AN168

Application Note, Rev. 1.2, November 2008
Application Note No. 168
BFP740F SiGe:C Ultra Low Noise RF Transistor in
5 – 6 GHz LNA Application with 16 dB Gain, 1.3 dB
Noise Figure & 1 microsecond Turn-On / Turn-Off Time
(For 802.11a & 802.11n “MIMO” Wireless LAN Applications)
Small Signal Discretes
Never stop thinking
Edition 2008-11-14
Published by
Infineon Technologies AG
81726 München, Germany
© Infineon Technologies AG 2008.
All Rights Reserved.
LEGAL DISCLAIMER
THE INFORMATION GIVEN IN THIS APPLICATION NOTE IS GIVEN AS A HINT FOR THE
IMPLEMENTATION OF THE INFINEON TECHNOLOGIES COMPONENT ONLY AND SHALL
NOT BE REGARDED AS ANY DESCRIPTION OR WARRANTY OF A CERTAIN
FUNCTIONALITY, CONDITION OR QUALITY OF THE INFINEON TECHNOLOGIES
COMPONENT. THE RECIPIENT OF THIS APPLICATION NOTE MUST VERIFY ANY
FUNCTION DESCRIBED HEREIN IN THE REAL APPLICATION. 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) WITH RESPECT TO ANY AND
ALL INFORMATION GIVEN IN THIS APPLICATION NOTE.
Information
For further information on technology, delivery terms and conditions and prices please contact
your 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 your nearest Infineon Technologies Office.
Infineon Technologies Components may only be used in life-support devices or systems 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
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If they fail, it is reasonable to assume that the health of the user or other persons may be
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Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
Application Note No. 168
Revision History: 2008-11-07, Rev 1.0
2008-11-11, Rev 1.1
2008-11-14, Rev 1.2
Previous Version:
Page
Subjects (major changes since last revision)
Cover
Title change
3
Addition of weblinks
4
6
7
13 – 20
Update of summary values
Updated Schematic (element values C1, C5, L1, L3)
Updated Bill Of Material (values of C1, C5, L1, L3)
Updated network analyzer plots
Trademarks
SIEGET® is a registered trademark of Infineon Technologies AG.
Additional Information:
More details about Infineon RF Transistors may be found at www.infineon.com/RF
Direct link to RF Transistor Datasheets / Specifications: www.infineon.com/rf.specs
For S-Parameters, Noise Parameters, SPICE models: www.infineon.com/rf.models
For Application Notes: www.infineon.com/rf.appnotes
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
1
BFP740F SiGe:C Ultra Low Noise RF Transistor in 5 – 6 GHz LNA
Application with 16 dB Gain, 1.3 dB Noise Figure & 1 microsecond TurnOn / Turn-Off Time
Overview
• Infineon Technologies BFP740F is a high gain, ultra low noise Silicon-Germanium-Carbon
(SiGe:C) HBT device suitable for a wide range of Low Noise Amplifier (LNA) applications.
2
•
The circuit implementation shown in this document is targeted for 802.11a & 802.11n “MIMO”
applications in the Wireless Local Area Network (WLAN) market, particularly for Access Points
(AP’s) which require external LNA’s to fulfill high-sensitivity / long range requirements. LNA’s
for this application must be able to switch on / off within about 1 microsecond. The charge
storage (capacitance) used in the circuit is minimized to reduce turn-on / turn-off times. Tradeoff for reduced capacitance values is a reduction in Third Order Intercept (IP3) performance.
Amplifier is Unconditionally Stable (µ1 > 1.0) from 10 MHz – 12 GHz.
•
External parts count (not including BFP740F transistor) = 12; 6 capacitors, 3 resistors, and 3
chip inductors. All passives are ‘0402’ case size. BFP740F transistor package is RoHS –
compliant and measures 1.4 x 1.2 x 0.55mm.
Summary Of Performance Data
(T=25 °C, network analyzer source power ≈ -25 dBm, VCC = 3.0 V, VCE = 2.1 V, IC=14.8 mA, ZS=ZL=50 Ω )
Frequency
* NF ** IIP3 ** OIP3 IP1dB OP1dB
MHz
dB[s11]2 dB[s21]2 dB[s12]2 dB[s22]2 dB dBm
dBm dBm dBm
- 10.9
-24.7
-9.2
--------5150
16.4
1.3
-12.7
-24.1
-10.3
+0.6
+22.1 -7.3
+7.8
5470
16.4
1.3
-10.9
-23.9
-14.3
--------5825
16.0
1.3
--------------2500
4.0
--* does not extract PCB loss. If PCB loss (at input) were extracted, noise figure would be ~ 0.2 dB lower.
