chapter  5
24 Pages

AC Null Measurements

In this chapter, we examine measurement techniques that make use of sensing an ac null. These include, but are not limited to, ac operation of (resistive) Wheatstone bridges, various types of ac bridges used to measure capacitance, capacitor dissipation factor (D), inductance, inductor quality factor (Q), mutual inductance and the small signal transconductance (gm) of bipolar junction transistors (BJT) and field effect transistors. As in the case of dc null methods, ac methods are used to obtain accurate measurements of component values based on the accuracy of the bridge components.