14-bit D/A Converter Design Based On CMOS Technology

Digital to analog converter is an important interface between digital system and analog system.When applied in the field of industrial ultrasound,instrumentation,medical imaging,military defense and communication receiver,it not only requires low power consumption,small chip area,but also D/A conversion accuracy to reach 14 bit.So the accuracy of 14 bit DAC high speed and low power consumption has become a focus of research.This paper based on the Cadence software platform by SMIC 0.18?m CMOS technology,a 14 bit digital to analog converter with high conversion rate,low power consumption and small area is designed..It mainly includes:the resistance network,bandgap voltage reference,data selection switch circuit and operational amplifier circuit.In this paper,bandgap reference using operational amplifier structure,self cascode structure,compared with the classical circuit using the operational amplifier voltage,the number of transistors is reduced by half,which not only reduces the power consumption of the circuit,and the power supply rejection ratio is improved significantly;compared with traditional operational amplifier and two stage amplifier,resistor compensation circuit in place with the MOS,the amplifier gain is increased to 107dB,so as to optimize the linearity;conversion network resistance value than the traditional small resistance network is nearly five times,thereby reducing the power consumption and the establishment time,improve the conversion rate of frequency.By the simulation of the14-bits DAC,the simulation results as follow:when power supply voltage is 1.8V,the differential nonlinearitu error is 0.42LSB.When the output in full swing,the setup time is 12.3ns.The power dissipation is 40.45?W,the conversion rate is 0.044V/ns.The whole layout area is 0.016mm~2,and it passed DRC and LVS verification.