Current-Mode Fractional-Order Filters
This chapter presents a current-mode technique for realizing fractional-order filters, where low-voltage current mirrors are employed as active elements. A novel topology of a current mirror, which is able to realize large time-constants is introduced. The proposed topology is then used for realizing transfer functions of fractional-order differentiator, lossless and lossy integrator of order α, and fractional-order filters of any type (i.e., FLPF, FHPF, FBPF, FBSF) of order 1 + α, which are realized by the same core, and therefore, they can be considered as generalized filter structures. The performance of the aforementioned circuits has been evaluated using the Analog Design Environment of the Cadence software and the Design kit provided by the TSMC 180 nm CMOS process.
KeywordsFractional-order filters Low-voltage circuits Current-mode filters Current-mirrors