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 0
T h e S i G e B F P 6 4 0 a s a 2 .4 G H z L o w N o i s e
Amplifier (LNA)
R F & P r o t e c ti o n D e v i c e s
Edition 2007-11-07
Published by
Infineon Technologies AG
81726 München, Germany
© Infineon Technologies AG 2009.
All Rights Reserved.
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Application Note No. 130
Application Note No. 130
Revision History: 2007-11-07, Rev. 1.2
Previous Version: 2005-08-19, Rev. 1.1
Page
Subjects (major changes since last revision)
All
Small changes in figure descriptions
Application Note
3
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
1
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Overview
The new BFP640 SiGe Transistor is shown in a 2400 - 2483.5 MHz Low Noise Amplifier Application. The BFP640
is a newer sibling of the BFP620, offering higher gain and higher breakdown voltage than BFP620.Potential target
markets at 2.4 GHz include:
•
•
•
•
•
BlueTooth
HomeRF
802.11b
Cordless
Other 2.4 GHz ISM band applications
Features of the Low Noise Amplifier (LNA)
•
•
•
•
•
•
•
Low parts count: 11 passive external elements
Excellent Noise Figure: 1.1 dB
Good Gain: 15 dB
Low power consumption: 5.3 mA at 3.3 V
Outstanding Linearity: IIP3 of +15.3 dBm
Unconditional Stability
Low Cost
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SOT-343 Package
PCB Cross - Section Diagram
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PCB - Cross Sectional Diagram
Application Note
4
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
BFP640 differs from its older sibling, the BFP620, as follows
Table 1
Differences between BFP640 and BFP620
Parameter
BFP620
BFP640
Comments
BVCEO
2.3 V
4.0 V
Collector-Emitter breakdown voltage, with base
open-circuited
BVCBO
8V
13 V
Collector-Base breakdown voltage, with emitter
open-circuited
BVEBO
1.2
1.2 V
Emitter-Base breakdown voltage, with collector
open-circuited
fT
57 GHz
36 GHz
Transition frequency: measured at 2.3 V, 30 mA
for BFP620, and 3 V, 30 mA for BFP640
ICmax
Gms
80 mA
50 mA
Maximum collector current
21 dB
24 dB
Maximum Stable Gain |S21/S12|
Measured at 2 V, 20 mA for BFP620, and 3 V,
20 mA for BFP640
0.14 pF
0.09 pF
Collector-Base Capacitance VCB = 2 V for
BFP620, 3 V for BFP640
0.1005
(-20 dB)
0.0682
(-23.3 dB)
Reverse Isolation
(1.8 GHz)
CCB
(f = 1 MHz)
S12 @ 2 V, 5 mA,
1.8 GHz
Key Points
•
•
•
•
BFP640 shows about 1 dB higher gain than BFP620 in a similar applications circuit. This is especially
advantageous at frequencies > 2 GHz.
Higher breakdown voltage of BFP640 is a nice feature:
- BFP640 may be used as a driver amplifier.
- BFP640 can provide potentially greater linearity if system supply voltage > 2.3 V (e.g. BFP640 can be safely
run at higher collector voltages than BFP620).
- Potential parts-count reduction in customer's circuits: in devices with 3 V supplies one no longer need worry
about "blowing" the transistor, as was the case with BFP620 => no special bias circuitry or voltage dropping
resistors are needed to run BFP640 straight off of 3 V supply rail.
Improved device reverse isolation (S12) of BFP640 gives better "stability" to device => increased stable gain
values. BFP640 is easier to stabilize as compared to BFP620 as a result of better reverse isolation value.
So far, experience has shown noise figure performance of BFP620 and BFP640 to be roughly equal.
Comments particular to this 2.4 GHz Application Circuit
•
•
•
•
•
Amplifier is unconditionally stable up to 6 GHz (e.g. K>1, B1>0 up to 6 GHz). Ample margin exists, with a
minimum K value of > 1.1
Simulated and measured results match reasonably well → available S-parameter data is of good quality
Test Conditions: VCC = 3.3 V, I = 5.3 mA, VCE = 3.0 V, T = 25 °C, network analyzer source power = -40 dBm
Total PCB Area of LNA: approximately 40 mm²
Total Parts Count, including transistor: 12 (does not include DC or RF connectors)
Application Note
5
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Bill of Material
Table 2
Bill of Material
Reference
Designator
Value
Manufacturer
Case Size
Function
C1
8.2 pF
Various
0402
Input DC block
C2
1 pF
Various
0402
Output DC block, output match, influences
input match
C3
0.1 µF
Various
0402
Low frequency ground at base (input 3rd
order intercept improved)
C4
8.2 pF
Various
0402
RF bypass / RF block
C5
8.2 pF
Various
0402
RF bypass / RF block / Influences stability
C6
0.1 µF
Various
0402
Bypass / block, some IP3 improvement
L1
5.6 nH
Murata LQG 10A low cost 0402
inductor
RF choke to DC bias on base, input
matching
L2
3.3 nH
Murata LQG 10A low cost 0402
inductor
Output RF match, DC feed to collector
R1
10 Ω
Various
0402
Stability, output matching
R2
43 kΩ
Various
0402
DC bias for base
R3
68 Ω
Various
0402
Drop supply voltage by 0.3 V, provide DC
feedback for bias compensation (beta
variation, temperature, etc.)
