A compact mixed-mode first-order universal filter based on a single voltage differencing current conveyor demonstrated accurate impedance extraction and waveform preservation in biomedical applications.
The proposed VDCC-based filter provides a compact and power-efficient solution for biomedical signal processing, including ECG acquisition and bioimpedance measurement.
This paper presents a compact mixed-mode first-order universal filter based on a single voltage differencing current conveyor (VDCC), which can function in all four possible operation modes, i.e., voltage mode (VM), trans-admittance mode (TAM), current mode (CM), and trans-impedance mode (TIM). The proposed configuration requires only two grounded resistors and one floating capacitor, which contributes to a low component count, facilitates integration, and allows for the electronic tunability of the pole frequency through the transconductance gain of the VDCC. This work also demonstrates two practical biomedical applications: an electrocardiogram (ECG) acquisition system utilizing the VM low-pass filter for noise suppression and a bioimpedance (BioZ) measurement system employing the proposed configuration-based CM oscillator circuit as a sinusoidal excitation source. The performance validation confirms the accuracy of impedance extraction and the preservation of waveforms using tissue-equivalent models. The results demonstrate that the proposed VDCC-based filter offers a compact, power-efficient, and versatile analog signal-processing solution suitable for modern biomedical instrumentation.
Moonmuang et al. (2026) studied this question. VDCC-based mixed-mode first-order universal filter was evaluated. A compact mixed-mode first-order universal filter based on a single voltage differencing current conveyor demonstrated accurate impedance extraction and waveform preservation in biomedical applications.