Quotient analogue frequency converter with direct digital output - has auxiliary capacitor for continuous storage capacitor current compensation

摘要

The quotient analogue frequency converter produces a signal whose frequency is proportional to the ratio between a measurement original and a comparison signal. The quotients of measurement and reference signal is converted directly into a digital value. The current flowing into a storage capacitor (2) as a result of the measurement signal is continuously compensated by discharging an auxiliary capacitor (8). Depending on the storage capacitor charge, a gate circuit applies to the auxiliary capacitor a voltage proportional to the reference signal. The voltage is applied to the auxiliary capacitor for a time short compared to the periodic time corresp. to the maximum count frequency. The charge is transferred to the storage capacitor or to earth via a diode branch (9,10).