Configurable transmitter with de-emphasis scheme supporting wide range data rates

Abstract

This paper presents a configurable driver with pro-grammable impedance, output slew rate and de-emphasis control scheme. The proposed driver is implemented using 45nm CMOS technology which can be configured as a differential push-pull driver or differential current-mode driver. In push-pull mode, the driver can operate with mid-rail swing. In current-mode, it can support 400mV and 500mV low voltage swing. Configurable driver provides multiple impedances of 50, 75 or 150Ω that can be selected for transmit impedance and receive terminator. Besides that, with slew rate control scheme, the driver slew rate can be programmed at 2-5V/ns for data rate below 4Gbps. However, slew rate control scheme is bypassed and de-emphasis control scheme is activated to gives 6dB de-emphasis to equalize ISI losses at date rate above 4Gbps and thus, improving signal integrity.