G06G7/00—Devices in which the computing operation is performed by varying electric or magnetic quantities
G06G7/12—Arrangements for performing computing operations, e.g. operational amplifiers specially adapted therefor
G06G7/16—Arrangements for performing computing operations, e.g. operational amplifiers specially adapted therefor for multiplication or division
G06G7/161—Arrangements for performing computing operations, e.g. operational amplifiers specially adapted therefor for multiplication or division with pulse modulation, e.g. modulation of amplitude, width, frequency, phase or form