Abstract: One embodiment of the present invention is directed to an apparatus for reducing errors affecting the intercept of a logarithmic device, the apparatus including a first switching device coupled to an input of the logarithmic device. The first switching device for switches the input of the logarithmic device between an input signal and a reference signal. The apparatus further includes a polarity switching device coupled to an output of the logarithmic device. The polarity switching device is configured to switch the polarity of an output signal of the logarithmic device when the logarithmic device is receiving one of the input signal and the reference signal. The apparatus further includes a low pass filter coupled to the polarity switching device.

Abstract: A method and circuit to eliminate an offset noise, which may be produced at or near DC (zero Hertz) in an analog, linear multiplier, is described. An input signal is chopped (converted to another frequency) by a first chopper, shifting a frequency of the input signal such that the multiplier output signal is shifted away from DC. An output signal of the multiplier is subsequently chopped again by a second chopper employing the same chopping frequency as the first chopper. This converts a frequency of the output signal to a desired frequency at or near DC. The double chopping also shifts the offset noise produced by the multiplier to a frequency, that is higher than the frequency of the output signal. The offset noise can then be removed by a low-pass filter leaving the output signal without the offset noise.