A 10-B 225-MHZ CMOS DIGITAL-TO-ANALOG CONVERTER (DAC) WITH THRESHOLD-VOLTAGE COMPENSATED CURRENT SOURCES

Abstract

This paper describes a 10-b high-speed COMS DAC fabricated by 0.8-mu m double-poly double-metal CMOS technology. In the DAC, a new current source called the threshold-voltage compensated current source is used in the two-stage current array to reduce the linearity error caused by inevitable current variations of the current sources, In the two-stage weighted current array, only 32 master and 32 slave unit current sources are required. Thus silicon area and stray capacitance can be reduced significantly. Experimental results show that a conversion rate of 125 MHz is achievable with differential and integral linearity errors of 0.21 LSB and 0.23 LSB, respectively. The power consumption is 150 mW for a single 5-V power supply. The rise/fall time is 3 ns and the full-scale settling time to +/- 1/2 LSB is within 8 ns. The chip area is 1.8 mm x 1.0 mm.