PURPOSE: To obtain an anti-time-limit unit which can use a (n)-multiplier with a small dynamic range easily by amplifying an input when smaller than a prescribed level, by applying it to the (n)-multiplier and then by dividing it.

CONSTITUTION: When output voltage V of i-V converter 11 is below detection value V0 of level detector 14, the output of detector 14 is "0", amplifier 12 and amplifier 13 output 10V and -V respectively, and maximum-value extractor 16 extracts 10V and applies it to square-law multiplier 17. Then, V-f converter 18 generates a pulse string equivalent to (10V)2 and in this case, decoder 21 operates to apply an output divided by 100 to counter 23. With V greater than V0, detector 14 outputs "1", and amplifier 12 -10V; and then, amplifier 13 outputs V, and extractor 16V. In this case, decoder 19 operates and divides no signal. A (n)-multiplier with a small dynamic range can therefore be used.