Massively parallel time-stretched analog-to-digital converter

Time interleaving is an effective method for increasing the sampling rate of electronic analog-to-digital converters (ADCs). The main artifact of time-interleaved ADC (TI-ADC) is caused by mismatches between different sub-ADC channels. The mismatches include mismatches in gain, bandwidth, and frequency response. The ultimate achievable bandwidth of the TI-ADC is limited by the bandwidth of the sample-and-hold (S/H). Currently, the bandwidth of S/H constructed using electronic transistor is limited to the lower tens of GHz range. To increase the bandwidth of ADC into the upper tens of GHz range and beyond, incorporating photonic preprocessor becomes the natural choice. In this paper, we present our efforts on the implementation of a massively parallel TI-ADC with photonic preprocessor. In our system, the input signal is sampled using a mode-lock laser. The sampled pulses are stretched in optical fiber until they are long enough to be sampled by a massive array of 2 Giga-samples per second (GS/s) electronic ADC.