Demonstration of an optoelectronic 4-bit analog-to-digital converter using a thyristor smart comparator

An optoelectronic analog-to-digital converter (ADC) approach with 4-bit operation is demonstrated based on the combination of HFETs and an optoelectronic thyristor. The optoelectronic thyristor implements the comparator function and generates both optical digital and electrical output. The basic comparator function is combined with HFET differential amplifiers to form a smart comparator (SC) which becomes a building block that may be cascaded N times to form an N-bit ADC. In this paper, one SC is used in a feedback loop with the appropriate clocking to achieve 4-bit operation. When the optoelectronic thyristor and the HFET amplifiers are fabricated as a monolithic integrated circuit, multi-GB/s operation is expected. (C) 2000 Elsevier Science B.V. All rights reserved.