Note: reverse isolation ( dB[s12]2 ) when DC power to LNA is OFF = -13.7 dB @ 5470 MHz.
3
Details of PC Board Construction
PC board is fabricated from 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
Application Note
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Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
4
TSFP-4 Package Outline and Footprint
(Dimensions in millimeters). Note maximum package height is 0.59 mm / 0.023 inch.
Recommended Soldering Footprint for TSFP-4 (dimensions in millimeters). Device package is to be
oriented as shown in above drawing (e.g. orient long package dimension horizontally on this footprint).
Application Note
5 / 24
Rev. 1.2, 2008-11-14
Application Note
6 / 24
C1
0.3pF
RF
INPUT
C3
1.5pF
C2
1.2pF
L1
6.8nH
R2
36K
L2
R1
22 ohms
R3
39 ohms
C5
1.2pF
C6
0.3pF
cc
J2
RF OUTPUT
= 3.0 V
= 50 ohm microstripline
L3
1.2nH
C4
33pF
I = 14.8 mA
Q1: VCE = 2.1 V
Q1
1.5nH
BFP740F
SiGe
Transistor
PCB = 740F-080919 Rev A
PC Board Material = Standard FR4
J1
6 capacitors
3 inductors
3 resistors
12 external passives used:
V
5
Inductors are Murata LQP15M Series (formerly LQP10A)
0402 case size. Capacitors and resistors are 0402 case size.
J3
DC Connector
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
Schematic Diagram
Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
6
Bill Of Material (BOM)
Reference
Designator
Value
C1
0.3pF
C2
C3
C4
C5
1.2pF
1.5pF
33pF
1.2pF
C6
0.3pF
L1
6.8nH
L2
Description / Part #
Manufacturer
0.3pF, 50V, COG ‘0402’ case size
capacitor
Murata GRM1555C1HR30BZ01D or
equivalent
‘0402’ chip capacitor
‘0402’ chip capacitor
‘0402’ chip capacitor
‘0402’ chip capacitor
0.3pF, 50V, COG ‘0402’ case size
capacitor
Murata GRM1555C1HR30BZ01D or
equivalent
Function
Murata, AVX,
etc.
Input Match
Various
Various
Various
Various
Murata, AVX,
etc.
Input DC block, Input Matching
RF decoupling / blocking cap
RF decoupling / blocking cap
RF decoupling / blocking cap
Output DC block and output
matching.
Also influences
input match.
6.8nH ‘0402’ case size chip inductor
Murata LQP15M Series or equivalent
Murata
1.5nH
1.5nH ‘0402’ case size chip inductor
Murata LQP15M series or equivalent
Murata
L3
1.2nH
1.2nH ‘0402’ case size chip inductor
Murata LQP15M series or equivalent
Murata
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.
Output
matching;
also
influences input match.
R1
R2
R3
22Ω
36KΩ
39Ω
‘0402’ chip resistor
‘0402’ chip resistor
‘0402’ chip resistor
Various
Various
Various
Q1
---
J1, J2
J3
---
Application Note
BFP740F SiGe:C Low Noise RF
Transistor, TSFP-4 package
Infineon
Technologies
RF Edge Mount SMA Female Connector,
142-0701-841
MTA-100 Series 5 pin connector
640456-5
PC Board, Part # 740F-080919 Rev A
7 / 24
For RF stability improvement.
DC biasing (base).
DC biasing (provides DC
negative feedback to stabilize
DC operating point over
temperature
variation,
transistor hFE variation, etc.)
LNA active device.
