A 15.5 GHz bandwidth Si bipolar preamplifier

The authors describe an extremely high performance Si bipolar preamplifier, which has a 15.5-GHz bandwidth with a transimpedance gain of 52 dBΩ. To achieve such high performance, the optimization of feedback parameters in the circuit and the realization of the 46-GHz f_max (maximum frequency of oscillation) transistor were carried out simultaneously. The circuit consists of gain and buffer stages. Employing a dual-feedback configuration in the gain stage design, the preamplifier has broadband and low-noise characteristics. The measured frequency response of the preamplifier, using the optimized circuit and the improved transistors, is shown