A CMOS Current-Steering D/A Converter With Full-Swing Output Voltage and a Quaternary Driver

Abstract

This brief describes a CMOS current-steering digital-to-analog converter (D/A 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 output current cell composed of both nMOS and pMOS. First, the nMOS operates from the power supply to the half of the power supply. Second, 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 that selects the optimized current cell. A 6-bit 1-GS/s current-steering DAC has been fabricated with Dongbu 0.11-mu m 1-poly 6-metal (1P6M) CMOS technology to verify the performance of the proposed full-swing DAC. The effective chip area is 0.46 mm(2), and power consumption is about 19.1 mW. The measured results reveal that the DAC has a full-swing output signal.