AN292 Wideband / Dual Band WLAN LNA using

BF R84 0L3 RH E SD
BFR840L3RHESD SiGe:C Ultra Low
Noise RF Transistor in Low Parts Count
Wideband / Dual Band 2.4 – 5.8 GHz
WLAN LNA Application
„0201‟ case size passives
< 1 microsecond Turn-On / Turn-Off Time
18.5 dB Gain, 1.1 dB Noise Figure at 2.4 GHz;
14.1 dB Gain, 1.4 dB Noise Figure at 5.8 GHz
(For 802.11a / ac / b / g / n Wireless LAN Applications)
Applic atio n N ote A N 292
Revision: Rev. 1.0
2012-08-14
RF and P r otecti on D evic es
Edition 2012-08-14
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2012 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
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Due to technical requirements, components may contain dangerous substances. For information on the types in
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persons may be endangered.
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Application Note AN292
Revision History: 2012-08-14
Previous Revision: No previous revision
Page
Subjects (major changes since last revision)
Trademarks of Infineon Technologies AG
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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. MIPI™ of MIPI Alliance, Inc. MIPS™ of MIPS
Technologies, Inc., USA. muRata™ of MURATA MANUFACTURING CO., MICROWAVE OFFICE™ (MWO) of
Applied Wave Research Inc., OmniVision™ of OmniVision Technologies, Inc. Openwave™ Openwave Systems
Inc. RED HAT™ Red Hat, Inc. RFMD™ RF Micro Devices, Inc. SIRIUS™ of Sirius Satellite 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 2011-11-11
Application Note AN292, Rev. 1.0
3 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
List of Content, Figures and Tables
Table of Contents
1
Introduction ........................................................................................................................................ 5
3
Schematic ........................................................................................................................................... 7
2
Measured Graphs ............................................................................................................................... 9
3
Evaluation Board and Layout Information .................................................................................... 27
4
Author ................................................................................................................................................ 29
5
Remark .............................................................................................................................................. 29
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
Figure 19
Figure 20
Figure 21
Figure 22
Figure 23
Block Diagram of low-cost WLAN application with Dual Band LNA .................................................... 6
Schematic Diagram .............................................................................................................................. 7
Noise Figure, 2.4 – 6 GHz Wideband / Dual Band LNA ..................................................................... 9
Noise Figure, Tabular Data ................................................................................................................ 10
Amplifier Gain compression at 2400 MHz .......................................................................................... 11
Amplifier Gain Compression at 5825 MHz ........................................................................................ 12
Amplifier stability factor “µ1” ............................................................................................................... 13
Input Match of Broadband / Dual Band LNA ..................................................................................... 14
Input Matching of the Broadband / Dual Band LNA, Smith Chart ...................................................... 15
Wideband Gain of Amplifier, DC Power ON ...................................................................................... 16
Wideband Gain of Amplifier, DC POWER OFF ................................................................................. 17
Reverse Isolation, DC power ON ....................................................................................................... 18
Reverse Isolation, DC Power OFF ..................................................................................................... 19
Amplifier Wideband Output Return Loss ............................................................................................ 20
Amplifier Output Return Loss, Smith Chart ........................................................................................ 21
rd
Amplifier Input 3 Order Intercept Point Measurement, 2400 MHz ................................................... 22
rd
Amplifier Input 3 Order Intercept Point Measurement, 5825 MHz ................................................... 23
Diagram of setup for making amplifier turn-on and turn-off times...................................................... 24
Oscilloscope screen shot, amplifier turn-on time ............................................................................... 25
Oscilloscope screen-shot, amplifier turn-off time ............................................................................... 26
View of Entire PC Board .................................................................................................................... 27
Close-In View of LNA Section. ......................................................................................................... 28
PC Board Cross-Section Information. ................................................................................................ 29
List of Tables
Table 1
Table 2
Summary of Measurement Results ...................................................................................................... 6
Bill-of-Materials..................................................................................................................................... 7
Application Note AN292, Rev. 1.0
4 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
1
Introduction
1.1
Device Overview: BFR840L3RHESD
Infineon Technologies‟ BFR840L3RHESD is a high gain, ultra low noise Silicon-GermaniumCarbon (SiGe:C) HBT device suitable for a wide range of Low Noise Amplifier (LNA)
applications. This RF Transistor has integrated protection structures to guard against Electro
Static Discharge (ESD) events up to 1.5kV per the Human Body Model (HBM), and these
same structures also protect the transistor against damage caused by excessive RF input
power levels up to +20 dBm. The device is housed in the RoHS-compliant, Halogen-free
TSLP-3-9 leadless package, which is only 1.0 x 0.6 x 0.31mm. The 0.31mm package height
makes this transistor a good choice for RF Module applications.
