Transformer based circuit for reducing emi radiation in high speed cmos serdes transmitters

Abstract

This disclosure provides methods and apparatus for processing differential signals having non-inverted and inverted signals. An example apparatus has first and second circuit arms, each arm connected to receive one of the input signals. Each arm has a post-cursor branch comprising a delay, an inverter and a series terminating resistance connected between the first input and a first circuit arm common node, and a main cursor branch comprising a buffer and a series terminating resistance connected between the first input and the first circuit arm common node. A first transformer has a primary winding connected between the first circuit arm common node and a first output and a secondary winding connected between an output of the buffer of the main cursor branch of the second arm and ground, with a capacitor and a resistor connected in series between the secondary winding and ground. A second transformer has a primary winding connected between the second circuit arm common node and a second output and a secondary winding connected between an output of the buffer of the main cursor branch of the first arm and ground, with a capacitor and a resistor connected in series between the secondary winding of the second transformer and ground.