A Full-Swing CMOS Current Steering DAC with an Adaptive Cell and a Quaternary Driver

Abstract

This paper describes a CMOS current steering digital-to-analog converter (DAC) with a full-swing output signal. Generally, a normal current steering DAC cannot have a full swing output signal, because conventional DACs have an inevitable voltage drop at the output current cell. In order to improve the drawbacks, we propose a new scheme of quaternary driver and an adaptive output current cell composed of both nMOS and pMOS. As well as the nMOS operates from the power supply to the half of the power supply, the pMOS operates independently from the half of the power supply to the ground voltage. Then, the final output voltage is obtained through a multiplexer that is driven by a quaternary driver which selects the optimized current cell. A 6-bit 1GS/s current steering DAC has been fabricated with Dongbu 0.11um 1-poly 6-metal CMOS technology to verify the performance of the proposed full-swing DAC. The effective chip area is 0.46mm2 and power consumption is about 19.1mW. The measured results reveal that the DAC has a full swing output signal.