Comparator circuit

A comparator circuit used in a semiconductor device testing apparatus in which a predetermined test pattern signal is applied to a semiconductor device under test, the voltage value of an response signal read out of the semiconductor device under test is compared with a comparison voltage supplied from a comparison voltage source to determine whether the response signal is larger than or smaller than the comparison voltage, and the output of the determination result is supplied to a logical comparing circuit to inspect whether the response of the semiconductor device under test is correct or not,

• said comparator circuit comprising a voltage comparator having two input terminals one of which is supplied with a response signal of a semiconductor device under test through a voltage dividing circuit, and the other of which is supplied with the comparison voltage from said comparison voltage source, said voltage dividing circuit being comprising a resistance component that exists in the input circuit for the voltage comparator and a terminating resistor, and determining whether the voltage value of the response signal supplied to the one input terminal is larger than or smaller than the comparison voltage, and further comprising:
• compensating means provided between said comparison voltage source and the other input terminal of said voltage comparator, for changing the comparison voltage by an amount equivalent to a voltage change of the response signal produced in said voltage dividing circuit.