High performance analog to digital converter for integrated circuits

摘要

An analog to digital converter suitable for fabrication according to integrated circuitry technology. The voltage to be converted is applied to a storage capacitor which is pulse discharged in discrete equal amounts determined by a voltage controlled constant current source. The pulses are counted and the total represents the input voltage. The current of the constant current source, and concomitantly the discrete pulsed discharge amounts, is varied during a calibrate mode depending upon any detected error. A known reference voltage is applied to the storage capacitor which is then pulsed down by the voltage controlled current source. Any deviation in the time of discharge, as compared to the known time (number of pulses) to discharge the capacitor, varies the voltage which controls the current magnitude of the constant current source.