الفهرس 
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Abstract
In this thesis, several techniques have been developed for the analyses of linear systems containing periodically operated switches. We start by an exact method based on state space description of these systems to get a closed from expression for the output due to a single frequency input. However, it has been shown that this approach is computationaly complicated and time consuming. To improve the speed of evaluation of the fundamental transfer function of these systems, the distributed frequency domain approach is introduced. This method is used for analysing a special circuit configuration which consists of a linear lumped analogue system with input and output switches operating at different rates (in harmonic relation). In this approach the distributed frequency domain and the system’s Z-parameters are used to get the steady state response of the system up to half the sampling rate. Finally, two time domain based methods are proposed to describe the behaviour of these systems up to half the sampling rate. The first method is called the impulse response method. In this method, a closed from expression for the laplace transform of the output due to a single impulse input is derive. Along the jw axes this form yields the system’s transfer function up to half the sampling rate. This method is much faster than using the exact method. However, it still needs some matrix manipulation. In the second method, a further speed improvement in the evaluation of the fundamental transfer function is made by using a computer program to reduce the output time response due to a single impulse input applied at the beginning of the active phase, into a rational function form (in z-domain). It has been shown that, this method reduce computation costs drastically. Finally, an extension of the idea of periodically operated switches is made to accommodate digital systems application, in what is called multi rate digital systems. As an example of these applications a communication.