Analysis of reflection for high precision A/D conversion circuit

In the control system of high precision micro-displacement platform, because the high control precision is required, the design of hardware circuit should be optimized. The reflected signals are one of the important factors that influence the conversion accuracy of A/D conversion circuit. The conversion system consists of 24-bit ADS1274 A/D converter and the TMS320C6713 digital signal processor. The Hyperlynx software was used for the analysis. The reflected signal of the master clock was studied. The methods of source-series termination and far-end RC termination were adopted to weaken the reflected signals. The experiment results showed that the reflections peak could be eliminated when 100Ω terminating resistor was used at the source, or 100Ω terminating resistor and 300pF terminating capacitor were used based on the far-end RC termination. The signal integrity and digital to analog conversion accuracy of the signal were improved.