Abstract: A analog-to-digital conversion apparatus and method for mobile communication devices are disclosed by the present invention. Because the conventional CMOS process does not allow for high order anti-aliasing circuits to be fabricated with digital circuits on the same chip, a new apparatus had to be developed to use low order anti-aliasing filters for the analog-to-digital conversion. The apparatus of the present invention includes a low order anti-aliasing circuit, a delta-sigma converter, and post-conversion filters. The post conversion filters include a decimation circuit, a droop correction filter, and an offset adjust circuit. In this implementation, a low order analog anti-aliasing filter can be used along with a delta-sigma converter and post-conversion filters to eliminate the need for high order analog anti-aliasing filters. Another aspect of the present invention is the duplication of the circuits to process the incoming signals. The duplicate circuit is fed a null signal to process the noise only.