An analog circuit includes a pair of peak-hold circuits that generate peak
signals indicating the peak values of a differential pair of input
signals, a first differencing circuit such as a transconductance
amplifier that takes the difference between the input signal values, a
second differencing circuit such as a transconductance amplifier that
takes the difference between the two peak signal values, and a combining
circuit such as a resistor circuit that additively combines the outputs
of the differencing circuits in such a way as to compensate for
direct-current offset in the input signals. Advantages of this circuit
structure include reduced power consumption and simplified implementation
in an integrated circuit. Low pass filters, capacitor discharging
circuits, and unbalanced circuit elements can be used to obtain further
advantages.