Application of a single electron transistor in a rate controlled oscillator

Abstract

An application of the nano-electronic quantum device single electron transistor (SET) is presented in this thesis work. With the operating principle described, a circuit is proposed with the name of 'rate controlled oscillator'. The proposed circuit takes any small signal voltage wave as input variable and produces a pulse train of square wave with low duty cycle. The frequency of the pulses occurring at the output node is directly proportional to the slope (dv/dt) of the input voltage signal. The circuit thus generates a pulse with frequency proportional to the rate of change of the input signal and hence the name is given 'rate controlled oscillator'. This circuit is expected to find its application in many daily life applications as well as in many high end research projects. A proposed adaptive sample and hold circuit which uses SET based rate controlled oscillator as its sampling frequency generator is also presented which is named 'adaptive sample and hold circuit'. The adaptive sample and hold circuit is capable of detecting the slope of the incoming signal and thereby generates proportional (to slope) sampling frequency - thus making it an intelligent circuit which is capable of employing variable sampling frequency depending on the slope of the input signal. This circuit maximizes performance and minimizes bit rate as compared to conventional sample and hold circuit whose sampling frequency has a preset value and is not capable of changing the sampling firequency when in operation. Simulation based comparison among adaptive sample and hold circuit and conventional sample and hold circuit is presented which reveals that adaptive sampler offers better performance regarding the sampling of signal with unpredictable composite frequency component and it also requires lower bit rate than conventional sample and hold circuit.