Digital I/F Converter Of High Precision And Small Volume

I/F converter, a current-frequency converter, is the device or equipment whichconverts the input current signal into the output frequency signal in accordance with alinear proportional relationship. The conversion accuracy of conventional I/F convertercan only reach up to10-4,some just be10-3. Its temperature drift can reach up to severalhundred ppm/℃and the volume is very large as well. The conventional I/F convertercan not meet the military requirement. This paper adopts the digital signal controllerand high-performance A/D converter to design the digital I/F converter with theaccuracy of less than5×10-5, temperature drift less than10ppm/℃with smallervolume.In this paper, I studied the key technologies of hardware of digital I/F converter,such as the power circuits, the crystal circuits, the reset circuits, the signalconditioning circuits, the A/D conversion circuits and the frequency output circuits.Using the MC56F8037digital signal controller of Freescale and ADS1259of TI, thedigital I/F converter was designed to meet the desired performance indicators bystudying the A/D conversion circuits and the frequency output circuits. Then, the paperproposes the software design scheme based on MC56F8023, which was focused onsampling, analysis and processing of the digital signal to A/D converter. In order toachieve the design goal of high precision, the paper completes the synthesis of digitalfilter and digital frequency through the acquisition of the signals with MC56F8023,and calculates the output frequency signal through the PWM or TMR tube. At the sametime, the paper also makes research and analysis of the noise encountered in theprocess of design, and designs the corresponding software and hardwareanti-interference measures.Finally, the paper makes a further test on the product. It is concluded that thedesign achieves design index according to the experimental data, verifies the feasibilityof this topic, and puts forward the research prospects in the next step of digital I/Fconverter design.