The VDDDA in multifunction filterwith mutually independent Q and ω0 control feature

The paper focuses on the application possibilities of the newly presented voltage differencing active building block called voltage differencing differential difference amplifier - VDDDA. Using this active element, a multifunction frequency filter is designed featuring the possibility of mutually independent control of quality factor Q and characteristic frequency ω₀ by means of active elements. The structure of the filter is based on the idea of the Akerberg-Mossberg (AM) filter, i.e. the integrators in the structure are always realized only by two active elements. This fact results in better phase compensation for the filter. Compared to the AM opamp based filter, the newly proposed structure features high-impedance inputs, low-impedance output, and all basic frequency responses. The performance of the proposed structure has been verified by SPICE simulations using the TSMC 0.18 μm level-7 SCN018 CMOS process parameters with ±0.9 V supply voltage.