Emerson /
Johnson
Tyco (AMP)
Input, Output RF connector
Infineon
Technologies
Printed Circuit Board
5 Pin DC connector header
Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
7
Scanned Images of PC Board
View of Entire PC Board
Application Note
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Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
Close-In View of LNA Section
Application Note
9 / 24
Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
8
Noise Figure Measurement Data
Noise Figure Plot, from Rohde and Schwarz FSEK3 + FSEM30
Rohde & Schwarz FSEK3
05 Nov 2008
Noise Figure Measurement
EUT Name:
Manufacturer:
Operating Conditions:
Operator Name:
Test Specification:
Comment:
BFP740F 5 - 6 GHz LNA, Fast Switching / Fast Turn ON-OFF Time
Infineon Technologies
T=25 C, V = 3.0V, Vce = 2.1V, I = 14.9mA
Gerard Wevers
WLAN 802.11n, 802.11n
PCB = 740F-080919 Rev A; Preamp = MITEQ AFS3-04000800-10-ULN
5 November 2008
Analyzer
RF Att:
Ref Lvl:
0.00 dB
-45.00 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
2.00
1.90
1.80
1.70
1.60
1.50
1.40
1.30
1.20
1.10
1.00
4800 MHz
Application Note
120 MHz / DIV
10/ 24
6000 MHz
Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
Noise Figure, Tabular Data
Taken With Rohde & Schwarz FSEM30 + FSEK3
System Preamplifier = MITEQ 4 – 8 GHz LNA
Frequency
4800 MHz
4850 MHz
4900 MHz
4950 MHz
5000 MHz
5050 MHz
5100 MHz
5150 MHz
5200 MHz
5250 MHz
5300 MHz
5350 MHz
5400 MHz
5450 MHz
5500 MHz
5550 MHz
5600 MHz
5650 MHz
5700 MHz
5750 MHz
5800 MHz
5850 MHz
5900 MHz
5950 MHz
6000 MHz
Application Note
Nf
1.31 dB
1.31 dB
1.32 dB
1.31 dB
1.31 dB
1.30 dB
1.26 dB
1.30 dB
1.29 dB
1.28 dB
1.24 dB
1.25 dB
1.26 dB
1.24 dB
1.27 dB
1.26 dB
1.28 dB
1.23 dB
1.26 dB
1.27 dB
1.29 dB
1.28 dB
1.29 dB
1.26 dB
1.29 dB
11/ 24
Temp
102.5 K
102 K
102.8 K
101.7 K
101.7 K
101.2 K
97.8 K
101 K
100.6 K
99.4 K
96.2 K
96.5 K
97.7 K
95.9 K
98.7 K
98 K
99.6 K
94.6 K
97.7 K
98.9 K
100.3 K
99.8 K
100.2 K
97.2 K
100.1 K
Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
9
Amplifier Compression Point Measurement
Gain Compression at 5470 MHz, VCC = +3.0 V, I = 14.8mA, VCE = 2.1V, T = 25°C:
Rohde & Schwarz ZVB20 Vector Network Analyzer is set up to sweep input power to LNA at a
fixed frequency of 5470 MHz. X-axis of VNA screen-shot below shows input power to LNA being
swept from –30 to –5 dBm. ZVB20 output power is checked / verified against HP E4419A power
meter; ZVB20 output power is ≅ 0.6 dB lower than indicated on ZVB20 due to test cable loss.
Therefore, a 0.6 dB offset is needed.
Input 1 dB compression point = - 6.7 dBm – 0.6 dB offset = - 7.3 dBm
Output 1dB compression point = - 7.3 dBm + (Gain – 1dB) = -7.3dBm + 15.1 dB = +7.8 dBm
Trc1 S21 dB Mag 0.5 dB / Ref 16 dB
Cal
1
M 1 -24.56 dBm
• M 2 -6.66 dBm
S21
16.5
16.081 dB
15.060 dB
M1
16.0
15.5
M2
15.0
14.5
14.0
13.5
13.0
12.5
Ch1
Start -30 dBm
Freq 5.47 GHz
Stop -5 dBm
11/7/2008,9:37 AM
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Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
10
Amplifier Stability, Gain, Return Loss and Reverse Isolation Plots
Amplifier Stability - Plot of Stability Factor “
µ”:
1
Rohde and Schwarz ZVB Network Analyzer Calculates and plots stability factor “µ1” of the BFP740F
amplifier in real time. Stability Factor µ1 is defined as follows [1]:
µ
1 - |S11|2
1
=
| S22 – S11* det(S) | + |S21S12|
The necessary and sufficient condition for Unconditional Stability is µ1 > 1.0. In the plot, µ1 > 1.0
over 10 MHz – 12 GHz; amplifier is Unconditionally Stable over 10 MHz – 12 GHz frequency range.
