Analogue front end for digital radio bridges DSP and RF

Paul Boughton

CML Microcircuits has developed an Analogue Front End (AFE) for digital radios that bridges the gap between a digital radio’s RF section and the DSP/FPGA.

Specifically designed to meet the needs of a Software Designed 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.

The CMX983 is suitable for radio systems employing modulation bandwidths up to 25.8kHz, and it is particularly suited to satellite communication, high-performance wireless data and professional two-way radio systems. The device is highly configurable, supporting numerous sample rates and filtering characteristics. This configurability enables a high level of functionality, integration and connectivity with CML's RF building block ICs. It also 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 operating at up to 1GHz.

The AFE meets the low operating power requirements of new SDR based terminals and is powered from separate 3.3V and 1.8V power supplies. The PLL charge pumps can also be operated at up to 4.75V, providing low noise operation.

The CMX983 is available in a small 64-lead VQFN package.

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