Abstract: A pair of a first and a second R-C integrating circuits connected in series. A first switch S.sub.1 supplies a first combined voltage E.sub.1 +E.sub.3 of a first positive threshold voltage E.sub.1 and a positive initial set up voltage E.sub.3 to a first capacitor in the first R-C circuit, and a second switch S.sub.2 supplies a second capacitor with a second combined voltage of a second positive threshold voltage E.sub.2 with a negative initial set up voltage -E.sub.4. The switches S.sub.1 and S.sub.2 are closed before the input of the signal to be measured. The switches are opened after the input of the signal. A first comparator compares a first discharged voltage output from the first capacitor and the first threshold voltage E.sub.1, and a second comparator compares a second discharged voltage output from the second capacitor and the second threshold voltage E.sub.2.

Abstract: A plug board for testing integrated circuits includes a plurality of sockets for receiving the terminals of an integrated circuit to be tested, a plurality of contacting terminals arranged in an annular layout and electrically connected to the sockets, an annular grounding belt electrically connected to the contacting terminals and adapted to be grounded, and a drive system adapted to rotate the plug board about the center of the contacting terminals.