1.2
Circuitry
The circuit shown is targeted for Wireless LAN (WLAN) 802.11a / ac / b / g / n applications
where lowest possible cost, low external parts count, and high receiver sensitivity / long
range
are primary goals.
“0201” case size passives are used througout.
Resistive
Feedback is used to achieve unconditional stability and a good broadband 50 ohm match at
both input and output. Feedback also makes the amplifier more tolerant of component &
device variation, as well as making the design more forgiving of variations in PC board
layout. The price paid for using feedback is a slight increase in amplifier noise figure, as well
as some decrease in gain.
(The penalty paid in Noise Figure from the feedback is
approximately 0.4 dB at 2.4 GHz, and ~0.3 dB at 5 – 6 GHz). The LNA may be used as either
a single-band amplifier at 2.4 or at 5 – 6 GHz with no changes made to the element values,
or the LNA may be used in a dualband configuration where both WLAN bands are amplified
together in a single device, i.e. for legacy systems where Dual Band Dual Concurrent
operation is not required (refer to Figure 1). This simplification and commonality allows the
end user to use one LNA design across his or her different systems, at either WLAN
frequency band, simplifying logistics and reducing design effort. Potential applications may
include WLAN transceivers used in Access Points, laptop PCs, Tablets, Gaming Consoles,
USB dongles, etc. Generally, LNA‟s for these applications must be able to switch on & off
within about 1 microsecond or less. The charge storage (capacitance) used in this circuit is
Application Note AN292, Rev. 1.0
5 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
minimized to reduce on / off times, and this LNA achieves a switching time of ~ 15
nanoseconds. One potential trade-off for reduced capacitance values is a reduction in Third
Order Intercept (IP3) performance.
The good wideband match of the LNA – with an input
and output return loss of -10 dB or better across the entire 2.4 – 6 GHz frequency range makes integrating the amplifier with other system blocks (filters, switches, diplexers, etc.)
faster, easier and more predictable, reducing risk and time-to-market. No external emitter
degeneration is required. The LNA is unconditionally stable over the 50 MHz – 12 GHz
frequency range. External parts count (not including BFR840L3RHESD transistor) is 8; 4
capacitors, 3 resistors, and 1 chip inductors. All passives are „0201‟ case size. At 2.4 GHz,
the amplifier achieves ~ 18 dB gain with a Noise Figure of 1.1 dB, while at 5.8 GHz, the gain
is ~ 14 dB with a Noise Figure of 1.4 dB.
