An energy- and area-efficient limiting amplifier with interleaving feedback for 25 Gb/s optical receiver

A 25 Gb/s energy efficient limiting amplifier (LA) with active feedback is presented. To obtain high energy efficiency, the inverter-based amplifier is employed, and the use of interleaving feedback in the four stages enhances the bandwidth of LA core while maintaining a flat frequency response within the 3 dB bandwidth. Fabricated in SMIC 55 nm CMOS technology, the measurement results demonstrate that the proposed LA achieves a bandwidth of 18.5 GHz with a gain of 36.8 dB, and consumes only 17.3mWat 1.5Vsupply voltage, corresponding to an energy efficiency of 0.69 pJ/bit at 25 Gb/s operation. Due to the absence of passive inductors and capacitors as well as compact structure, the LA core area is only 0.0008 mm(2).