FPGA-Based Multichannel Digital Duty-Cycle Modulation and Application to Simultaneous Generation of Analog Signals

Abstract

The DCM (duty-cycle modulation) is used in industrial electronics as a special technique for producing switching time-varying periodic waves, with variable pulse width and modulation period. As an implication, unlike the fixed period of a PWM wave, the cyclic ratio of a DCM signal changes as a function of the modulating input according to a known function. However, most existing research works related to DCM-based instrumentation systems, are limited to single-channel contexts. In this paper, a multichannel DDCM (Digital Duty-Dycle Modulation) scheme is developed. It consists of an extended pre-computed DDCM data map which significantly reduces the overall DSP (digital signal processing) time, and a piece of dual DDCM counting logic with a downstream zero order holder per analog channel. It is used to build a well tested 4-channel FPGA-based signal generator with 10–12 bits resolution.

Keywords: Multichannel, DDCM, FPGA, low frequency generator, instrumentation systems