PULSE WIDTH MEASURING DEVICE AND TIME DIFFERENCE MEASURING DEVICE, AND IC TEST DEVICE

PURPOSE:To dispense with the use of a high frequency clock, and moreover to promptly and accurately measure a pulse width or a time difference between two arbitrary pulses. CONSTITUTION:At every time when a pulse 120 corresponding to a time difference is passed through pulse width decreasing circuits 102 to 104 in order, the pulse 120 is turned into a state where its pulse width is decreased as much as a fixed pulse width. On the other hand, detecting circuits 105 to 107 for the existence of the minimum allowable width pulse detect whether or not the width of each of output pulses 121 to 123 issued from the circuits 102 to 104 is more than the minimum allowable width, and the width of the pulse 120 can be highly accurately measured by an encoder 108 from the number of the steps of the pulse width decreasing circuits having output the output pulses 121 to 123 at those being in width above the minimum allowable width.