CMX981 Consumer Microcircuits Limited, CMX981 Datasheet - Page 11

• Manufacturer Part Number: CMX981
• Description: Advanceddigital Radio Baseband Processor (tetra Etc.)
• Manufacturer: Consumer Microcircuits Limited

Advanced Digital Radio Baseband Processor
5.
5.1
 2002 CML Microsystems Plc
General Description
Tx Functions
Rx Functions
Auxiliary Functions
Voice Codec Functions
Serial Interface
Programmable FIR Filter Architecture
A common FIR filter architecture is employed within both the transmit and receive data paths. The
filters use a small local static RAM for efficient data and coefficient storage during filter operations,
together with a dedicated hardware multiplier and accumulator for each filter.
On reset, the coefficient RAMs are loaded with default values that provide the required response
to meet the needs of a TETRA baseband system (this takes 1 sample period). In the default
modes the dynamic range of arithmetic units are sufficient for all normal input data levels without
causing overflows. Each filter has an odd number of default coefficients, which are symmetrical,
giving a linear phase response. These coefficients may be overwritten to adapt to other systems
or compensate for deficiencies outside the device. However the user is then responsible for
ensuring that user supplied values do not cause arithmetic overflows to occur within an
accumulation cycle. Overflow logic within each filter can detect such events and cause interrupts
to be generated under user control.
Four word deep FIFO
Bypassable /4 DQPSK modulator
Programmable FIR filters
Transmit ramping function
Gain, phase and offset adjustment
14-bit resolution sigma delta DAC converter
16-bit resolution sigma delta ADC converter
Anti-alias and decimation filter with adjustable sampling point
Gain and offset adjustment
Programmable FIR filters
6 input 10-bit ADC converter with internal sample and hold
4 10-bit DAC converters
RAM driven DAC mode
14-bit resolution sigma delta ADC and DAC converters
100mW into 8 load differential speaker amplifier
16.5mW into 32 load earpiece amplifier
Ring tone generator
Sidetone addition
Three DSP compatible serial ports
One serial port can be configured as a C-bus interface
Selectable serial clock rate up to MCLK
Bidirectional mode
Hardware interlock modes
Auto power save mode
11
CMX981
D/981/1