10 MHz to 12 GHz frequency range.
Trc1 µ1 Lin Mag 500 mU/ Ref 1 U
Cal Smo
1
M 1 2.400000 GHz 1.7528 U
• M 2 2.441000 GHz 1.7715 U
M 3 2.483500 GHz 1.7868 U
µ1
5000
4500
4000
3500
3000
2500
M123
M
M
2000
1500
1000
Ch1
Start 50 MHz
Pwr -25 dBm
Stop 12 GHz
4/1/2009, 10:42 PM
Figure 5
Amplifier stability: Plot of Stability Factor µ1
Application Note AN180, Rev. 1.2
11 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Measurement Data
3.3.2
Input Return Loss
Reference plane is input SMA connector on PC board.
Trc1 S11 dB Mag 5 dB / Ref -20 dB
Cal Smo
1
M 1 2.400000 GHz -10.032 dB
• M 2 2.441000 GHz -10.280 dB
M 3 2.483500 GHz -10.495 dB
S11
10
5
0
-5
M
M
M123
-10
-15
-20
-25
-30
Ch1
Start 50 MHz
Pwr -25 dBm
Stop 12 GHz
4/1/2009, 10:38 PM
Figure 6
Input return loss / dB
Trc1 S11 Smith
Ref 1 U
Cal Smo
1
1
S11
M 1 2.400000 GHz
34.983
j23.312
1.546
2
• M 2 2.441000 GHz 35.791
j23.239
1.515
M 3 2.483500 GHz 36.410
j23.160
5
1.484
0.5
M
M
M12
3
0
0.2
0.5
1
2
Ω
Ω
nH
Ω
Ω
nH
Ω
Ω
nH
5
-5
-0.5
-2
-1
Ch1
Start 50 MHz
Pwr -25 dBm
Stop 12 GHz
4/1/2009, 10:39 PM
Figure 7
Input return loss (Smith chart)
Application Note AN180, Rev. 1.2
12 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Measurement Data
3.3.3
Forward Gain and Reverse Isolation
Trc1 S21 dB Mag 5 dB / Ref -20 dB
Cal Smo
M 1 2.400000 GHz 8.8642 dB
• M 2 2.441000 GHz 8.6961 dB
M 3 2.483500 GHz 8.5227 dB
S21
M
M
M123
10
1
5
0
-5
-10
-15
-20
-25
-30
Ch1
Start 50 MHz
Pwr -25 dBm
Stop 12 GHz
4/1/2009, 10:40 PM
Figure 8
Forward Gain / dB
Trc1 S12 dB Mag 5 dB / Ref -20 dB
Cal Smo
1
M 1 2.400000 GHz -23.930 dB
• M 2 2.441000 GHz -23.870 dB
M 3 2.483500 GHz -23.794 dB
S12
-15
-20
M
M123
M
-25
-30
-35
-40
-45
-50
-55
Ch1
Start 50 MHz
Pwr -25 dBm
Stop 12 GHz
4/1/2009, 10:40 PM
Figure 9
Reverse Isolation / dB
Application Note AN180, Rev. 1.2
13 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Measurement Data
3.3.4
Output Return Loss
Reference plane is output SMA connector on PC board.
Trc1 S22 dB Mag 5 dB / Ref 0 dB
Cal Smo
1
M 1 2.400000 GHz -10.202 dB
• M 2 2.441000 GHz -10.121 dB
M 3 2.483500 GHz -10.028 dB
S22
5
0
-5
M
M123
M
-10
-15
-20
-25
-30
-35
Ch1
Start 50 MHz
Pwr -25 dBm
Stop 12 GHz
4/1/2009, 10:41 PM
Figure 10
Output return loss / dB
Trc1 S22 Smith
Ref 1 U
Cal Smo
1
1
S22
M 1 2.400000 GHz
33.217
j20.820
1.381
2
• M 2 2.441000 GHz 34.203
j22.000
1.434
M 3 2.483500 GHz 35.466
j23.680
5
1.518
0.5
M123
M
M
0
0.2
0.5
1
2
Ω
Ω
nH
Ω
Ω
nH
Ω
Ω
nH
5
-5
-0.5
-2
-1
Ch1
Start 50 MHz
Pwr -25 dBm
Stop 12 GHz
4/1/2009, 10:41 PM
Figure 11
Output return loss (Smith chart)
Application Note AN180, Rev. 1.2
14 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Measurement Data
3.4
Amplifier Third Order Intercept (TOI) Measurement
In-band third order intercept point (IIP3) test:
Input Stimulus: f2 = 2440 MHz, f2 = 2442 MHz, -28 dBm each tone.
Input IP3 =-28 + (43.4/2) = -6.3dBm. Output IP3 = -6.3 dBm + 8.7 dB gain = +2.4 dBm
Figure 12
Output spectrum of LNA during test
Application Note AN180, Rev. 1.2
15 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Measurement Data
3.5
Amplifier Turn-On / Turn-Off Time Measurements
The amplifier is tested for turn-on / turn-off time. See diagram below. The RF signal generator runs continuously
at a power level sufficient to drive the output of the LNA to approximately 0 dBm when the LNA has DC power
ON.
Agilent DSO6104A
Digital Oscilloscope
+Vcc to amplifier
„Scope
Probe
+DC Pin
Amplifier
3 dB
Attenuator
Pad
RF Signal
Generator
Agilent
8473B
Detector
Ch. 1 (Trigger, edge)
1 Megaohm input Z
Ch. 2 ( 1 Megaohm or
50 ohm input Z)
! Note !
