Patent ID: 7221170
Filing Date: 2007-05-22
Classification: G01R,G11C

Abstract:
1. A semiconductor test circuit in a semiconductor device to measure a state of at least one electrical signal of the semiconductor device, the semiconductor test circuit comprising: a first signal selecting unit comprising a first operational amplifier that either outputs a first electrical signal received from a first terminal in an active state or provides a high impedance state to a pad connected to a second terminal in an inactive state, in response to a first control signal; a second signal selecting unit comprising a second operational amplifier that either outputs a second electrical signal received from a first terminal in an active state or provides a high impedance state to the pad connected to a second terminal in an inactive state, in response to a second control signal; and an Nth signal selecting unit comprising an Nth operational amplifier that either outputs an Nth electrical signal received from a first terminal in an active state or provides a high impedance state to the pad connected to the second terminal in an inactive state, in response to an Nth control signal, where N is an integer greater than two, wherein a voltage level of the first electrical signal at the first terminal of the first operational amplifier is isolated from a voltage at the pad, wherein a voltage level of the second electrical signal at the first terminal of the second operational amplifier is isolated from the voltage at the pad, and wherein a voltage level of the Nth electrical signal at the first terminal of the Nth operational amplifier is isolated from the voltage at the pad.