Susceptibility of Dual-Slope ADCs to Electromagnetic Interference: An Experimental Analysis

Dual-slope analog-to-digital converters are attractive because of its good series mode rejection ratio (SMRR), which highly attenuates interference coupled to the input signal. However, electromagnetic interference (EMI) can also affect the other ports of the converter, and this has received much less attention. This work is an experimental study on the susceptibility of dual-slope ADCs to EMI coupled to their signal, voltage reference and power supply ports. Perturbation has been directly coupled to the port (or ports) under test, while keeping the other ports interference-free. The results show that the supply port is immune to interference but the voltage reference port is quite susceptible. Further, ratiometric measurements do not cancel out interference simultaneously added to the input and voltage reference ports.