Optimization of low-cost, high-speed serial data optoelectric receivers using co-disciplinary design constraints.

摘要

Plastic Optical Fiber (POF) is suitable as a communication medium for the high-data rate systems present in high-definition video cameras and TVs, gigabit Ethernet links, and short reach serial chip-to-chip, board-to-board, and (with careful design) server room rack-to-rack data links. This work examines the design of the circuits necessary to translate optical data to electrical data in such a system. An initial examination of the properties of Graded-Index Perfluorinated POF is conducted which indicates a high level of signal attenuation and less severe dispersion. With this in mind, an examination of three candidate Transimpedance Amplifier topologies is conducted using a constrained stability approach with an eye towards identifying both the topology with the lowest noise and lowest sensitivity to input capacitance in order to handle what are assumed to be loss-limited data links. The lowest noise receiver can discern ones and zeroes over longer reaches of optical fiber. Reducing the sensitivity to input capacitance allows for larger photodetectors which relax alignment tolerances and allow for lower cost system manufacturing. The application of software based-optimization routines for the classic two-pole optical receiver is compared with that for higher order systems.;An existing method of extending receiver bandwidth, bootstrapping, is extended to improve receiver performance resulting in a novel circuit called Capacitive Canceling Positive Feedback (CCPF). A new test circuit and method is developed for validating bootstrap or CCPF circuits. An analysis of the CCPF also quantifies the risks and benefits imposed by this method.;A flexible test circuit is developed in 0.25microm SiGe BiCMOS to measure the performance of the three candidate topologies while controlling for inter-chip variation due to process, voltage, and temperature. Measured results indicate that higher-order systems can be used for improved sensitivity, which is useful for extending the reach of POF based links. However, some of the practical consequences of higher order systems imply additional complexity in the design process to control for manufacturing variation and guarantee design margin.