High-quality factor asymmetric-slope band-pass filters: a fractional-order capacitor approach

This study presents new techniques for implementing continuous-time second-order band-pass filters with high-quality factors and asymmetric slopes. The techniques are centred around the realisation of two non-conventional transfer functions which include the non-integer-order Laplacian operator sα; 0<α<1. Four main possible circuit realisations; one based on a frequency-dependent negative resistor (FDNR), another based on an inductor and two based on multiple amplifier biquads (MABs) are given and verified using Spice and experimentally for both transfer functions. In addition, a field programmable analogue array (FPAA) realisation is tested and verified. Last but not least, a possible realisation using current conveyors is also given, tested and verified.