Method and apparatus to generate a ground level of a semiconductor IC tester having a plurality of substrates

An apparatus for generating a ground level of a semiconductor IC tester having a plurality of substrate, the apparatus comprising:

• a plurality of sets of wiring means, each set of wiring means respectively on a corresponding substrate of the plurality of substrates, wherein each of the plurality of substrates supplies signals to semiconductor IC devices under test and receives signals from the semiconductor IC devices under test, each of said plurality of sets of wiring means inputting ground levels of a corresponding number of semiconductor IC devices under test;
• a plurality of first level generating means, each first level generating means respectively on a corresponding substrate of the plurality of substrates, each of the plurality of first level generating means connecting the ground levels, input by a set of said plurality of sets of wiring means, to a connecting point through resistors, and outputting a mean voltage of input reference voltages at said connecting point;
• and
• a second generating means for receiving the mean voltages which are output from said first generating means and for outputting a compound voltage of input mean voltages.

A reference voltage setting method for generating a ground level of a semiconductor IC tester having a plurality of substrates, the method comprising the steps of:

• receiving ground levels of a plurality of semiconductor IC devices under test at a respective substrate, wherein each substrate supplies signals to corresponding semiconductor IC devices under test and receives signals from the corresponding semiconductor IC devices under test;
• outputting a mean voltage of received ground levels from each of the plurality of substrates;
• and
• setting a compound voltage, of voltages which are output from the plurality of substrates, as a ground level for the semiconductor IC tester.