HPF
5 – 6 GHz Rx
Broadband
Antenna
WLAN
RF ASIC
Rx
Tx / Rx
Switch
2.4 GHz Rx
Dual Band
WLAN LNA
2.4 – 5.8 GHz
LPF
Low-Cost
LC Diplexer
Tx
Tx Path
Figure 1
Table 1
Block Diagram of low-cost WLAN application with Dual Band LNA
Summary of Measurement Results
Application Note AN292, Rev. 1.0
6 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
3
Schematic Diagram
V
All passives are "0201" case size
cc
= 3.0V
J3
DC Connector
Inductor L1 is MuRata LQP03T_02 Series
Total of 8 external elements:
4 x "C"
3 x "R"
1 x "L"
DC Operating Point @ T=25 C:
V CC = 3.0 V
I = 9.4 mA
V CE(Q1) = 1.87 V
I = 9.4 mA (nominal)
120 ohms
(0201)
R3
C4
33 pF
(0201)
R1
33K
(0201)
R2
1K
(0201)
C2
10 pF
(0201)
L1
6.2 nH
(0201)
J1
J2
50 ohm trace
RF INPUT
Q1
50 ohm trace
BFR840L3RHESD
RF Transistor
TSLP-3-9 Package
C1
10 pF
(0201)
C3
1.8 pF
(0201)
BFR840L3RHESD Wideband / Dual Band WLAN Feedback LNA
PCB = 840L3RHESD-120507 Rev A
PC Board Material = Standard FR4
Layer spacing (top RF to internal ground plane): 0.010 inch / 0.25 mm
Figure 2
Table 2
Symbol
Schematic Diagram
Bill-of-Materials
Value
Unit
Size
Manufacturer Comment
C1
10
pF
0201
Various
Input DC block
C2
10
pF
0201
Various
C3
1.8
pF
0201
Various
DC block for RF Feedback path
Output DC block; also influences input and
output matching
Application Note AN292, Rev. 1.0
7 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Table 2
Bill-of-Materials
Symbol
Value
Unit
Size
Manufacturer Comment
C4
33
pF
0201
Various
RF decoupling / lower frequency decoupling /
blocking cap. Strongest influence on Turn-On
/ Turn-Off time. Value was minimized to
speed up ON-OFF and OFF-ON time
L1
6.2
nH
0201
Murata
LQP03T series. RF choke at LNA output.
Influences output match
R1
33K
Ohm
0201
Various
DC biasing
R2
1K
Ohm
0201
Various
R3
120
Ohm
0201
Various
RF feedback resistor, output (collector) to
input (base). Provides wideband matching,
improves stability margin at price of reduced
gain and slightly degraded noise figure (~ 0.1
dB).
DC biasing. Drolps supply voltage below
transistor‟s safe limit (VCE); also provides
some DC negative feedback to stabilize DC
operating point of transistor over temperature,
hFE variation of transistor, etc.
Q1
---
---
TSLP-3-9
Infineon
1.0 x 0.6 x 0.31mm Technologies
J1, J2
---
---
---
J3
---
---
---
Application Note AN292, Rev. 1.0
Emerson –
Johnson
Tyco (AMP)
8 / 30
BFR840L3RHESD SiGe:C RF Transistor
RF edge Mount SMA Female Connector,
142-0701-841 (Input, Output RF Connectors)
5 Pin DC connector header, MTA-100 Series,
640456-5
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
2
Measured Graphs
Noise Figure Plot. From Rohde & Schwarz FS-K3 + FSEM30.
System preamplifier = MITEQ AFS3-00101200-22-10P-4-HS.
Noise Source = Agilent 346A
Figure 3
Noise Figure, 2.4 – 6 GHz Wideband / Dual Band LNA
Application Note AN292, Rev. 1.0
9 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Figure 4
Noise Figure, Tabular Data
Application Note AN292, Rev. 1.0
10 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Amplifier Compression Point Measurement, 2400 MHz
Gain Compression at 2400 MHz, VCC = +3.0 V, I = 9.4mA, VCE = 1.9V, T = 25C:
ZVB20 Vector Network Analyzer is set up to sweep input power to LNA in a “Power Sweep” at a
fixed frequency of 2400 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 –30 to –5 dBm.
