FROM EDN EUROPE: Polyphase DFT IP improves filter performance

You can build filters using polyphase DFT (discrete Fourier transform) cores that are now available as off-the-shelf IP (intellectual property) from UK signal-processing company RF Engines. The cores provide filter banks to process complex input data in higher radix designs in continuous real time, with no gaps in data, at 800M samples/sec or more. RF Engines pipelines the core designs—called Ventrix—for maximum throughput. They achieve better in-band ripple, stopband rejection, and roll-off than filters based on weighted FFTs. As with other IP that RF Engines has produced, the Ventrix cores are parameterised, and the company can optimise the number of polyphase taps to suit a particular application. You can use the cores in a range of signal-processing applications, communications systems, wideband filter banks, electronic-warfare and radar systems, medical instruments, and real-time spectral analysis. You can also use them in multichannel systems, in which you can interleave multiple low-speed channels through the high-speed core. In general, the company says, you can use the cores in any situation that uses FFT, digital downconversion, or multiple FIR filters.

RF Engines bases the polyphase designs, which can be critically sampled, twice oversampled, or n-times oversampled, on its pipeline FFT core. Silicon-efficiency metrics are indicated by implementation on FPGA; a 10-bit, three-tap, twice-oversampled 16,000-point version fits in a single Xilinx XC2V3000. Architectural designs have shown that a real-time, 1-million-point, five-tap, 14-bit, 20-MHz complex-data-rate version fits in a single XC2V6000 and three external SDRAMs.

RF Engines, +44 1983 550330, www.rfel.com.