434MHz LNA for RKE Using the 2SC5245A

434MHz LNA for RKE
Using the 2SC5245A
Application Note
http://onsemi.com
Overview
This application note explains about ON Semiconductor’s 2SC5245A which is used as a
Low Noise Amplifier (LNA) for RKE (Remote Keyless Entry).
The 2SC5245A is a silicon bipolar transistor best suited for high-frequency applications
which is assembled in the 3-pin surface mount package.
For information about the performance, please refer to the datasheet of this product.
Since the evaluation board is adjusted to achieve optimal performance in RKE (434 MHz),
the product can provide 14dB gain and 1.45dB noise figure.
A standard material FR4 is used for the printed circuit board (PCB).
Please note that the losses of the PCB and the SMA connector are not excluded from the
noise figure.
Semiconductor Components Industries, LLC, 2014
March, 2014 – Rev. 0
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434MHz LNA for RKE Using the 2SC5245A
■Summary of Data
Ta = 25 °C, Input Power = -40 dBm
Parameter
DC Voltage
DC Current
Power Gain
Noise Figure
Input Return Loss
Output Return Loss
Isolation
Gain 1dB
Compression
Input Power
Input 3rd Order
Intercept Point
Symbol
Condition
Result
Unit
Vcc
3.0
V
Icc
1.96
mA
Gp
f = 434 MHz
14.0
dB
NF
f = 434 MHz
1.45
dB
RLin
f = 434 MHz
6.2
dB
RLout
f = 434 MHz
13.0
dB
ISL
f = 434 MHz
20.2
dB
Pin1dB
f = 434 MHz
-20
dBm
IIP3
f1 = 433 MHz
f2 = 434 MHz
-10
dBm
Pin = -35 dBm
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434MHz LNA for RKE Using the 2SC5245A
■Circuit Design
Vcc = 3V
C5
R1
R2
C4
L2
L1
OUTPUT
INPUT
L3
C1
C3
C2
TR1
L4
■Evaluation Board
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434MHz LNA for RKE Using the 2SC5245A
■Bill of Materials
Item
Symbol
Value
Manufacturer
Size
Bip-Tr
TR1
2SC5245A
ON Semiconductor
SC70
C1
C2
10 pF
6 pF
Murata GRM155
Murata GRM155
1005
1005
C3
4 pF
Murata GRM155
1005
C4
150 pF
Murata GRM155
1005
C5
0.1 uF
Various
1608
R1
470 Ω
Various
1005
R2
68 kΩ
Various
1608
L1
22 nH
TDK MLG1005S
1005
L2
10 nH
TDK MLG1005S
1005
L3
39 nH
TDK MLG1005S
1005
L4
2.2 nH
TDK MLG1005S
1005
-
FR4
-
19 x 12 mm
Capacitor
Resistor
Inductor
Material
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434MHz LNA for RKE Using the 2SC5245A
Power Gain ‐ dB
■Power Gain
20
18
16
14
12
10
8
6
4
2
0
0
200
400
600
Frequency ‐ MHz
800
1000
200
400
600
Frequency ‐ MHz
800
1000
Isolation ‐ dB
■Isolation
0
‐5
‐10
‐15
‐20
‐25
‐30
‐35
‐40
‐45
‐50
0
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434MHz LNA for RKE Using the 2SC5245A
■Input Return Loss
Input Return Loss ‐ dB
0
‐5
‐10
‐15
‐20
‐25
‐30
0
200
400
600
Frequency ‐ MHz
800
1000
200
400
600
Frequency ‐ MHz
800
1000
■Output Return Loss
Output Return Loss ‐ dB
0
‐5
‐10
‐15
‐20
‐25
‐30
0
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434MHz LNA for RKE Using the 2SC5245A
Noise Figure ‐ dB
■Noise Figure
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
300
350
400
450
500
Frequency ‐ MHz
550
600
S11,S21,S12,S22 ‐ dB
■S11, S21, S12, S22 Wide Span
20
10
0
‐10
‐20
‐30
‐40
‐50
‐60
‐70
‐80
S21
S11
S22
S12
10
100
1000
Frequency ‐ MHz
10000
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434MHz LNA for RKE Using the 2SC5245A
S(3,3)
■Smith Chart
Input Return Loss
434 MHz
fre400
q (400.0MHz
500.0MHz)
MHz toto500
MHz
S(4,4)
■Smith Chart
Output Return Loss
434 MHz
fre400
q (400.0MHz
500.0MHz)
MHz toto500
MHz
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434MHz LNA for RKE Using the 2SC5245A
■Gain 1dB Compression Point
0
Output Power ‐ dBm
‐5
‐10
‐15
‐20
‐25
‐30
‐45
‐40
‐35
‐30
‐25
‐20
Input Power ‐ dBm
‐15
‐10
■Input 3rd Order Intercept Point
f1 = 433 MHz, f2 = 434 MHz, Pin = -35 dBm
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434MHz LNA for RKE Using the 2SC5245A
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