Variable centre frequency bandpass sigma-delta modulator

Abstract

In wideband surveillance and digital radio systems, there is a need to sweep the centre fequency of the data converter to detect a broadcast i nthe band of interest. Hence there is a need to design data converters with variable centre frequencies. Sigma-Delta modulators with programmable center frequency are chosen for this purpose. In this paper new resonators for a variable centre frequency bandpass Sigma-Delta modulator are presented. The new resonators have a centre frequency that extends from very low frequency up to half the sampling frequency. Simulation results of a fourth order discrete-time bandpass modulator employing the new resonator are presented using MATLAB and SPICE.