Design of a 32.7-GHz bandwidth AGC amplifier IC with wide dynamic range implemented in SiGe HBT

A wide-bandwidth automatic gain control (AGC) amplifier IC was developed using a self-aligned selective-epitaxial SiGe heterojunction bipolar transistor (HBT). A transimpedance load circuit was used, and its damping factor was optimized to achieve a wide bandwidth of 32.7 GHz. Capacitor peaking was introduced to the second variable-gain amplifier in order to obtain a wide gain dynamic range of 19 dB. The amplifier IC has a noise figure of 18 dB and an eye pattern at 25 Gb/s.