Trc1
µ1 Lin Mag 100 mU/ Ref 1 U
Mem2[Trc1] S11 Lin Mag 100 mU/ Ref 1 U
Cal Offs
Invisible
1
M1
M2
M3
•M 4
µ1
1800
5.150000
5.470000
5.825000
2.483500
GHz
GHz
GHz
GHz
1.1310
1.2012
1.3297
1.0329
U
U
U
U
1700
1600
1500
1400
M3
1300
M2
1200
M1
1100
M4
1000
Ch1
Start 10 MHz
Pwr -25 dBm
Stop 12 GHz
11/14/2008,9:44 AM
[1]. “Fundamentals of Vector Network Analysis”, Michael Hiebel, 4th edition 2008, pages 175 – 177, ISBN
978-3-939837-06-0
Application Note
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Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
Input Return Loss, Log Mag
10 MHz – 12 GHz Sweep
Trc1
S11 dB Mag 3 dB / Ref 0 dB
Mem2[Trc1] S11 dB Mag 3 dB / Ref 0 dB
Cal Offs
Invisible
1
M1
M2
M3
•M 4
S11
6
5.150000
5.470000
5.825000
2.483500
GHz
GHz
GHz
GHz
-10.894
-12.714
-10.972
-1.9309
dB
dB
dB
dB
3
0
M4
-3
-6
-9
M1 M3
M2
-12
-15
-18
Ch1
Start 10 MHz
Pwr -25 dBm
Stop 12 GHz
11/14/2008,9:39 AM
Application Note
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Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
Input Return Loss, Smith Chart
Reference Plane = Input SMA Connector on PC Board
10 MHz – 12 GHz Sweep
Trc1
S11 Smith
Mem2[Trc1] S11 Smith
Ref 1 U
Ref 1 U
Cal Offs
Invisible
1
1
S11
0.5
M1
M2
0
0.2
0.5
57.680
j31.168
963.20
2
M 2 5.470000 GHz 77.030
j12.049
350.58
M 3 5.825000 GHz 69.318
5
-j28.953
943.68
• M 4 2.483500 GHz 6.4220
-j20.059
3.195
2
5
M 1 5.150000 GHz
1
Ω
Ω
pH
Ω
Ω
pH
Ω
Ω
fF
Ω
Ω
pF
M3
-5
M4
-0.5
-2
-1
Ch1
Start 10 MHz
Pwr -25 dBm
Stop 12 GHz
11/14/2008,9:40 AM
Application Note
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Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
Forward Gain. Input / Output Matching Circuits of LNA reduce gain in 2.4 – 2.5 GHz band.
10 MHz – 12 GHz Sweep
Trc1
S21 dB Mag 5 dB / Ref 0 dB
Mem2[Trc1] S11 dB Mag 5 dB / Ref 0 dB
Cal Offs
Invisible
M 1M 2M 3
S21
15
1
M1
M2
M3
•M 4
5.150000
5.470000
5.825000
2.483500
GHz
GHz
GHz
GHz
16.421
16.363
15.986
4.0479
dB
dB
dB
dB
10
M4
5
0
-5
-10
-15
-20
-25
Ch1
Start 10 MHz
Pwr -25 dBm
Stop 12 GHz
11/14/2008,9:41 AM
Application Note
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Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
Reverse Isolation
10 MHz – 12 GHz Sweep
Trc1
S12 dB Mag 10 dB / Ref 0 dB
Mem2[Trc1] S11 dB Mag 10 dB / Ref 0 dB
Cal Offs
Invisible
1
M1
M2
M3
•M 4
S12
10
5.150000
5.470000
5.825000
2.483500
GHz
GHz
GHz
GHz
-24.660
-24.123
-23.861
-44.652
dB
dB
dB
dB
0
-10
M 1M 2M 3
-20
-30
M4
-40
-50
-60
-70
Ch1
Start 10 MHz
Pwr -25 dBm
Stop 12 GHz
11/14/2008,9:41 AM
Application Note
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Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
Reverse Isolation, AMPLIFIER DC POWER TURNED OFF.
