###### Abstract  
This study presents an electronically tunable configuration for the design of a voltage-mode (VM) biquad with four input terminals and three output terminals. The proposed circuit employs four operational transconductance amplifiers (OTAs) and two grounded capacitors. Depending on the selections of the four input voltage signals, all the standard filtering functions can be realized. The proposed configuration simultaneously provides VM inverting band-pass, non-inverting low-pass, and non-inverting band-reject filtering functions without any component-matching choices. It offers the features of a resistorless structure, high-input impedance, electronic control of the pole frequency and quality factor, and low active and passive sensitivities. The measured power dissipation of the biquad is 0.96 W under 32 mA constant output current. The measured 1 dB power gain compression point of the output inverting band-pass filter is \(-7\) dBm. The measured value of the third-order intercept point is 5.136 dBm, and the measured value of the third-order intermodulation distortion is \(-50.83\) dBc. following features: realization of two quadrature sinusoidal voltage outputs with 90\({}^{\circ}\) phase difference, independent control of frequency of oscillation (FO) and condition of oscillation (CO), electronic controllability, employment of grounded capacitors, and so on. However, the electronically controllable QQ with amplitude of output current should also be considered. The amplitude of output current can be electronically adjusted by fine-tuning the direct-current (DC) bias current (I\({}_{\text{B}}\)), which is suitable for signal processing systems and AM/ASK systems. The VM electronically tunable, high-input impedance configurations used in the design of operational transconductance amplifier and capacitor (OTA-C) biquads are worthy of study, because they are suitable for the cascade in VM operation and the fine-tuning of the deviation of conventional electronic components. OTA provides highly linear electronic controllability and has a wide tunable range of transconductance gain (g\({}_{\text{m}}\)), which is an attractive feature for circuit designers [15; 16; 17; 18; 19; 20; 21; 22; 23]. OTAs are commercially available ICs, and LT1228 from Linear Technology Corporation [24] has been widely used to implement OTA-based circuits. The transconductance of LT1228 is electronically controlled by an external DC bias current I\({}_{\text{B}}\). The OTA-C biquad does not require a resistor, so it is very suitable for IC compared to other conventional active elements. Recently, some types of electronically tunable VM OTA-based biquads have been developed [25; 26; 27; 28; 29; 30]. The circuits in [25; 26] employ six OTAs, but the proposed circuits cannot simultaneously realize LPF, inverting BPF (IBPF) and BRF responses from the same structure. In 2019, three interesting VM electronically tunable OTA-C biquads were proposed, which employ five OTAs along with two grounded capacitors [27; 28; 29]. The circuit proposed in [27] cannot use the same structure to realize LPF, IBPF, and BRF responses. The circuits proposed in [28; 29] can realize LPF, IBPF, and BRF responses with the same configuration, and can be simply converted to QQ. However, none of the circuits proposed in [25; 26; 27; 28; 29] can be transformed into an electronically controllable QQ with high-output impedance and amplitude-controllable sinusoidal current output signal. In 2020, another VM biquad using one dual-output OTA (DO-OTA), three OTAs, and two grounded capacitors was proposed [30]. The proposed circuit can realize LPF, IBPF, and BRF responses with the same configuration, and can be simply transferred to QQ. However, the proposed circuit cannot electronically control the amplitude of the high-output impedance sinusoidal current signal. The amplitude of electronically controlled high-output impedance sinusoidal current signals can be applied in AM/ASK systems.