Versatile VM Universal Biquad Filter Employing OTAs and Its Application

This paper introduces a versatile configuration that uses operational transconductance amplifiers (OTAs) to realize a voltage mode (VM) filter. The proposed filter structure enables the independent control of parameters such as pole frequency (0)) and pole quality factor (Q) in an orthogonal manner, while also allowing for electronic adjustment of o) and bandwidth (BW). If an additional capacitor is added to the circuit, the filter circuit can be used as a VM and current mode (CM) third-order harmonic oscillator with two quadrature outputs. The presented mixed-mode third-order oscillator allows for the autonomous electronic control of both the frequency of oscillation (FO) and the condition of oscillation (CO). To verify the validity of the implemented circuits, SPICE simulations were conducted utilizing 0.18μm CMOS technology. The suggested circuits are well-suited for integration into a monolithic integrated circuit, as they utilize exclusively grounded capacitors.