Ac coupling circuit integrated with receiver with hybrid stable common-mode voltage generation and baseline wander compensation

Abstract

In a receiver, an AC-coupling solution uses a fully integrated circuit for simultaneously providing both baseline wander compensation and common-mode voltage generation. Usefully, an integrated capacitor is placed between the receiver input pin and the input buffer, and a high resistive impedance element is connected to the internal high-speed data node after the capacitor. An on-chip voltage generation and correction circuit is connected to the other side of the impedance element to generate a common-mode voltage, and to provide dynamic, fine adjustment for the received data voltage level. The voltage correction circuit is controlled by the feedback of data detected by the clock and data recovery unit (CDRU) of the receiver. The feedback data passes through a weighting element, wherein the amount of feedback gain is adjustable to provide a summing weight and thereby achieve a desired BLW compensation. Register bits are used to control an on-chip reference voltage generator that consists of a resistor ladder to generate the reference voltage.