A low-noise high-gain high-speed optical receiver is fabricated in 0.13-µm SiGe BiCMOS. The transimpedance amplifier incorporating a differential common-base shunt-feedback topology features isolation to input capacitance and high transimpedance limit. Specifically, a comprehensive analytical expression of the input-referred noise current power spectral density of the transimpedance amplifier is derived and investigated, which provides insights for noise optimization. Additionally, the linearity of intermediate stages is improved by a modified variable-gain amplifier operating with automatic gain control. The measured results show a low noise level of 14.5 , 31-GHz bandwidth, and the maximum 71-dBΩ transimpedance.