A HIGH-FREQUENCY ACTIVE RC-FILTER BASED ON POLE SENSITIVITY TO THE GBPRODUCT

If a general purpose operational amplifier is treated as an ideal mode l in constructing an active RC filter, the filter performance begins t o degrade at several kHz, depending on the frequency realized and Q. T he main cause is the finite GB product; the second order poles, the ou tput resistance and the input capacitance may be secondary factors. In this paper, a previously reported filter, using a non-inverting ampli fier and compensating only for the GB product, is treated. A design me thod is proposed to reduce the pole sensitivity to the GB product in a ddition to compensating for the effects due to imperfection of the sec ond order poles, output resistance, and input capacitance. Concerning the design sequence, a design method is first shown that reduces the p ole sensitivity to the GB product. The two types of circuit parameters are adjusted so that the amplitude errors due to the above imperfecti ons are minimized. By means of the present method, the degradation of filter characteristics due to these imperfections can be prevented to a great extent. This is shown by configuration examples and experiment al examples. (C) 1998 Scripta Technica.