Design and Implementation of SAR ADC

Abstract

The successive approximation register analog to digital converter (SAR ADC) technique is not yet mature in China mainly because of the imperfect analog module of the SAR ADC. The purpose of this design was to optimize the analog module by designing and making a 8-bit 1MHz SAR ADC and testing a 12-bit SAR ADC theoretically and by simulation. The design of the 1MHz SAR DAC, which consists of analog circuit and digital circuit, was designed according to the positive design method and the specific standard. And the ADC circuit was designed according to the sub-module layout. By the time the project design was finished, its hardware which was made of discrete components by welding printed circuit board (PCB) was debugged. The hardware’s physical properties were analyzed by using a SAR DAC test platform created in LabVIEW8.6 interfaced with data acquisition cards. This designed SAR ADC can be applied to sensor interface, data acquisition system, portable test instrument, low power control system and some aspects of communication. Its absolute average error is about 1% in the laboratory tests which meet the expectations of high accuracy requirement. When it was used in the ropeway project of agriculture engineering project, it reached a good accuracy of 91.5%. It is recommended that PCB automatic routing function be used to reduce the error and interference in the further study from the tests result.