.8-bit High Speed D / A Converter Design

The purpose of this project is to realize a design of an 8 Bit high-speed digital-analog converter (DAC).In order to deal with the physical signal of nature, we must use analog-digital converter (ADC) and digital-analog converter. ADC and DAC are applied in wide field, such as computer ,television, communication, military affairs and digital signal processing(DSP).Development of these fields depends on the advancement of ADC and DAC. DAC is a part of ADC, so development of ADC relies on the progress of DAC.DAC has been the one of problems, which restrict the development of the computer, communication and DSP. It has been a key, which solves the speed and precision of signal processing.In this paper, design and fabrication program of an eight Bit DAC are described in details. First of all, the mode of input and output is confirmed to be parallel-input and complementary current-output, which is adapt to the require of high-speed. After comparing with many structure of DAC, the segmented current-steering architecture is decided. And differential current switch and segmented current technique are used in it.The DAC consists of reference amplifier, current switch, bias network and precision resistance network, so it is analog circuit. Based the characteristic of the circuit, we simulate it with Pspice software. The layout of the circuit is designed and drawn with the tool of Candence. Process experimentation of the circuit is carried with in a 3 u m bipolar process of Sichuan Institute of Solid-State Circuits. Dual-In Line package mode is used in package .The 1C has sixteen pins.Finally, 8 Bit DAC is fabricated, in which settling-time is form 105ns to 117ns and differential linearity is + 1/2LSB.It can be interfaced directly with TTL, CMOS, PMOS and others. It is useful in many electronic fields, such as data acquisition, data processing systems.