An inductor-less ultra-compact transimpedance amplifier for 30 Gbps in 28 nm CMOS with high energy-efficiency

A transimpedace amplifier (TIA) for optical links with data rate (DR) of up to 30 Gbps is presented. The design uses several bandwidth and gain enhancement techniques such as regulated common-gate, transimpedance boosting by current injection, transimpedance/transadmittance feedback and active inductor. The design is realized in a 28 nm CMOS technology. Since the circuit does not use any passive planar inductor or other special radio frequency component the area is only 0.4 × 10^-3 mm² and is to our knowledge the smallest TIA reported to date in the 30 Gbps DR range. The measured bandwidth is 22 GHz with a power consumption of only 2 mW resulting in an energy efficiency of 0.067 pJ/bit. The gain of the TIA is approximately 43 dBΩ with only one stage. The TIA is suitable to be integrated into complex CMOS VLSI systems as an alternative to copper-based short-distance interconnects. An output buffer for 50 Ω matching was added to the output, allowing the measurement.