Abstract:
This accurate and stable analog to digital conversion system and circuits useful therewith is based upon selective counting of high frequency electrical signal oscillations generated by a phase locked frequency multiplication network. The network contains only low cost components. Accuracy and stability derive from maintenance of predetermined phase locked relationship between the signal derived through frequency division of the network output signal and a cyclic reference signal which is also the reference for gating the encoding counts (i.e. the reference for measurement of the analog parameter which is to be encoded). The network output frequency is a harmonic of the frequency of the reference signal. Feedback phase control is developed through interaction of the frequency divided network output with the reference signal in a phase comparator circuit. A novel circuit arrangement for generating the reference signal in the form of ramp oscillations is also disclosed.