HSP50306
February 1998
Digital QPSK Demodulator
Description
The HSP50306 is a 6-bit QPSK demodulator chip designed
for use in high signal to noise environments which have some
multipath distortion. The part recovers 2.048 MBPS data from
samples of a QPSK modulated 10.7MHz or 2.1MHz carrier.
The chip coherently demodulates the waveform, recovers
symbol timing, adaptively equalizes the signal to remove
multipath distortion, differentially decodes and multiplexes the
data decisions. 8-A lock signal is provided to indicate when
the tracking loops are locked and the data decisions are valid.
To optimize performance, a gain error feedback signal is
provided which can be 鏗乴tered and used to close an I.F. AGC
loop around the A/D converter.
The QPSK demodulator derives all timing from CLKIN. The
chip divides this clock by 2 to provide the sample clock for the
external A/D converter. The -27 version operates at a clock
input of 26.97MHz and demodulates a 10.7MHz QPSK signal
to recover the 2048 KSPS data. The -25 version operates at a
clock input of 25.6MHz and demodulates a 2.1MHz QPSK
signal to recover the 2048 KSPS data. Variation from these
CLKIN frequencies will progressively degrade the receive
data rate, the receive IF, acquisition sweep rate, acquisition
sweep range and loop bandwidths as the deviation increases
from normal CLKIN. Details on the maximum allowable devia-
tion are found in the Input Characteristics section. The
HSP50306 processes 6-bit offset binary data. 4-bit data pro-
vides adequate performance for many applications.
Features
鈥?25.6MHz or 26.97MHz Clock Rates
鈥?Single Chip QPSK Demodulator with 10kHz Tracking
Loop
鈥?Square Root of Raised Cosine (
偽
= 0.4) Matched
Filtering
鈥?2.048 MBPS Reconstructed Output Data Stream
鈥?Bit Synchronization with 3kHz Loop Bandwidth
鈥?Internal Equalization for Multipath Distortion
鈥?6-Bit Real Input: Digitized 10.7MHz or 2.1MHz IF
鈥?Level Detection for External IF AGC Loop
鈥?0.1s Acquisition Time
鈥?10
-9
BER
鈥?<116mA on +5.0V Supply
Applications
鈥?Cable Data Link Receivers
鈥?Cable Control Channel Receivers
Ordering Information
PART NUMBER
HSP50306SC-27
HSP50306SC-2796
HSP50306SC-25
HSP50306SC-2596
TEMP.
RANGE (
o
C)
0 to 70
0 to 70
0 to 70
0 to 70
PACKAGE
16 Ld SOIC
Tape and Reel
16 Ld SOIC
Tape and Reel
M16.3
PKG.
NO.
M16.3
Block Diagram
I
4 TAP
ADAPTIVE
EQUALIZER
I
COS
AGCOUT
ADCLK
CLKIN
RESET
TEST
CARRIER
LOOP FILTER
LEVEL
DETECT
SIN
NCO
TIMING
GENERATOR
BIT PHASE
DETECTOR
CARRIER
PHASE
DETECT
Q
DIFF.
DECODE/
MUX
DATAOUT
DIN0-5
6
Q
BIT SYNC
LOOP FILTER
LOCK
DETECT
LOCK
CLKOUT
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
http://www.intersil.com or 407-727-9207
|
Copyright
漏
Intersil Corporation 1999
File Number
4162.2
8-272
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