Bit-Resolution Improvement of an Optically Sampled Time-Interleaved Analog-to-Digital Converter Based on Data Averaging

In this paper, we present an experimental method demonstrating an improvement in the resolution of optically sampled time-interleaved analog-to-digital converters (ADCs) by applying a data averaging technique. We implemented two experiments for oversampling four times the bandwidth of an analog input signal using a multichannel time-interleaved arrangement. The sampling rate for each experiment was 2.08 gigasamples per second. In the first experiment, the optically sampled signal of each channel is digitized by a single ADC, whereas in the second, the signal is simultaneously digitized by four ADCs, and thereafter, the four digitized samples are averaged. A 20-dBm white-noise signal was superimposed on the input analog signal to test the implemented ADC systems. An improvement in the signal-to-noise-and-distortion ratio from 55.58 to 61.44 dB was achieved with averaging. Likewise, an improvement in the effective number of bits from 8.94 to 9.91 was achieved with averaging.