Continuous-Time Time-Stretched Analog-to-Digital Converter Array Implemented Using Virtual Time Gating

We demonstrate the continuous-time operation of a time-stretch analog-to-digital converter array. A continuous-time RF signal is segmented into parallel channels and each channel is stretched in time prior to digitization. The technique offers improvement in the effective input bandwidth and sampling rate of the digitizer. The implementation uses virtual time gating for interleaving segments of the continuous-time RF signal. The signal is first modulated onto a linearly chirped optical carrier and then sliced, in time, using passive optical filters. This technique obviates the need for fast switching gates. It results in minimum interchannel mismatch and in hardware efficiency since all channels are stretched using the same electro-optic modulator and the same dispersive elements.