A single-bit narrow-band bandpass digital filter

Abstract

An efficient structure for single-bit bandpass bit-stream filtering is presented. This structure contains only one multiplication arithmetic found in traditional filtering operations, whilst producing a filtered single-bit output. This work is built on a previous work by the authors where a low-pass ternary filter has been designed; the filter contains an efficient ternary filter cascaded with a recursive sigma-delta filter. The theme of these works has been to efficiently and simply filter signals using single-bit signal processing techniques. Keeping with this theme we propose in this work a bandpass single-bit filter that consists of a ternary finite-impulse-response (FIR) filter and a sigma-delta modulator, both designed to operate in the bandpass mode. As the ternary filter produces a multi-bit output, a sigma-delta modulator is necessary to remodulate the filtered signal back into the single-bit format.