Applications Note No. 074
Silicon Discretes
A 35 dB Gain-Sloped LNB I.F. Amplifier for Direct Broadcast Satellite
Television Applications using the BGA430 & BGB540 Silicon MMICs
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Gain = 32 – 37 dB from 950 – 2150 MHz (positive gain slope)
Low Power Consumption: 40mA at +5.0 Volts
Exceptionally low Noise Figure: less than 3 dB
Low Cost, Low Parts Count
High Reverse Isolation
Output Compression point: +1 dBm minimum
(May be increased with higher DC bias level)
Suitable for European, Asian & North American DBS
LNB I.F. Amplifier Chains for 950 – 1450 and 950 – 2150 MHz
1. Overview
Infineon’s
BGA430 Broad Band High Gain
Low Noise Amplifier
and
BGB540 Active
Biased Transistor
are shown in an
Intermediate-Frequency
(“I.F.”)
amplifier
application targeted for the I.F. chains of
European, Asian and North American Direct-
Broadcast Satellite (DBS) Low Noise Block
Amplifier / Downconverters (LNBs).
A summary of key performance parameters for
the complete LNB I.F. Amplifier is given in
Table
1
to the right.
The reader is referred to
Appendix A
on page 21 for complete electrical
data including minimum, maximum, mean value,
and standard deviation for the lot of Printed
Circuit Boards (PCBs) tested.
Appendix B
on
page 22 gives information on performance over
the –40 to +85 °C temperature range.
Section 2
of this applications note provides a
brief description of the BGA430 and BGB540
MMICs.
Section 3
gives some general Direct
Broadcast Satellite system information, and is
included to provide a general background.
Section 4
provides details on the PC Board
used, including photos, a Bill of Material (BOM)
and a PCB cross-sectional diagram.
Section 5
describes using the BGA430 MMIC as a stand-
alone DBS I.F. Amplifier block, and covers
design issues unique to BGA430.
Section 6
addresses the question “why might one want a
positive gain slope I.F. Amplifier” and
Section 7
gives measurement results on the complete
gain-sloped amplifier using both BGA430 &
BGB540.
Table 1.
complete
Amplifier.
Typical performance for the
BGA430+BGB540
LNB
I.F.
Conditions: Temperature=25°C, V=5.0 Volts, n=25 units,
Z
S
=Z
L
=50Ω, network analyzer source power = -40 dBm
Parameter
Input Return Loss, dB
Gain, dB
Reverse Isolation, dB
Output Return Loss, dB
Noise Figure, dB
Output P
1dB
, dBm
Input IP
3
, dBm
Frequency, MHz
950
1450
2150
26.0
27.3
12.0
33.0
37.2
37.2
>50
>50
>50
13.7
13.4
13.1
2.4
2.4
2.6
+1.7
+4.9
+7.9
-20.8
-22.5
-18.9
Please note that the reference planes for all
measurement data shown in
Table 1
are at the
PC board’s SMA RF connectors; e.g. no PCB
loss is extracted from the numbers given.
1 / 24
19-November-2002
AN 074 Rev E
INFINEON [ INFINEON TECHNOLOGIES AG ]
