the invention provides methods and apparatus for improving the direct current offset performance of an oversampling analog - to - digital converter , including a / d converters that include an oversampling quantizer such as a single or multi - bit δ - σ modulator , successive approximation quantizer , flash quantizer , pipelined quantizer or other suitable oversampling quantizer . the invention also relates to methods for providing a wide - band attenuation in the digital output of an a / d converter using a limited number of components .