SIGNAL TRANSMISSION CIRCUIT

PROBLEM TO BE SOLVED: To provide a signal transmission circuit capable of preventing production of noise due to a return current with respect to a drive current. SOLUTION: A semiconductor tester T is provided with a differential output driver 1, a noninverted output terminal of the differential output driver 1 transmits a test current 1a to a receiver 2 of a semiconductor device D to be inspected through a first line 3a of a board B, a holding current 1b in reverse phase to the test current 1a is outputted from an inverted output terminal of the differential output driver 1, the holding current Ib absorbs the return current Ir going to be supplied from the semiconductor device D to be detected to the semiconductor tester T through an earth layer of the board B in response to the test current 1a, the return current Ir is stably held in a second line 3b independently of the processing of the earth layer of the board B, reflection noise due to impedance mismatching in a processing section attended with bypass of the return current Ir, radiation noise due to a formed loop of the bypass, and crosstalk to an adjacent conductor pattern are prevented so as to test the operating characteristics of the semiconductor device D to be detected with high accuracy.