High-speed opto-electronic transient waveform digitiser

In many military systems there is an increasing pressure to gather more and more data on the environment surrounding a platform or weapon. Analogue to digital converters are required because the data gathered from most sensors is analogue and the form required for computers and digital signal processing is digital. Current ultrawideband radar and electronic warfare applications may require data to be digitised at 10 GSa/s with 8-bit resolution or more. This is far in excess of the performance of current commercial monolithic electronic ADCs. In fact, the ADC is often a limiting factor in the overall system performance. This paper describes a transient waveform digitiser that uses an optical technique to convert a single (electrical) signal into a series of time delayed copies. Traditional repetitive sampling techniques can then be used to achieve a high overall sampling rate. Results are presented for a prototype digitiser operating at 16 GSa/s with 8-bit resolution.