Design considerations for loop filters in continuous-time adaptive equalizers

Continuous-time adaptive equalization at the receiver of high-speed serial communications systems is a commonly used solution to overcome the degradation of the signal caused by channel bandwidth limitations. The design of an adaptive equalizer is carried out either in the time domain using a comparator or in the frequency domain using the spectrum balancing technique. This work shows that these two approaches are equivalent and can be understood in the frequency domain only. Furthermore, it uses a unified theoretical description to formulate design criteria for the practical implementation of continuous-time adaptive equalizers.