Shadow bandpass filter with Q-improvement

Abstract

A new architecture of the shadow bandpass filters with the quality factor improvement is proposed. The presented idea employs external amplifiers cooperating with the classical biquad cell resulting in convenient electronic tunability of the characteristic frequency and the quality factor. The scheme obtains the benefit of the quality factor-improvement via feedback gains of the external amplifiers. The theory is verified by PSPICE simulation using 0.18 μm CMOS technology model parameters.