Direct conversion I/Q demodulator targets next generation of multi-mode SDRs for wireless data
The 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.
Until recently, most radios have used the superheterodyne (Superhet) receiver, however enhancements in semiconductor technology have enabled the integration of DCRx, allowing it to become the technology of choice for radio receivers in many applications.
A DCRx mixes the wanted RF signal down to 0Hz 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.
Key features of the CMX994 include on-chip VCO for VHF applications, an operating range of 100MHz to 600MHz, precision baseband filtering with selectable bandwidths and the smallest PCB area, typically less than 50% of a dual superhet.
The single ended RF connections mean no baluns are required.
The small size and flexibility of Direct Conversion make it a key element for the next generation of multi-mode software defined radios (SDR) for wireless data and digital two-way radio applications.
Availability
The CMX994 is available now, operates at 3.0 – 3.6 V, and comes in a Q4 40-pin VQFN package.
More information about the CMX994 direct conversion receiver at
www.cmlmicro.com/Products/Index.asp?/Products/RF/CMX994.htm
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