Bilinear design of fully differential switched-capacitor ladder filters

Abstract

FulIy differential switched-eapacitor (SC) analogue blocks are shown to be suitable for implementing SC ladder filters via the bilinear transform of the corresponding analogue RLC passive prototypes. These filters become fulIy insensitive to parasitic capacitance elfects, while the interesting features of the dilferential implementation, i.e. power supply and common mode rejection ratios and dynarnic range improvements, are retained. The technique presented is useful for the exact design of wide-band SC filters, i.e. for filters with a small ratio between the dock frequency and the cut-olf frequency. As an example, the bilinear design of an 8th-order Cauer bandpass filter is given, with numerically computed results.

Switched-Capacitor Fractional-Step Butterworth Filter Design

“…1, where H i (z), i = 1, 2, 3 denotes the transfer function of a discrete-time integrator. The two most famous s-to-z transformations widely used for designing digital filters are the Bilinear and the Al-Alaoui transformations [3,12] using which a lossless integrator H a (s) = (1/τ s) would be expressed in discrete form, respectively, as…”