| DAC is the key device to realize the digital to analog signal conversion in the fieldof modern engineering and technology. However, the rapid development of signalprocessing equipments has put forward new requirements as high speed, highresolution, and low power consumption in DAC design. What’s more, with thedecreasing size of process dimension and higher frequency, kinds of errors occur in theDAC designs that affect the circuit performance seriously. Therefore, each aspectshould be considered comprehensively in DAC design for an optimal performance.This paper is based on a10bit200MS DAC with the process of smics0.13um. Aftercomprehensive analysis of the principle of DAC and several common structures,current-steering structure is conducted to achieve D/A converter, not only because itshigher speed and power utilization, but also its advantages of lower consumption andcost. After full comparisons of advantages and disadvantages between binary code andthermometer code, the “5+5” segment structure is adapted in this design, which issupposed to accelerate speed, reduce errors, as well as the low5bits using binarydecoding reducing the area.After determining the overall structure of the circuit, each modular of the converteris analyzed and optimized, including bias voltage generating circuit, current sourceunit and other key circuit, some errors are also overcome in the circuit design. Thedesign in this paper finally reaches the performance index as:3.3V working voltage,differential non-linearity error DNL=-0.375LSB, the integral nonlinearity errorINL=0.568LSB, SFDR equals64dB. This D/A converter is designed for the videocircuit, and is of certain practical and advanced performance. |
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