A 56-Gbaud PAM4 Analog Adaptive Equalizer in 90-nm BiCMOS Technology

A 56-Gbaud PAM4 analog adaptive equalizer is designed in 90-nm BiCMOS technology. The designed analog adaptive equalizer consists of an equalizer, a power detector, an error amplifier, and a charge pump. The equalizer is composed of a continuous-time linear equalizer and a low-frequency equalizer, and it is capable of simultaneously compensating for the losses of the signal at low, medium and high frequencies. The spectrum balancing scheme based on power detection is adopted to achieve adaptation. It can adaptively compensate for different attenuation channels. Simulation results demonstrate that the adaptive equalizer effectively compensates for channel losses ranging from 4.5dB to 8.5dB at 28GHz.