Direct conversion receiver IC boasts extended operating range for SDR

May 30, 2012 // By Jean-Pierre Joosting
Through an on-going research and development programme, CML Microcircuits has extended the operating range of the CMX994 direct conversion receiver (DCRx) IC to cover 50 MHz to 940 MHz, enabling the IC to address a wider range of software defined radio (SDR) demands.

The CMX994 is a receiver IC featuring I/Q demodulators intended for use as a direct conversion receiver. The device targets the next generation of multi-mode software defined radios for wireless data and two-way radio applications. Its design provides the optimum route for on-board integration, allowing a small RF receiver to be realised with a minimum of external components in both zero IF and low IF systems.

A DCRx mixes the wanted RF signal down to 0-Hz in a single quadrature mixing process using a local oscillator (LO) tuned to the wanted RF channel frequency. Selectivity filtering and gain can now take place at baseband with practical, low power, analogue and digital circuits. DCRx also eliminates the need for an image-reject filter.

The CMX994 DCRx IC offers excellent RF performance, exceptional IP2 from I/Q mixers and is suitable for modulation schemes including: QAM, 4FSK, GMSK and pi/4-DQPSK. Key features of the device include on-chip VCO for VHF applications, on-chip LNA, precision baseband filtering with selectable bandwidths and the smallest PCB area, typically less than 50% of a dual superhet.

It is available now, operates at 3.0 - 3.6 V, and comes in a Q4 40-pin VQFN package.