Pole frequency and pass-band gain tunable novel fully-differential current-mode all-pass filter

Abstract

In this paper, a new realization of a fully-differential (F-D) first-order all-pass filter (APF) operating in current mode (CM) is presented. In the proposed F-D CM APF a single adjustable current amplifier (ACA) and two current followers (CFs) with non-unity gain are used as active building blocks. Considering the input intrinsic resistance of CFs as useful active filter parameter, the proposed filter employs only a floating capacitor as external passive component. The pole frequency of the proposed resistorless circuit can be tuned via mutual change of input intrinsic resistance of CFs while the filter pass-band gain by means of gain of ACA. The theoretical results are verified by SPICE simulations, where TSMC 0.18 μm level-7 SCN018 CMOS process parameters were used.