Input P1dB = -15.6 dBm
Output P1dB = -15.6 dBm + (Gain-1dB) = -15.6 + 17.5 = +1.9 dBm
Trc1 S21 dB Mag 1 dB / Ref 18 dB
Cal int PCal Smo
1
M1 -29.64 dBm
• M2 -15.62 dBm
S21
20
18.600 dB
17.608 dB
M119
M2
18
17
16
15
14
13
12
Ch1 Base Pwr Start -30 dBm
Base Freq 2.4 GHz
Stop -10 dBm
7/18/2012, 4:37 AM
Figure 5
Amplifier Gain compression at 2400 MHz
Application Note AN292, Rev. 1.0
11 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Amplifier Compression Point Measurement, 5825 MHz
Gain Compression at 5825 MHz, VCC = +3.0 V, I = 9.4mA, VCE = 1.9V, T = 25C:
Input P1dB = -12.6 dBm
Output P1dB = -12.6 dBm + (Gain-1dB) = -12.6 + 13.1 = +0.5 dBm*
*(Used small signal gain from S21 plot on page 16, 14.1 dB gain )
Trc1 S21 dB Mag 1 dB / Ref 14 dB
Cal int PCal Smo
1
M1 -29.64 dBm
• M2 -12.56 dBm
S21
16
14.022 dB
13.021 dB
15
M1
14
M2
13
12
11
10
9
8
Ch1 Base Pwr Start -30 dBm
Base Freq 5.825 GHz
Stop -10 dBm
7/18/2012, 4:40 AM
Figure 6
Amplifier Gain Compression at 5825 MHz
Application Note AN292, Rev. 1.0
12 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Rohde and Schwarz ZVB Network Analyzer Calculates and plots stability factor “1” of the
BFR840L3RHESD Wideband LNA in real time. Stability Factor

1
1 is defined as follows [1]:
1 - |S11|2
=
| S22 – S11* det(S) | + |S21S12|
The necessary & sufficient condition for Unconditional Stability is 1 > 1.0. In the plot, 1 >
1.0 over 10 MHz – 12 GHz; amplifier is Unconditionally Stable over 50 MHz – 12 GHz frequency
range.
Trc1 µ1 Lin Mag 100 mU/ Ref 1 U
Cal Smo
1
M1
M2
M3
M4
• M5
µ1
1600
1500
2.400000
2.483500
4.900000
5.825000
1.405000
GHz
GHz
GHz
GHz
GHz
1.0437
1.0504
1.2391
1.2834
1.0107
U
U
U
U
U
1400
M4
1300
M3
1200
1100
M5
M2
M1
1000
900
800
Ch1 Base Freq Start 50 MHz
Base Pwr -25 dBm
Stop 12 GHz
7/18/2012, 1:28 AM
Figure 7
Amplifier stability factor “µ1”
Application Note AN292, Rev. 1.0
13 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Note excellent input match of amplifier over entire 2.4 – 6 GHz frequency range.
Trc1 S11 dB Mag 5 dB / Ref 0 dB
Cal Smo
1
M1
M2
M3
• M4
S11
15
2.400000
2.483500
4.900000
5.825000
GHz
GHz
GHz
GHz
-12.832
-12.732
-11.898
-13.049
dB
dB
dB
dB
10
5
0
-5
-10
M2
M1
M3
M4
-15
-20
-25
Ch1 Base Freq Start 50 MHz
Base Pwr -25 dBm
Stop 12 GHz
7/18/2012, 1:22 AM
Figure 8
Input Match of Broadband / Dual Band LNA
Application Note AN292, Rev. 1.0
14 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Reference Plane = SMA RF Input Connector to PC Board.
