A simple predistortion technique for active filters

This article deals with the predistortion of active- filters to compensate for the accountable nonideal performance of the operational amplifiers (OA\´s). In particular, the predistortion attempts to compensate the effect of the finite gain-bandwidth product (GB) of the OA\´s. This method can be used for circuits consisting of any number of OA\´s. The method realizes not only the specified pole frequency and pole factor as some other methods do, but also the exact gain requirement at a specified frequency of importance. In specific examples, it will also be shown how to choose the parameters in the network to attain minimum pole sensitivity due to the GB\´s of the OA\´s, while predistortion is achieved. This method is simple enough that the design of most second-order active- filters can be implemented in a programmable calculator.