An integrated two-parameter adaptive cable equalizer using continuous-time filters

This paper describes an analog continuous-time adaptive cable equalizer that can be implemented in a standard CMOS integrated circuit technology. The equalizer can be designed with as many poles and zeros as are necessary to compensate for cable distortion. However, only two control voltages, gain control and bandwidth control, are needed for adaptive control of the equalizer. By properly designing the relative locations of the poles and zeros, these control voltages will adjust to compensate for cable distortion and the large process and temperature tolerances on the integrated circuit. Since there are only two control voltages, the circuitry required to produce these control voltages is very simple. Also, if independent parameters of the received signal are used to develop these control voltages, such as the autocorrelation and the signal amplitude, no training is required to adapt the equalizer. Since the gain of the equalizer can be adjusted independently of the shape of the frequency response, no additional VGA is necessary.