Trc1 S11 Smith
Ref 1 U
Cal Smo
1
1
S11
M1 2.400000 GHz
0.5
M2
M1
0
0.2
0.5
1
M3
2
33.535
j9.8169
651.00
2
M2 2.483500 GHz 33.916
j11.033
707.05
M3 4.900000 GHz 82.511
5
-j9.0865
3.575
• M4 5.825000 GHz 53.911
-j23.409
5
1.167
Ω
Ω
pH
Ω
Ω
pH
Ω
Ω
pF
Ω
Ω
pF
M4
-5
-0.5
-2
-1
Ch1 Base Freq Start 50 MHz
Base Pwr -25 dBm
Stop 12 GHz
7/18/2012, 1:22 AM
Figure 9
Input Matching of the Broadband / Dual Band LNA, Smith Chart
Application Note AN292, Rev. 1.0
15 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Trc1 S21 dB Mag 5 dB / Ref 0 dB
Cal Smo
M1
M2
M3
• M4
S21
25
M1
M2
20
1
M3
2.400000
2.483500
4.900000
5.825000
GHz
GHz
GHz
GHz
18.536
18.375
14.991
14.053
dB
dB
dB
dB
M4
15
10
5
0
-5
-10
-15
Ch1 Base Freq Start 50 MHz
Base Pwr -25 dBm
Stop 12 GHz
7/18/2012, 1:23 AM
Figure 10
Wideband Gain of Amplifier, DC Power ON
Application Note AN292, Rev. 1.0
16 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Note: Gain change, ON to OFF, is ~ -38 dB at 2.4 GHz, and ~ -34 dB at 5.8 GHz
Trc1 S21 dB Mag 5 dB / Ref 0 dB
Cal Smo
1
M1
M2
M3
• M4
S21
10
2.400000
2.483500
4.900000
5.825000
GHz
GHz
GHz
GHz
-19.156
-19.180
-19.171
-20.121
dB
dB
dB
dB
5
0
-5
-10
-15
M1
M2
M3
M4
-20
-25
-30
Ch1 Base Freq Start 50 MHz
Base Pwr -25 dBm
Stop 12 GHz
7/18/2012, 1:24 AM
Figure 11
Wideband Gain of Amplifier, DC POWER OFF
Application Note AN292, Rev. 1.0
17 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Trc1 S12 dB Mag 5 dB / Ref 0 dB
Cal Smo
1
M1
M2
M3
• M4
S12
5
2.400000
2.483500
4.900000
5.825000
GHz
GHz
GHz
GHz
-24.096
-24.068
-22.337
-21.447
dB
dB
dB
dB
0
-5
-10
-15
M3
-20
M4
M1
M2
-25
-30
-35
Ch1 Base Freq Start 50 MHz
Base Pwr -25 dBm
Stop 12 GHz
7/18/2012, 1:24 AM
Figure 12
Reverse Isolation, DC power ON
Application Note AN292, Rev. 1.0
18 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Trc1 S12 dB Mag 5 dB / Ref 0 dB
Cal Smo
1
M1
M2
M3
• M4
S12
5
2.400000
2.483500
4.900000
5.825000
GHz
GHz
GHz
GHz
-19.057
-19.086
-19.010
-19.958
dB
dB
dB
dB
0
-5
-10
-15
M1
M2
M3
M4
-20
-25
-30
-35
Ch1 Base Freq Start 50 MHz
Base Pwr -25 dBm
Stop 12 GHz
7/18/2012, 1:25 AM
Figure 13
Reverse Isolation, DC Power OFF
Application Note AN292, Rev. 1.0
19 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Note excellent output match of amplifier over entire 2.4 – 6 GHz frequency range. This
eases integration with other receiver chain blocks (i.e. filters, switches, etc.)
Trc1 S22 dB Mag 5 dB / Ref 0 dB
Cal Smo
1
M1
M2
M3
• M4
S22
10
2.400000
2.483500
4.900000
5.825000
GHz
GHz
GHz
GHz
-11.068
-10.954
-12.468
-12.738
dB
dB
dB
dB
5
0
-5
M2
M1
-10
M3
M4
-15
-20
-25
-30
Ch1 Base Freq Start 50 MHz
Base Pwr -25 dBm
Stop 12 GHz
7/18/2012, 1:26 AM
Figure 14
Amplifier Wideband Output Return Loss
Application Note AN292, Rev. 1.0
20 / 30
2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Reference Plane = SMA RF Output Connector to PC Board.
