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

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