US Patent 7184901 Digitizing electrical measurement system

A scheme, including a microcomputer, for measuring physical quantities of a passive component. A programmable sinusoidal signal generator is used for generating the test analog sinusoidal signal. An analog-to-digital conversion system has a first node coupled to the first node of a serial three terminals network, a second node coupled to a second node of a voltage follower or buffer, and a third node coupled to the microcomputer for delivering a second and a third digital sinusoidal signal to determine a physical quantity of a DUT (device under test) by the microcomputer based on the second, third digital sinusoidal signal and the resistance of the reference resistor.