Low-voltage fully cascadable resistorless transadmittance-mode all-pass filter

Abstract

This paper presents a new realization of a first-order transadmittance-mode (TAM) all-pass filter (APF). In the proposed mixed-mode APF a simple transconductor, inverting voltage buffer, and unity-gain current follower are used as active building blocks. Considering the input intrinsic resistance of current follower as useful active filter parameter, the proposed TAM APF employs only a floating capacitor as external passive component. Hence, it is a resistorless circuit. In addition, due to high-impendence voltage input and high-impedance of output current terminal, it is fully cascadable filter realization. SPICE simulation results are included to support the theory. In the design the PTM 90 nm level-7 CMOS process BSIM3v3 parameters with low (±0.5 V) DC voltages were used.