Abstract: An combined approach for reducing the errors in the notch frequency f(z), in the pole frequency f(p), in the quality factor Q(p) and in the amplitude H(p) at the pole frequency of switched-capacitor low-pass notch biquads is presented. At first, the conventional integrators in the biquads are replaced with gain- and offset-compensated integrators. Subsequently, the errors Δfz/fz, Δfp/fp, ΔQp/Qp and ΔHp/Hp are minimized by modifying the values of the integrating capacitances and of the appropriately chosen zero-forming and pole-forming capacitances. The effectiveness of this approach is demonstrated by designing two low-pass notch biquad topologies which realize the same transfer function.
Keywords: Filters, gaincompensation, offsetcompensation, operational amplifiers, switched-capacitor integrators.