4. Voltage-Mode Fractional-Order Filters

This chapter presents a voltage-mode technique for realizing fractional-order filters. Low-voltage OTAs are employed as active elements. Fractional-order filters are designed with the additional benefit that different types of filter functions are realized using the same topology. As a result, the resulted filter functions are generalized. Firstly, fractional order lowpass, highpass, allpass, and bandpass filters of order α are realized the efficiency of which is verified through simulations results. In addition, fractional order lowpass, highpass, bandpass, and bandstop filters of order α + β are also given. Both designs employed MOS transistors biased in subthreshold region, offering also the benefit of low voltage operation. The design of these topologies is realized using the AMS 0.35 μm CMOS technology.