A voltage-variable time delay element for random bit waveforms

In this work, a concept for a voltage-variable time-delay circuit element for use with low data-rate random bit waveforms is demonstrated. The circuit operates by generating pulses at every rising and falling edge of the incoming bit stream. The pulses are elongated in time by an arbitrary amount using monostable multivibrators whose RC time-constant can be controlled by an applied voltage. The outputs of the multivibrators are used to trigger a pair of flip-flops and the delayed waveform is taken at the output of an exclusive-OR gate. Experimental results show that using this mechanism, the input signal can be delayed by up to 83% of the signal period.