Newnes Digital Logic IC Pocket Book

8

Pulse Generator Circuits

Digital ICs must, in general, be driven or clocked by clean input waveforms that switch between normal logic levels and have very sharp leading and trailing edges; such waveforms can be generated by suitably using standard logic ICs, or via dedicated waveform-generator ICs. This chapter explains digital waveform generator basics, and shows a variety of practical pulse waveform ‘clock’ generator circuits; Chapter 9 continues the theme by taking a detailed look at practical squarewave generator circuits.

Waveform Generator Basics

Most digital waveform generator circuits fit into one or other of the four basic categories shown in Figure 8.1(a) to (d). Schmitt trigger circuits (a) produce an output that switches abruptly ...