by way of example only for a leakage current measurement range of 50 na to 500 na switch 27a is closed and switches 27b 27c and 27d remain opened switch 14 is closed to provide an electrical connection between the selected current sensing resistor and the i o pin 22 switch 28 then is closed for 10 u03bcs to discharge test fixture capacitance 21 and i o pin capacitance 23 to ground through resistor 29 after switch 28 is reopened a settling time of approximately 2 ms is allowed before measurement commences in the case of either a high voltage or a low voltage leakage test the voltage developed across a selected one of current sensing resistors 12a 12d appears at the input terminals of amplifier 13 and is transmitted as a ground referenced voltage to the a d converter 15 to be digitized the digitized value thereafter is accessed by the processor 16 where it is normalized to compensate for the leakage current measurement range and then compared to threshold values to determine whether the i o pin under test is within tolerances thus from equation 5 above overall settling time is reduced from approximately 11 milliseconds using the circuit of fig i of the prior art to approximately 2 milliseconds using the method and circuit of fig2 representing in excess of a five fold improvement in measurement time the combination of a precision a d voltage source 10 with 16 bit resolution use of current sensing resistors 12a 12d with tolerances of 0 1 each electronic switches 14 and 27a 27d with 25 u03c9 34 on 34 resistance and sub nanoampere typical leakage current instrumentation amplifier 13 with 0 01 typical error and a d converter 15 with 16 bit resolution provides overall.