Trc1 S22 Smith
Ref 1 U
Cal Smo
1
1
S22
M1 2.400000 GHz
0.5
M2
M1
M4
0
0.2
0.5
1
2
33.495
j17.116
1.135
2
M2 2.483500 GHz 35.042
j19.804
1.269
M3 4.900000 GHz 34.234
5
-j12.823
2.533
• M4 5.825000 GHz 35.373
j13.686
5
373.95
Ω
Ω
nH
Ω
Ω
nH
Ω
Ω
pF
Ω
Ω
pH
M3
-5
-0.5
-2
-1
Ch1 Base Freq Start 50 MHz
Base Pwr -25 dBm
Stop 12 GHz
7/18/2012, 1:26 AM
Figure 15
Amplifier Output Return Loss, Smith Chart
Application Note AN292, Rev. 1.0
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2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
In-Band Third Order Intercept (IIP3) Test, 2400 MHz:
Input Stimulus: f1=2400 MHz, f2=2401 MHz, -28 dBm each tone
Input IP3 = -28+(45.0 / 2) = - 5.5 dBm
Output IP3 = - 5.5 dBm + 18.5 dB gain = +13.0 dBm
Figure 16
rd
Amplifier Input 3 Order Intercept Point Measurement, 2400 MHz
Application Note AN292, Rev. 1.0
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2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Input Third Order Intercept (IIP3) Test, 5825 MHz:
Input Stimulus: f1=5824 MHz, f2=5825 MHz, -28 dBm each tone
Input IP3 = -28+(56.6 / 2) = +0.3 dBm
Output IP3 = +0.3 dBm + 14.1 dB gain = +14.4 dBm
Figure 17
rd
Amplifier Input 3 Order Intercept Point Measurement, 5825 MHz
Application Note AN292, Rev. 1.0
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2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Block Diagram, Test Setup for Amplifier Turn-On / Turn Off time measurement
Figure 18
Diagram of Setup for Making Amplifier Turn-On and Turn-Off Times.
Application Note AN292, Rev. 1.0
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2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Amplifier 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 15 nanoseconds, or ~ 0.015
microseconds. Main source of time delay in the LNA turn-on event are the R-C time constants
formed by (R3 * C4), 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 X).
Figure 19
Oscilloscope Screen Shot, Amplifier Turn-On Time
Application Note AN292, Rev. 1.0
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2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Amplifier 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 ~ 15 nanoseconds, or 0.015
microseconds, to settle out after power supply is turned off.
Figure 20
Oscilloscope Screen-Shot, Amplifier Turn-Off Time
Application Note AN292, Rev. 1.0
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BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
3
Evaluation Board and Layout Information
Figure 21
View of Entire PC Board
Application Note AN292, Rev. 1.0
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2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Note – five (5) 0.2mm diameter ground via holes are used for grounding (emitter
connection) near top right corner of Q1. R2 is the feedback resisistor (RF Feedback).
Figure 22
Close-In View of BFR840L3RHESD Wideband / Dualband LNA.
Application Note AN292, Rev. 1.0
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2012-08-14
BFR840L3RHESD
BFR840L3RHESD 2.4 - 5.8 GHz Dualband WLAN LNA
Note – standard low-cost “FR4” PC board material is used.
PCB CROSS SECTION
TOP LAYER (RF TRACES)
0.010 inch / 0.254 mm
INTERNAL GROUND PLANE
0.031 inch / 0.787 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 23
PC Board Cross-Section Information.
4
Author
Gerard Wevers,Senior Staff Applications Engineer of Business Unit “RF and Protection
Devices”.
5
Remark
The data graphs are exported from the Rohde and Schwarz ZVB network analyzer, FS-K3
Noise Figure Measurement system, or Agilent DSO6104A Oscilloscope.
Application Note AN292, Rev. 1.0
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2012-08-14
w w w . i n f i n e o n . c o m
Published by Infineon Technologies AG
AN292