US Patent 7155470 Variable gain integrator

A variable-gain integrator includes a variable-gain multiplier for multiplying digital input data that are input in time sequence by variable gain, an adder for adding output data from the variable multiplier to previous integration data, a clip circuit for limiting output data from the adder to a predetermined range to obtain integration data, an integration value storage device for storing the integration data obtained from the clip circuit and supplying the integration data that are stored to the adder as the previous integration data, and a fixed multiplier for multiplying the integration data obtained by the clip circuit by fixed gain.