An inhibit circuit which produces an inhibit signal when a variation in a
power supply potential is detected includes a comparator having a
negative input connected to a generator producing a reference potential
and a positive input connected to an output of a first image circuit
producing a first potential that is an image of the power supply
potential. The first image circuit includes a diode and a circuit for the
production of a reference current parallel-connected between a common
point to which the power supply potential is applied and an output of the
first image circuit connected to the positive input of the comparator.
The circuit has particular utility in portable integrated circuits with
very low consumption when idle such as in mobile telephony.