A hands-on approach to differential circuit measurements

Electronic engineering is showing a definite trend towards differential circuits. However, most measurement instruments are single-ended. Consequently, engineering graduates often lack the skills to perform correct differential measurements. This paper describes the theoretical background, development and limitations of three experiments that help students to gain insight into differential measurements and the origin and consequences of a low common-mode rejection ratio. The experiments require only common equipment and suit both electrical and non-electrical engineering students.