Description, Analysis and Simulation of a New Realization of Digital Filters

Abstract

This research considers a new realization of digital filters suitable for VLSI implementation. The method involves delta modulation which provides analog-todigital (binary) conversion. The output of a linear system is the convolution of the input and the system impulse response. This new digital filter requires that both the input and the impulse response be first converted to bit streams using delta modulation. These bit streams are then convolved. The result is an analog voltage which approximates the convolution of the analog functions. Direct convolution of the bit streams is difficult to realize with electrical circuits. A greatly simplified system with equivalent performance is a result of this research. This is called the reduced delta convolution (RDC) system (digital filter). The performance of the RDC system when used as a convolver and as a correlator is analyzed and verified by computer simulation. Analyses of the effects of self noise and external noise are included. Conclusions are that the RDC system has considerable potential as a digital filter when using integrated circuits. Realization requires considerably fewer components and simpler connections than other digital filters. A reason is that there are no multipliers required in the RDC system. The RDC system requires no synchronization, operates in real time and is easily programmed. Further, the RDC system has noise performance which is better than predicted by ordinary filter theory.