A Design of a Period-to-Frequency Analog Converter

A method for designing a period-to-analog converter is described. The device accepts input signals of varying frequency and converts the period of the waveform to a time inverse voltage Vi(t). This voltage is sampled at the end of the period, and this information is held over the following interval. The analog derived from the input signal is a voltage proportional to the repetition rate. The approach to generating the time inverse voltage is based on Willer's general method of approximating decaying functions with a sum of exponential functions. The described method has been utilized to develop a device for monitoring physiological signals. Results demonstrating the performance of the instrument are presented. The method is directly applicable to function generation in general and could be of importance for analog computers.