This paper presents our recent studies on CMOS front-end circuits for high speed optical links. The circuit topologies of both transimpedance amplifier (TIA) and modulator driver (MD) are discussed for achieving wideband operation in PAM-4 modulation using advanced CMOS technology. Also, issues of integration of the circuits with silicon photonic devices such as the Ge-on-Si photo diode (PD) and silicon modulator are addressed for high performance silicon-based transceiver front-end of optical link.