Circuits with time-varying parameters (modulators, frequency-changers and parametric amplifiers)

It is shown that the theory of circuits with time-varying parameters may be presented in a manner sufficiently simple for undergraduate instruction, and that the basic conceptions of modulators with complex impedances and of parametric amplifiers may thus be made clear. Moreover, the treatment is general in nature, and so brings out the similarities and differences between circuits with time-varying resistance and those with time-varying inductance and capacitance. Non-linear effects are also touched upon