Abstract: A circuit relies on the natural time constant presented to a pulse input signal which drops the signal level to a very low value “zero state,” less than 0.1 percent of the peak value, before the next pulse arrives. The signal is amplified with a low-noise, wideband, AC-coupled amplifier and split into two equal signals. One of the signals is delayed relative to the other by a fraction of the repetition period and then both signals are input to separate very wideband track-and-hold circuits. Output signals from the track-and-hold circuits are amplified, subtracted and applied to the input of an analog-to-digital converter. The track-and-hold circuits are clocked in such a way that one track-and-hold holds the value at the peak of the signal and the other track-and-hold holds the value at the baseline of the signal, the point when the signal has decayed to the zero state.

Abstract: A method can be for use in a photonic analog to digital converter, a first optical signal and a radio frequency signal. The method modulates the first optical signal based on the radio frequency signal, quantizes one or more of phase, quadrature, and amplitude coordinates of the modulated signal, and provides the quantized coordinates to one or more electronic analog to digital converters.

Abstract: A photonic analog to digital converter includes one or more modulators configured to receive a first optical signal and a radio frequency signal. The one or more modulators is configured to modulate the first optical signal based on the radio frequency signal. The converter also includes circuitry configured to independently quantize one or more of phase, quadrature, and amplitude coordinates of the modulated signal. The circuitry provides the quantized coordinates to one or more electronic analog to digital converters.