CML Microcircuits CMX994 direct conversion receiver

CML Microcircuits has added the CMX994 direct conversion receiver to its family of RF integrated circuits.

The device targets the next generation of multimode software defined radios for wireless data and two-way radio applications. Its design provides the optimum route for onboard integration allowing a small RF receiver to be realised with a minimum of external components.

Until recently, most radios used the superheterodyne receiver, but enhancements in semiconductor technology have seen DCRx increasingly replace superhet as a technology of choice for radio receivers in many applications.

A DCRx mixes the wanted RF signal down to 0 Hz in a single quadrature mixing process using a local oscillator tuned to the wanted RF channel frequency.

Selectivity filtering and gain can now take place at baseband with practical, low-power, analog and digital circuits. DCRx also eliminates the need for an image reject filter.

Key features of the receiver include an on-chip VCO for VHF applications, an operating range of 100 MHz to 1 GHz, precision baseband filtering with selectable bandwidths and a small PCB area, typically less than 50% of a dual superhet. Another important feature is the single-ended RF connections meaning no baluns are required.