SL2009
Dual stage IF amplifier for cable tuners
DS5507
ISSUE 1.4
March 2002
Features
•
•
•
•
•
Single chip solution for tuner IF gain and AGC
Contains 34 dB of AGC shared between two
AGC stages
Design optimised for high signal handling with
low inter-modulation spurious generation
I/O ports optimised to interface with standard
SAW filters
ESD protection (Normal ESD handling
procedures should be observed)
Ordering Information
SL2009/KG/NP1T (Tape and Reel)
SL2009/KG/NP1S (Tubes)
The devices includes two stages of IF gain which are
both optimised to interface with inter-stage filters.
Both stages contain independent AGC facility, and
the first stage contains a level detect for control of the
tuner AGC.
Applications
•
•
Cable Network interface modules and tuners
Data communications systems
IFIP
IFIPB
VCCIF
AGC2
IFOP
1
16
VCCSAW
SDRIVEOP
SDRIVEOPB
AGCOUT
AGC1
SDRIVEIP
SDRIVEIPB
Description
The SL2009 is a dual IF amplifier intended for
application in cable tuners, and integrates all of the
IF gain and AGC required to deliver 1Vp-p in a
standard tuner configuration.
VEE
IFOPB
VEE
8
9
AGCBIAS
NP16
Figure 1 - Pin allocation
(12)
AGC1
AGC
SENDER
AGC
SENDER
AGCBIAS (9)
AGCOUT (13)
(11) SDRIVEIP
(10) SDRIVEIPB
(15)
SDRIVEOP
SAW
Driver
VccSAW (16)
Vee (6,8)
VccIF (3)
(14) SDRIVEOPB
(1) IFIP
(2) IFIPB
AGC
IFOP (5)
IFOPB (7)
(4) AGC2
SENDER
Figure 2 - Block diagram
1
SL2009
Characteristics
SAWF driver stage
Input operating range
Input NF, referred to 2k
Ω
OPIP3
Gain
IF Amplifier stage
Input operating range
Input NF, referred to 2 k
Ω
OPIP3
Gain
Table 1 - Quick reference data
30 - 50
6
8
20 - 40
MHz
dB
dBV
dB
30 - 50
4
4
14 - 28
MHz
dB
dBV
dB
Units
Functional Description
The SL2009 is an IF amplifier intended primarily for
application in cable tuners, and requiring a minimum
external component count to integrate the IF gain,
AGC facility and level detect.
The pin allocation is contained in figure (1) and the
block diagram in figure (2)
different AGCBIAS conditions is contained in figure
(4).
See figures (5) and (6) for SAW amplifier input and
output impedances respectively.
IF amplifier section
In normal application the output of the SAW filter is
coupled differentially to the input preamplifier of the
IF amplifier, which presents a differential 2 k
Ω
3 pF
load to the SAW filter and is optimised for both signal
handling and NF. See figure (8) for IF amplifier input
impedance.
The input preamplifier, then interfaces with the
variable gain stage which is under control of the
second AGC sender and this provides for 20 dB of
gain control. The typical AGC characteristic is
contained in figure (7)
The AGC output is then connected to the output
driver stage, which presents a low differential output
impedance, see figure (9) and is optimised for output
signal handling.
The typical key performance data at 5V Vcc and 25
deg C ambient are shown in the table entitled
'QUICK REFERENCE DATA'.
SAWF driver stage
In normal application the IF output of the tuner,
which is typically in the region of 30-50 MHz, is
interfaced to input preamplifier of the SAWF driver
stage, which is optimised for both signal handling
and NF referred to 2 k
Ω
.
The input preamplifier interfaces with the variable
gain stage, which is under control of the first AGC
sender and provides for 14 dB of gain control. The
typical gain characteristic is contained in figure (3).
The AGC stage then interfaces with the output buffer
amplifier, which presents a balanced 50
Ω
drive to
the IF SAW filter and offers high signal handling to
minimise intermodulation distortions.
The SAWF amplifier also incorporates a level detect
block whose output AGCOUT, can be used to control
the gain of the SAWF amplifier or other gain stages
in front of the SL2009. This AGC characteristic can
be set up by a "current set" resistor connected
between the AGCBIAS input and Vee. The typical
characteristic curve for AGC set, output level under
2
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