Patent attributes
In a circuit, as the bridge resistance of one side of a Wheatstone bridge circuit, a distortion gauge (fixed reference resistance) of which variation caused by environmental conditions is suppressed and a sample having a resistance component ΔR varied by the environmental conditions are connected in series. A constant bridge input voltage Ei is applied from a constant-voltage power supply to the Wheatstone bridge circuit, a bridge output voltage Eo corresponding to resistance variation of the sample is input to a dynamic distortion amplifier, and a carrier wave signal of a predetermined frequency is output. A measured resistance computing unit samples peak levels of the carrier wave signal output from the dynamic distortion amplifier so as to detect the bridge output voltage Eo, and calculates the resistance of the sample based on the detected bridge output voltage.
