Configurable output driver with programmable on-chip impedance supporting wide range data rates

Abstract

This paper presents a configurable driver with programmable on-chip impedance and output slew rate control scheme. The proposed output driver is implemented using 45 nm CMOS technology which can be configured as a push-pull driver or current-mode driver that can support wide range data rates. In push-pull mode, the driver can either operates in rail-to-rail swing or mid-rail swing. In current-mode, the driver can support 400 mV low voltage swing. This configurable driver provides multiple impedances of 28.6, 33.3, 40, 50, 66.7, 100 or 200 Ω that can be selected for transmit impedance and receive terminator. Besides that, the driver slew rate can be programmed to 4 V / ns or 6 V / ns for data rate below 4 Gbps. The on-chip impedance, output slew rate and voltage swing are fully digital-calibrated across process, voltage, and temperature (PVT) variations.