It may be necessary to set Ch. 2 Input Impedance to 50 ohms instead
of 1M ohm. 1M ohm setting may not allow detector to discharge
rapidly, depending on detector type and detector’s output capacitance,
and might give erroneous results to turn-off time measurement, e.g.
could indicate excessively long turn-off times. The user can test turnoff time with Ch. 2 input impedance set to 1M ohm and then 50 ohms
and see if the two results differ.
1. Signal Generator set such that output power of Amplifier is ~ 0 dBm when LNA is
powered ON
2. Channel 1 of oscilloscope monitors input power supply voltage to Amplifier (+1.8,
+2.8 or +3.0 volts ON, depending on the amplifier, and 0 volts when OFF). Hook
oscilloscope probe to +Vcc pin on amplifier to monitor Vcc rising / falling edge.
3. Channel 2 of oscilloscope monitors rectified RF output of Amplifier
4. To make measurement of turn-on time, leave DC power supply on, disconnect and
“ground” +Vcc line to discharge amplifier, then insert Vcc line back into power supply.
This method will eliminate turn on time transient of power supply itself. Set up trigger of
O‟Scope to trigger on rising edge of Ch.1
5. To make measurement of turn-off time, with supply ON, reset o‟scope, setup trigger
to trigger on falling edge of Ch. 1, and simply remove +Vcc line / wire from the power
supply input to turn amplifier OFF.
Figure 13
Turn-on / turn-off time: Test setup
Application Note AN180, Rev. 1.2
16 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Measurement Data
3.5.1
Turn On Time
Refer to oscilloscope screen-shot below. Upper trace (yellow, Channel 1) is the DC power supply turn-on step
waveform whereas the lower trace (green, Channel 2) is the rectified RF output signal of the LNA stage.
Amplifier turn-on time is aproximately 250 nanoseconds, or ~ 0.25 microseconds. Main source of time delay in
the LNA turn-on event are the R-C time constants formed by (R3 * C4), [ (R2 + R3) * C3 ], etc. Charge storage
has been minimized in this circuit so as to speed up turn on and turn off times. (Refer to Schematic diagram on
page 6). Note that the input impedance of the oscilloscope for Channel 2, which senses the rectified RF output
power of the amplifier, is set to 1 M for this picture.
Note: Both 50  and 1 M input impedances were tested for turn-on time and there was no appreciable
difference in results for turn-on time measurement.
Figure 14
Screen shot: Turn on time
Application Note AN180, Rev. 1.2
17 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Measurement Data
3.5.2
Turn-Off Time
Upper trace (Channel 1, yellow color) is the falling edge of the DC power supply voltage. Rectified RF output
signal (Channel 2, lower green trace) takes about ~ 66 nanoseconds, or 0.066 microseconds, to settle out after
power supply is disconnected.
Note: Input impedance of digital oscilloscope which senses RF detector diode output (Channel 2) is set to 50 
for this plot, as if a 1 M input impedance were used, the Schottky diode detector would have to
discharge through the large 1 M impedance, which would result in erroneously long turn-off times.
Figure 15
Screen shot: Turn on time
Application Note AN180, Rev. 1.2
18 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
Evaluation Board
4
Evaluation Board
PC board uses standard, low-cost FR4 glass-epoxy material. A cross-section diagram of the PC board is given
below.
PCB CROSS SECTION
0.012 inch / 0.305 mm
TOP LAYER
INTERNAL GROUND PLANE
0.028 inch / 0.711 mm ?
LAYER FOR MECHANICAL RIGIDITY OF PCB, THICKNESS HERE NOT CRITICAL AS
LONG AS TOTAL PCB THICKNESS DOES NOT EXCEED 0.045 INCH / 1.14 mm
(SPECIFICATION FOR TOTAL PCB THICKNESS: 0.040 + 0.005 / - 0.005 INCH;
1.016 + 0.127 mm / - 0.127 mm )
BOTTOM LAYER
Figure 16
PCB cross section
Figure 17
View of entire PC board
Figure 18
Close-in view of LNA section
Application Note AN180, Rev. 1.2
19 / 21
2011-05-31
BFP540FESD
BFP540FESD 2.4 GHz fast switching LNA
References
5
References
[1]
BFP540FESD Datasheet, Infineon Technologies AG
[2]
“ESD-Hardened Device Fuels UHF Amplifiers”. Microwaves & RF Magazine, July 2004. This article
discusses one technique for improving ESD robustness in silicon bipolar RF transistors. The article
describes the Infineon BFP460 device, however the basic concepts presented also apply to the
BFP540FESD, which, like the BFP460, also uses a “buffer layer” to achieve increased ESD-robustness.
[3]
“A High IIP3 Low Noise Amplifier for 1900 MHz Applications Using the SiGe BFP620 Transistor”.
Applied Microwaves and Wireless, July 2000.
Pages 2 – 4 discuss the use of Inductive Emitter Degeneration and additional charge storage
(capacitance) to stabilize and linearize LNA’s using Silicon Bipolar RF Transistors like the BFP620 or
BFP540FESD used in this Applications Note (AN180). Unlike the LNA shown in this reference, the LNA
used in this Applications Note (AN180) had to minimize use of charge storage in order to achieve fast
ON / OFF times. This resulted in compromising some Third-Order Intercept (TOI) performance.
Author
Gerard Wevers, Senior Staff Engineer of Business Unit “RF and Protection Devices”
Application Note AN180, Rev. 1.2
20 / 21
2011-05-31
w w w . i n f i n e o n . c o m
Published by Infineon Technologies AG
AN180