0.5 V Universal Filter Based on Multiple-Input FDDAs

This brief presents a universal filter based on multiple-input fully differential difference amplifier (FDDA) that is suitable for extremely low-power low-voltage applications. The filter employs three FDDAs, eight resistors, four capacitors and can provide low-pass, band-pass, high-pass, band-stop and all-pass voltage responses. Thanks to the utilization of the multiple-input MOS transistor technique, one differential pair with an arbitrary number of inputs is required for constructing the FDDA. Therefore, unlike the previously published FDDA-based universal filters, the proposed filter has the simplest CMOS structure with less power consumption than those already published in the literature. The filter operates with 0.5 V, consumes 740 nW and exhibits rail-to-rail input common mode range. The dynamic range of the BP filter is 73 dB for 1% third intermodulation distortion. The circuit was designed in Cadence/Spectre environment using the TSMC 0.18 µm CMOS process design kit, and the simulation results confirm the advantages of the proposed filter.