Nonideal effects in continuous-time adaptive recursive filters

Analog realizations of adaptive filters suffer from nonideal effects not normally found in their digital counterparts. The effects of two of these nonideal properties are discussed: DC offsets present in the adaptive algorithm and saturation of the programmable filter´s coefficients. A formula for estimating the effects of DC offsets and a method of introducing gain to reduce DC offset effects are provided. It is shown that different filter structures can have significantly different DC offset effects. It is also shown that although a performance surface may be unimodal, a local minimum might be created if filter coefficients become saturated