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Analogue Front End (AFE) for Digital Radio

CMX983 - AFE including two RF fractional-N synthesisers


  • Rx channel
    - Two 16-bit Σ-Δ A/D Converters
    - Programmable Channel Filter
  • Tx Channel
    - Two 14-bit Σ-Δ D/A Converters
    - Programmable Channel Filter
  • RF Support
    - Two 2.1GHz Fractional-N Synthesisers
  • Auxiliary Functions
    - 10-bit A/D Converter supporting (8-inputs)
    - Five Analogue Comparators
    - Nine 10-bit D/A Converters
  • DSP Interface
    - BUS Control and Configuration Port
    - Fast Serial Interface for Rx/Tx Data
  • Duplex and Half duplex operation
  • Direct connection to:
    - CMX998 Cartesian Loop Transmitter
    - CMX994 Direct Conversion Receiver
  • Low power operation
    - 3.3V and 1.8v supplies
  • Small 64-lead VQFN Package
  • Software Defined Radio (SDR)
  • Satellite Communication
  • Wireless Data Terminals
  • Digital PMR/LMR Radio
    - TETRA
    - DMR
    - APCO P25
    - PDT

The CMX983 is an Analogue Front End (AFE) IC that bridges the gap between a digital radio’s RF section and the DSP/FPGA.

Specifically designed to meet the needs of a Software Defined Radio (SDR), the CMX983 performs critical DSP-intensive functions, provides dual channel analogue to digital and digital to analogue conversion, includes two RF fractional-N synthesisers, and embeds a host of auxiliary ADCs and DACs for use within the radio system.

Suitable for radio systems employing modulation bandwidths up to 50kHz in wideband mode and up to 25kHz in narrowband mode. 

The CMX983 meets the low operating power requirements of new SDR based terminals and is powered from separate 3.3V and 1.8V power supplies.  A facility is provided to allow the PLL charge pumps to be operated at up to 4.75V, providing low noise operation. The CMX983 is available in a small 64-lead VQFN package.

The CMX983 is highly configurable, supporting numerous sample rates and filtering characteristics. This configurability enables a high level of functionality,  integration and connectivity with RF building block ICs.  The CMX983 connects seamlessly with CML’s CMX994 Direct Conversion Receiver and the CMX998 Cartesian Feedback Loop Transmitter, to provide a complete small form factor, RF-to-digitised baseband solution.

The device is widely used in high performance wireless data systems including: military and satellite communication, professional two-way radio and wireless telemetry applications.

Block Diagram


Design Support Information

DMR Rx Filter A set of CMX983 receive channel filter coefficients suitable for baseband filtering in DMR applications
Rx sinc filter CMX983 receive channel compensation coefficients using sinc filtering
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