Catching an Electronic Pulse With Varactors

We present an implementation of arbitrary-waveform absorption with time-varying circuit elements. We begin by deriving a general approach, given a parallel or series RLC termination to a transmission line, for the time-varying capacitance function required to completely absorb an incident signal. We present a physical realization of this time-varying capacitance using varactor diodes, including measurement results, and comment on future improvements and implementations for time-variant varactor circuits.