| 摘要 |
PURPOSE:To enable a delay time to be measured by counting the delay time of a circuit to be measured by a counter on the basis of the ring oscillator's clock and processing a counted value like a DC current by an IC tester or the like. CONSTITUTION:Input signals (a) are inputted to circuits D1-Dn to be measured from an input signal I1 and delayed output signals, after being selected by selector 1, are inputted to an EX-NOR circuit 4. A ring oscillator 2 initiates an oscillation by control signals (c) formed from the input signals (a) and the external control signals (b) of a control terminal CT by an EX-OR circuit 3 and output clock signals (f) are inputted to a counter 7 via a delay-adjusting circuit 5 if a gate circuit 6 is opened. When the output signals (e) of the EX- NOR circuit 4 reduce to '0', the gate circuit 6 is closed and the counted number corresponding to the delay time of the circuits being measured are indicated by the counter 7.
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