RC2798 Datasheet, PDF (1/12 Pages) Fairchild Semiconductor – Integrated QAM IF Downconverter

RC2798
Integrated QAM IF Downconverter
www.fairchildsemi.com
Features
• RF input frequency range 30 to 250MHz
• On chip VCO with LO frequency range 30 to 250MHz
• IF amplifier with AGC setting
• High dynamic range -9dBm IIP3
• On chip Video Amplifier
• Built in ESD protection
• Supply voltage range 5 to 10 V
• Space saving 20-Lead TSSOP package
Applications
• Digital Set-top receivers
• Cable modems
• Internet surfboards
• Network Interface Modules
• Multimedia PCs
Description
The RC2798 is an integrated solution for the down-
conversion of QAM IF signals in the front-end design of
cable modem and set-top receivers. It is intended for use in
64QAM and 256QAM IF downconversion applications.
The RC2798 integrates IF amplifier with AGC , mixer, VCO,
and a video amplifier on a single chip. It accepts the QAM IF
signals via SAW filter and downconverts it to 5MHz
baseband signal.
The baseband signal can be digitized using Fairchild
Semiconductor’s 8 bit A/D (TMC1175 series) or 10bit A/D
(TMC1185 series) and decoded further with a QAM
demodulator. The IF, Oscillator and Mixer section work at
5V. The video amplifier works at 5V to 10V. The RC2798 is
available in a 20 Lead TSSOP package.
Block Diagram
AGC_IN1 1
AGC_IN2 2
VAGC 3
VCC MIX 4
OSC_OUT 5
GND 6
B2 7
C1 8
C2 9
B1 10
RC2798
AGC + MIX
20 GND
19 MIX_OUT2
18 MIX_OUT1
17 G1A
16 G1B
15 VampIn1
LO
14 VampIn2
13 VccAmp
VideoAmp
12 OUT1
11 OUT2
Rev 1.0.0
PRELIMINARY INFORMATION describes products that are not in full production at the time of printing. Specifications are based on design goals
and limited characterization. They may change without notice. Contact Fairchild Semiconductor for current information.