Low-voltage Current-Mode Analog Filter Using Current Differencing Transconductance Amplifier

This paper presents a new low-voltage, low-power current-mode active filter with three inputs and seven outputs. The design is implemented using three current differencing transconductance amplifiers (CDTAs) and two grounded capacitors. The proposed current-mode filter can realize both non-inverting and inverting transfer functions for low-pass, band-pass, high-pass, band-stop, and all-pass filters within a single topology. It features low input impedance, high output impedance, and eliminates issues related to inverting inputs, multiple input signals, and input matching conditions. The natural frequency of the filters can be electronically controlled. The bulk-driven MOS transistor technique is employed in the CDTA to enable operation at low supply voltages, with transistors operating in the subthreshold region to achieve low power consumption. This version of the CDTA also incorporates a z-copy terminal, which enhances its versatility for current-mode circuit applications. Simulations conducted in Cadence Virtuoso using 0.18 μm CMOS technology from TSMC validate the effectiveness of the proposed filter and CDTA. The filter operates with a supply voltage of 0.45 V, consumes 1.039 μW of power, achieves a total harmonic distortion (THD) of 1% with a 14 nA amplitude input sine wave signal, and provides a dynamic range of 65.9 dB. The Monte Carlo analysis, along with process, temperature, and voltage corner analyses, confirms the robustness of the design.