High-speed, high-resolution analogue-to-digital conversion using a hybrid electro-optic approach

A hybrid scheme for analogue-to-digital conversion (ADC) is described in which electro-optic techniques are employed to reduce the timing jitter which is a primary factor in restricting the resolution obtainable in all-electronic ADCs. The proposed system uses commercially available digitisers and optical components together with a specially designed, optically triggered sample-and-hold circuit realised in GaAs MESFET technology. A novel technique is described by means of which up to 20 parallel, interleaved ADC paths can be driven from a single mode-locked laser source. Estimated performance limits are provided.