| 摘要 |
An error-detection circuit (10) employs comparison circuitry (12) to determine whether a SENSE signal is within a range indicated by XPRANGE signals. When the SENSE signal goes into or out of the indicated range, an INRANGE output of the comparison circuitry (12) moves through a predetermined voltage swing from one stable level through a threshold level to another stable level. The passage of the INRANGE signal through the threshold level is an indication to subsequent circuitry that SENSE has passed into or out of the indicated range. According to the present invention, one or other of the levels occupied by the INRANGE signal is separated from the threshold by a voltage that is only a small fraction of the swing between the two levels. As a consequence, the delay between the transition of the SENSE signal and the transition of the INRANGE output of the comparison circuitry is only a small fraction of the time required to complete the voltage swing. Systems, such as automatic testers, that employ a large number of such comparison circuits can therefore employ components that are slower and thus cost less than the component would be required in conventional circuits having the same speed.
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