On a family of new two‐op‐amp switched‐capacitor biquads for high‐frequency applications

Abstract

This paper presents three novel biquads derived by applying the concept of so‐called basic elements for switched‐capacitor (SC) circuits. These biquads are without continuous feedback and comprise two op‐amps. They were derived assuming a transfer function denominator of the same form as the Fleischer‐Laker type E circuit. It is shown that by a simple modification of the switching arrangement, i.e. by changing the type of the basic SC element, the effect of the amplifier finite gain on the performance of SC filters can be significantly reduced. the efficiency of this approach has been established by extensive simulation studies using the dedicated symbolic analysis program SCYMBAL. Design equations and comparison with already known biquads of this type are presented. Examples are provided to demonstrate that the proposed circuits require a low total capacitance while finite‐gain effects are considerably reduced.