CML Microcircuits
COMMUNICATION SEMICONDUCTORS
CMX980A
TETRA
Baseband Processor
Provisional Issue
D/980A/4 April 2004
1.0 Features
•
RRC Filters for both Tx and Rx
•
•
4 x 10-Bit D-A and 4 Input 10-Bit A-D
•
Transmit Output Power Control
•
Low Power 3.0 - 5.5Volt Operation
•
Effective Power down Modes
π
/4 DQPSK Modulation
•
2 x 14-Bit Resolution Sigma Delta D-A
•
2 x 16-Bit Resolution Sigma Delta A-D
1.1
Brief Description
This device is intended to act as an interface between the analogue and digital sections of a Digital Radio
System, and performs many critical and DSP-intensive functions. The chip is designed with the
necessary capability to meet the requirements for use in both mobile and base station applications in
Terrestrial Trunked Radio (TETRA) systems, but the architecture is sufficiently flexible to allow use in
other systems.
The transmit path comprises all the circuitry required to convert digital data into suitably filtered analogue
I and Q signals for subsequent up-conversion and transmission. This includes digital control of the output
amplitudes, digital control of the output offsets and fully programmable digital filters: default coefficients
provide the RRC response required for TETRA.
The receive section accepts differential analogue I and Q signals at baseband and converts these into a
suitably filtered digital form for further processing and data extraction. A facility is provided for digital
offset correction and the digital filters are fully programmable with default coefficients providing the RRC
response required for TETRA.
Auxiliary DAC and ADC functions are included for the control and measurement of the RF section of the
radio system. This may include AFC, AGC, RSSI, or may be used as part of the control system for a
Cartesian Loop.
2004 CML Microsystems Plc
CMLMICRO [ CML MICROCIRCUITS ]
