| In modern society, with the development of microelectronic technology, electronic products are increasingly rich in kinds. Digital to analog converter (DAC) in microelectronics technology is an indispensable electronics module. Its function is to transfer signal processed by digital circuit to analog output. In the field of industrial control, some electronic systems working in different environments require a variable control voltage. The accuracy of control voltage generated by DAC determines the overall performance of the control system. So the studies on high precision DAC become an important research topic.This paper designed a digital-analog converter chip with negative voltage output, which is applied for industrial control and uses a total of three structuresThe design of three types of DAC was analyzed and their respective implementation structures and the error sources affecting the performance were studied. The realization of12bit DAC design was given with the method of segmented folding method. In the design of DAC full-chip, the implementations circuit of reference source Vref, digital interface SPI, buffer amplifier of the output, a power-on reset POR and electric level conversion circuit is studied. Each of the module is simulated to ensure that it does not affect the performance of the DAC. After the completion of the circuits of each module, the whole system is simulated and the layout is finished, when designing the layout some special attention is payed for matching and the isolation of interference.According to the actual environment where the chip is used, we tested the chip. Consequently, resistor type DAC is selected as the final structure. The tests done for electrical properties of the chip show that in the environment where10%of the supply voltage is shifted and the ambient temperature ranged from-55to85, the DNL of DAC was less than2LSB, the INL was less than4LSB and the settling time of full scale is less than lus which meet the requirements. |
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