Method for obtaining a nonlinear relationship between the input voltage and output frequency for operating in the case of a voltage-to-frequency converter

摘要

1,124,707. A/D converters. SIEMENS A.G. 24 Feb., 1967 [25 Feb., 1966], No. 9068/67. Addition to 1,076,811. Heading G4H. The analogue input is supplied to an amplifier having an integrating capacitor from which charge increments are subtracted when the output of the integrator exceeds a threshold level, the size of the increments varying linearly with the number of times the threshold is exceeded within a preset measuring period. The measuring period is determined by a timer enabling a counter for the preset time interval. The counter receives the output pulses from the threshold detector and determines, by way of a D/A converter, the voltage to which a capacitor is charged. Each time the counter receives a pulse, the last-mentioned capacitor is switched to the amplifier to decrement the integrated charge, the size of the decrement increasing linearly with the count registered. The digital output is proportional to the square-root of the input. The size of the charge increments may be held constant until a predetermined count has been attained.