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Versatile Tunable Voltage-Mode Biquadratic Filter and Its Application in Quadrature Oscillator
San-Fu Wang1, Hua-Pin Chen2, Yitsen Ku3
1Department of Electronic Engineering, National Chin-Yi University of Technology, Taichung 41170, Taiwan. sf_wang@ncut.edu.tw.
Sensors (Basel, Switzerland)
|May 24, 2019
Summary
This study introduces a novel, electronically tunable, resistorless biquadratic filter using operational transconductance amplifiers (OTAs). This versatile circuit can function as a five-input/single-output or single-input/three-output filter, and can be reconfigured into a quadrature oscillator.
Area of Science:
- Electronics Engineering
- Analog Signal Processing
- Circuit Design
Background:
- Operational Transconductance Amplifiers (OTAs) are fundamental active components in analog circuit design.
- Biquadratic filters are essential for realizing complex frequency response characteristics.
- Tunable filters are crucial for adaptive signal processing applications.
Purpose of the Study:
- To present a novel, versatile, and electronically tunable voltage-mode biquadratic filter.
- To demonstrate the filter's capability to be reconfigured into a quadrature oscillator.
- To achieve independent tuning of frequency and quality factor without resistors.
Main Methods:
- Utilized five single-ended output OTAs and two grounded capacitors for the filter topology.
- Explored two distinct operational modes: five-input/single-output and single-input/three-output.
- Verified theoretical analysis through circuit simulations (OrCAD PSpice) and experimental measurements.
Main Results:
- Achieved resistorless and electronically tunable biquadratic filtering with various responses (lowpass, bandpass, highpass, bandreject, allpass).
- Demonstrated simultaneous realization of multiple filtering responses in the single-input/three-output mode.
- Confirmed independent electronic tunability of oscillation condition and frequency for the quadrature oscillator configuration.
Conclusions:
- The proposed OTA-based biquadratic filter offers high versatility and independent tunability.
- The resistorless and grounded capacitor design simplifies practical implementation.
- The circuit's adaptability for both filtering and oscillation applications makes it suitable for advanced analog signal processing systems.
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