Delta modulation in DVM design

Existing digital voltmeters (DVM) do not sell as well as analog types having parallel capabilities for the simple reason that they cost more. Though the DVM has the superior performance to compete in the popular class of instruments, it must sell for less than 100 dollars. This means new thinking and radical alteration in present designs. New thinking developed the delta modulation DVM discussed here; it has high performance and is economical. Performance figures include an input impedance of >100 M/spl Omega/, an accuracy typically 0.3 percent of full scale, and a noise rejection figure of >60 dB at main frequencies >49 Hz. Power consumption is about 600 mW.