Si bipolar chip set for 10-Gb/s optical receiver

Three Si bipolar ICs, a preamplifier, a gain-controllable amplifier, and a decision circuit, have been developed for 10-Gb/s optical receivers. A dual-feedback configuration with a phase adjustment capacitor makes it possible to increase the preamplifier bandwidth up to 11.2 GHz, while still retaining flat frequency response. The gain-controllable amplifier, which utilizes a current-dividing amplifier stage, has an 11.4-GHz bandwidth with 20-dB gain variation. A master-slave D-type flip-flop is also operated as the decision circuit at 10 Gb/s. On-chip coplanar lines were applied to minimize the electrical reflection between the ICs