The voltage-mode first order universal filter using single voltage differencing differential input buffered amplifier with electronic controllability

In this research contribution, the electronically tunable first-order universal filter employing a single voltage differencing differential input buffered amplifier (VD-DIBA) (constructed from two commercially available integrated circuit (IC): the operational transconductance amplifier, IC number LT1228, and the differential voltage input buffer, IC number AD830), one capacitor and two resistors. The features of the designed first order universal filter are as follows. Three voltage-mode first-order functions, low-pass (LP), all-pass (AP) and high-pass (HP) responses are given. The natural frequency (0) of the presented configuration can be electronically adjusted by setting the DC bias current. Moreover, the voltage gain of the LP and HP filters can be controllable. The phase responses of an AP configuration can be varied from 00 to −1800 and 1800 to 00. The power supply voltages were set at ±5 . Verification of the theoretically described performances of the introduced electronically tunable universal filter was proved by the PSpice simulation and experiment

Electronically Tunable Voltage-Mode Multiphase Sinusoidal Oscillator with Low Output Impedance Nodes Employing VD-DIBAs

The multiphase sinusoidal oscillator (MSO) is useful for various electrical and electronic applications. This study aims to design an MSO employing voltage differencing differential input buffered amplifiers (VD-DIBAs). The design procedure is based on cascading the first-order low-pass filter. Each phase consists of a VD-DIBA, two resistors, and a grounded capacitor. An odd-phase system without requiring an additional amplifier. The frequency is electronically controlled through the bias current without affecting the condition. The sinewave amplitudes and the phase difference between each waveform are identical. The proposed MSO is designed to obtain three-phase waveforms (n = 3). PSPICE simulation demonstrates the performance of the proposed oscillator with 0.18 μm TSMC CMOS parameters with ±0.9 V power supply. The feasibility of the proposed MSO is also verified with experiments using the VD-DIBA constructed from commercial integrated circuits (ICs) with a ±5 V power supply. The simulated and experimental results align with theoretical predictions

A voltage-mode first order allpass filter based on VDTA

This article presents a new voltage-mode first order allpass filter (APF) employing voltage differencing transconductance amplifier (VDTA). The advantages of the circuit are that: the circuit description is very compact, consists of merely a VDTA and a capacitor: the phase shift can be electronically adjusted by current bias: it provides the lower THD of the output signal. Without any component matching conditions, the proposed circuit is very appropriate to further develop into an integrated circuit. Moreover, the proposed APF can provide the output current with high output impedance without modification of the circuit topology. The PSpice simulation results are depicted. The given results agree well with the theoretical anticipation. The maximum power consumption is 400µW at ±1.25V power supplies

Electronically and Independently Controllable Quadrature Sinusoidal Oscillator with Low Output Impedances

This work presents the quadrature si- nusoidal oscillator using two Voltage Differencing- Differential Input Buffered Amplifiers (VD-DIBAs), two resistors, and two capacitors. The VD-DIBA is an electronically controllable active building block with high input and low output impedances that can con- nect to other circuits directly without the buffers. With these distinguished features, the VD-DIBA is employed in this design. The proposed oscillator can produce two sine waves with a phase shift of 90 degrees. Over the entire tuning frequency range, the magnitude of the quadrature output voltages is constant. The pro- posed oscillator is independently adjustable in terms of frequency and oscillation condition. Moreover, the frequency of oscillation can be electronically and lin- early adjusted by the bias currents. The condition of oscillation is adjustable by resistors, R1 and R2. The performances of the proposed quadrature oscilla- tor are tested through the PSpice simulation and the experiment. In the simulation, the VD-DIBA is built from the 0.18 μm Taiwan Semiconductor Manufactur- ing Company (TSMC) CMOS process with ±0.9 V sup- ply voltages. In the experiment, the VD-DIBA is im- plemented using the commercial ICs, LM13700, and AD830 with ±5 V supply voltages. The simulated To- tal Harmonic Distortion (THD) values of the output voltages, Vo1 and Vo2 at f0 = 1.03 MHz are 1.63 % and 1.81 %, respectively. The experimental THD values of the output voltages, Vo1 and Vo2 at f0 = 536.6 kHz, are 1.43 % and 1.00 %, respectively