Q1
-
Infineon Technologies
SOT343
BFP640 SiGe, fT = 36 GHz
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, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Summary of LNA Data
T = 25 °C
Table 3
Summary of LNA Data
Parameter
Result
Target Specification
Comments
Frequency Range
2400 - 2483.5 MHz
2400 - 2483.5 MHz
Various portions of this range
are usable on a worldwide
basis
DC Current
5.3 mA
5.3 mA max.
Low current consumption
DC Voltage, VCC
3.3 V
3.3 V
Collector-Emitter Voltage, 3.0 V
VCE
3.0 V
Input P1dB
-10.5 dBm
Output P1dB
+3.4 dBm
rd
Input 3 Order Intercept
Gain
f1 = 2440 MHz, f2 = 2441 MHz,
-18 dBm each tone.
Excellent linearity
performance.
+15.3 dBm @ 2441 MHz
15.4 dB @ 2400 MHz
15.2 dB @ 2441 MHz
14.9 dB @ 2483.5 MHz
15 dB min.
Noise Figure
1.13 dB @ 2400 MHz
1.17 dB @ 2440 MHz
1.15 dB @ 2480 MHz
1.2 dB max.
Input Return Loss
12.4 dB @ 2400 MHz
13.4 dB @ 2441 MHz
14.4 dB @ 2483.5 MHz
10 dB min.
Output Return Loss
16.1 dB @ 2400 MHz
13.9 dB @ 2441 MHz
12.1 dB @ 2483.5 MHz
10 dB min.
Reverse Isolation
21.1 dB @ 2400 MHz
20.7 dB @ 2441 MHz
20.6 dB @ 2483.5 MHz
Application Note
7
Results much better than that
offered by low-cost integrated
solutions
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Schematic Diagram
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Figure 3
Schematic Diagram
Application Note
8
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Noise Figure, Plot, Center of Plot (x-axis) is 2440 MHz.
Tested at Room Temperature (T = 25 °C)
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Figure 4
Noise Figure
Application Note
9
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Noise Figure, Tabular Data
From Rohde & Schwarz FSEK3 + FSEB30
System Preamplifier = MITEQ SMC-2
Tested at Room Temperature (T = 25 °C)
Table 4
Noise Figure
Frequency
Noise Figure
2390 MHz
1.12 dB
2400 MHz
1.13 dB
2410 MHz
1.15 dB
2420 MHz
1.16 dB
2430 MHz
1.15 dB
2440 MHz
1.17 dB
2450 MHz
1.18 dB
2460 MHz
1.16 dB
2470 MHz
1.17 dB
2480 MHz
1.15 dB
2490 MHz
1.15 dB
Application Note
10
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Stability Factors K and B1
For unconditional stability, K > 1 AND B1 > 0. Note minimum K value is 1.09 at 2.313 GHz.
(For plot, actual measured LNA s-parameters are imported into the Eagleware GENESYS® design environment;
the software then calculates and plots K & B1.)
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Figure 5
Plot of K(f)
Application Note
11
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
LNA Gain Compression at 2441 MHz
!Power Sweep” with Network Analyzer (8753D) in CW Mode. Left edge of plot is input power = -25 dBm, right edge
is -5 dBm
Input P1dB ≅ -10.3 dBm
Output P1dB ≅ +3.9 dBm
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Figure 6
Plot of Gain Compression at 2441 MHz
Application Note
12
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Scanned Image of PC Board
Figure 7
Image of PC Board
Application Note
13
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Scanned Image of PC Board, Close-In Shot.
Figure 8
Image of PC Board, Close-In Shot
Application Note
14
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Input Return Loss, Log Mag
5 MHz to 6 GHz
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Figure 9
Plot of Input Return Loss
Application Note
15
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Input Return Loss, Smith Chart
Reference Plane = Input SMA Connector on PC Board
5 MHz to 6 GHz
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Figure 10
Smith Chart of Input Return Loss
Application Note
16
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Forward Gain
5 MHz to 6 GHz
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Figure 11
Plot of Forward Gain
Application Note
17
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Reverse Isolation
5 MHz to 6 GHz
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Figure 12
Plot of Reverse Isolation
Application Note
18
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Output Return Loss, Log Mag
5 MHz to 6 GHz
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Figure 13
Plot of Output Return Loss
Application Note
19
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Output Return Loss, Smith Chart
Reference Plane = Output SMA Connector on PC Board
5 MHz to 6 GHz
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Figure 14
Smith Chart of Output Return Loss
Application Note
20
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Two-Tone 3rd Order Intercept Test
Input Stimulus to LNA for Two-Tone 3rd Order Intercept Test.
f1 = 2440 MHz, f2 = 2441 MHz, -18 dBm each tone.
Tone power was measured with a power meter.
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Figure 15
Tow-Tone Test, Input Stimulus @ 2440 MHz
Application Note
21
Rev. 1.2, 2007-11-07
Application Note No. 130
The SiGe BFP640 as a 2.4 GHz Low Noise Amplifier (LNA)
Two-Tone 3rd Order Intercept Test
Output Response of LNA to Two-Tone 3rd Order Intercept Test.
f1 = 2440 MHz, f2 = 2441 MHz, -18 dBm each tone.
Input IP3 = -20 + (66.5 / 2) = +15.3 dBm
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Figure 16
Tow-Tone Test, LNA Response @ 2440 MHz
Application Note
22
Rev. 1.2, 2007-11-07