10 MHz – 12 GHz Sweep
Trc1
S12 dB Mag 10 dB / Ref 0 dB
Mem2[Trc1] S11 dB Mag 10 dB / Ref 0 dB
Cal Offs
Invisible
1
M1
M2
M3
•M 4
S12
10
5.150000
5.470000
5.825000
2.483500
GHz
GHz
GHz
GHz
-14.601
-13.723
-12.140
-33.160
dB
dB
dB
dB
0
M3
M 1M 2
-10
-20
M4
-30
-40
-50
-60
-70
Ch1
Start 10 MHz
Pwr -25 dBm
Stop 12 GHz
11/14/2008,9:42 AM
Application Note
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Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
Output Return Loss, Log Mag
10 MHz to 12 GHz Sweep
Trc1
S22 dB Mag 5 dB / Ref 0 dB
Mem2[Trc1] S11 dB Mag 5 dB / Ref 0 dB
Cal Offs
Invisible
1
M1
M2
M3
•M 4
S22
10
5.150000
5.470000
5.825000
2.483500
GHz
GHz
GHz
GHz
-9.2165
-10.323
-14.328
-0.6761
dB
dB
dB
dB
5
M4
0
-5
M1
M2
-10
M3
-15
-20
-25
-30
Ch1
Start 10 MHz
Pwr -25 dBm
Stop 12 GHz
11/14/2008,9:42 AM
Application Note
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Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
Output Return Loss, Smith Chart
Reference Plane = Output SMA Connector on PC Board
10 MHz to 12 GHz Sweep
Trc1
S22 Smith
Mem2[Trc1] S11 Smith
Ref 1 U
Ref 1 U
Cal Offs
Invisible
1
1
S22
102.72
-j3.7954
8.142
2
M 2 5.470000 GHz 73.382
-j30.880
942.21
M 3 5.825000 GHz 45.753
5
-j18.203
1.501
• M 4 2.483500 GHz 1.9190
j1.1342
M 12
72.682
5
M 1 5.150000 GHz
0.5
M4
0
0.2
0.5
1
M3
Ω
Ω
pF
Ω
Ω
fF
Ω
Ω
pF
Ω
Ω
pH
M2
-5
-0.5
-2
-1
Ch1
Start 10 MHz
Pwr -25 dBm
Stop 12 GHz
11/14/2008,9:43 AM
Application Note
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Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
11
Amplifier Third Order Intercept (TOI) Measurement
In-Band Third Order Intercept (IIP3) Test.
Input Stimulus: f1=5470 MHz, f2=5471 MHz, -23 dBm each tone.
Input IP3 = -23 + (47.2 / 2) = +0.6 dBm.
Application Note
Output IP3 = +0.6 dBm + 16.1 dB gain = +22.1 dBm.
21/ 24
Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
12
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
+3 Volts
Ch. 1 (Trigger, edge)
BFP740F
Low Noise
Amplifier
Ch. 2
10 dB
Attenuator
Pad
Agilent
8473B
Detector
Signal
Generator
f=5470 MHz
1. Signal Generator set such that output power of BFP740F LNA is approx. 0
dBm when LNA is powered ON
2. Channel 1 of oscilloscope monitors input power supply voltage to
BFP740F LNA (+3.0 volts when ON, ~ 0 volts when OFF)
3. Channel 2 of oscilloscope monitors rectified RF output of BFP740F LNA
4. To make measurement of turn-on time, turn power supply OFF, reset
o’scope, setup trigger to trigger on rising edge of Ch.1
5. To make measurement of turn-off time, turn power supply ON, reset
o’scope, setup trigger to trigger on falling edge of Ch. 1
Application Note
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Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
a) Turn On Time:
Refer to oscilloscope screen-shot below. Upper trace (yellow, Channel 1) is the DC power supply turnon 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 880 nanoseconds, or 0.9 microseconds.
Main source of time delay in the LNA turn-on and turn-off events 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 3).
Application Note
23/ 24
Rev. 1.2, 2008-11-14
Application Note No. 168
BFP740F 5 – 6 GHz LNA with 1µSec Turn-On / Turn-Off Time
b) Turn-Off Time:
Rectified RF output signal (lower green trace) takes about ~ 1 microsecond to settle out after power
supply is turned off.
Application Note
24/ 24
Rev. 1.2, 2008-11-14
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