Download BDTIC Application Note No. 016

A pp li c at i on N ot e , R ev . 2. 0 , N ov . 2 00 6
A p p li c a t i o n N o t e N o . 0 1 6
L o w - N o i s e- A m p l i f i e r o p t i m i z e d f o r i n p ut a n d
o u t p u t r e tu r n l os s a t 1 .9 G H z u s i n g B F P 4 2 0
BDTIC
R F & P r o t e c ti o n D e v i c e s
www.BDTIC.com/infineon
BDTIC
Edition 2006-11-14
Published by
Infineon Technologies AG
81726 München, Germany
© Infineon Technologies AG 2009.
All Rights Reserved.
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www.BDTIC.com/infineon
Application Note No. 016
Low-Noise-Amplifier optimized for input and output return loss at 1.9 GHz using BFP420
Revision History: 2006-11-14, Rev. 2.0
Previous Version:
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Subjects (major changes since last revision)
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BDTIC
Trademarks
SIEGET® is a registered trademark of Infineon Technologies AG.
Application Note
3
www.BDTIC.com/infineon
Rev. 2.0, 2006-11-14
Application Note No. 016
Low-Noise-Amplifier optimized for input and output return loss at 1.9 GHz
1
Low-Noise-Amplifier optimized for input and output return loss at
1.9 GHz using BFP420
This application note provides general information, print layout and list of used components, circuit layout and
measured data of a low noise amplifier at 1.9 GHz using SIEMENS SIEGET®25 BFP420. This circuit is optimised
for return loss values.
Data at 1.9 GHz (3 V and 5 mA)
Gain:
14 dB
IP3out::
NF:
RLin::
RLout:
8 dB
1.65 dB
BDTIC
>13 dB
>18 dB
The amplifier application circuit has been optimised to achieve optimum noise figure and good stability at 1.9 GHz,
combined with low operating current and voltage for use in handheld equipment.
The transistor is matched using microstrip lines at input and output in conjunction with capacitors to ground. The
added emitter inductance reduces gain but it provides the best overall matching conditions for maximum gain and
minimum noise figure. The active bias controller BCR400W is used to provide bias stability over the operating
temperature range. For additional information on this part please refer to application note No.014. The collector
resistor is used for increase stability for the RF-transistor and omits the need to use λ/4 transmission lines for
biasing. In order to avoid AF oscillations for the BCR400W, the blocking capacitor at the base of the RF transistor
should be at least ten times the value used at collector.
IC1
2
C5=4.7µF
1
BCR400W
C4=1nF
4
R3=150 Ohm
C7=1nF
C3=22pF
C6=22pF
R2=150 Ohm
R1=1k
RFin
+3V
3
RFout
TrL4
TrL1
C2=1.2pF
C1=1.5pF
Tr1=BFP420
TrL2
TrL3
AN016_application.vsd
Figure 1
Application
Application Note
4
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Rev. 2.0, 2006-11-14
Application Note No. 016
Low-Noise-Amplifier optimized for input and output return loss at 1.9 GHz
25mm x 20mm
150 Ohm
0 Ohm
BDTIC
4.7µF
BCR400W
1 nF
22 pF
1 nF
1.5 pF
22 pF
150 Ohm
1k Ohm
1.2 pF
BFP420
AN016_PCB_Layout.vsd
Figure 2
PCB Layout and Component Placement
Application Note
5
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Rev. 2.0, 2006-11-14
Application Note No. 016
Low-Noise-Amplifier optimized for input and output return loss at 1.9 GHz
Table 1
Component
Component
Value
Unit
Size
Comment
R1
1
kΩ
0603
Bias
R2
150
Ω
0603
To improve stability and output return loss
R3
150
Ω
0603
Bias resistor for BCR400W / collector current
C1
1.5
pF
0603
Input match
C2
1.2
pF
0603
Output match
C3
22
pF
0603
RF-short
C4
1
nF
0603
RF-short
C5
4.7
µF
0603
RF-short
BDTIC
C6
10
nF
0603
RF-short
C7
22
pF
0603
RF-short
C8
1
nF
0603
RF-short
SOT343
SIEGET® BFP420
Tr1
TrL1
Input match
TrL2
Emitter-microstrip-line
TrL3
Emitter-microstrip-line
TrL4
Output match
IC1
Substrate
Application Note
SOT343
FR4
BCR400W, active bias controller
h = 0.5 mm, εr = 4.5
6
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Rev. 2.0, 2006-11-14
Application Note No. 016
Low-Noise-Amplifier optimized for input and output return loss at 1.9 GHz
Measurements
LOG MAG.
S21
S12
10.000 dB/DIV
LOG MAG.
10.000 dB/DIV
1
BDTIC
1
GHz
0.100000
0.100000
10.000 dB/DIV
LOG MAG.
S11
3.000000
S22
10.000 dB/DIV
LOG MAG.
1
1
GHz
0.100000
1
3.000000
GHz
0.100000
3.000000
3.000000
GHz
1.9 GHz
AN016_M easurem ents.vsd
Figure 3
Measurements
Application Note
7
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Rev. 2.0, 2006-11-14