Abstract: Electronic analogue to digital converters of the integrating type wherein a capacitor is successively charged by an input signal and discharged by a reference signal, the time required for discharge serving as a measure of the amplitude of the input signal.

Abstract: The analogue to digital converter is of the bipolar mark-space type and includes an integrator for integrating the analogue input signal to be converted. A square wave generator is connected to the input of the integrator so as to superimpose a triangular periodic signal on the output signal produced by the integrator.First and second level detectors are connected to compare the output signal from the integrator with first and second detector levels respectively to produce first and second control signals respectively when the magnitude of the output signal from the integrator exceeds the first level and falls below the second level respectively. Switch means responsive to the first and second control signals are provided to respectively apply first and second reference signals. The conversion interval is set equal in duration to the duration of an integral number of cycles of the periodic triangular signal.

Abstract: A ramp type analogue to digital converter including an integrating circuit the output of which is first set to a level dependent upon the magnitude of an analogue input voltage to be converted. A reference signal is then applied to ramp down the integrator output level to a datum level and the conversion is effected by counting clock pulses while the integrator output is ramping down to datum level. The magnitude of the reference signal and the numerical weighting of the clock pulses being counted are scaled down by a common factor when the ramp reaches a value close to the datum level so that the slope of the ram is reduced and the resolution of conversion is increased as it approaches datum. Thus, compared with a ramp type digital voltmeter having a constant slope discharge ramp and a given resolution, the discharge time is reduced for the same resolution of conversions.