Realization of SIMO biquad filters and quadrature sinusoidal oscillators using OTRAs

In this communication, two single-input multiple-output (SIMO) type biquad filters employing operational transresistance amplifiers (OTRAs) have been presented. Various parameters of the proposed filter circuits viz. pole frequency (ɷ), pole quality factor (Q) and the gain are independently controllable. The proposed filter configurations can also be converted into low frequency oscillators with fully uncoupled control of condition of oscillation and frequency of oscillation with quadrature output voltages. The active and passive sensitivities of the proposed circuits have been found to be small. SPICE simulation results and experimental validation of the proposed circuits employing OTRAs realized with AD844 type CFOAs have also been presented.

New Electronically Tunable Third Order Filters and Dual Mode Sinusoidal Oscillator Using VDTAs and Grounded Capacitors

This study introduces a third order filter and a third order oscillator configuration. Both the circuits use two voltage difference transconductance amplifiers (VDTAs) and three grounded capacitors. By selecting the input and output terminals properly, current mode and transimpedance mode low-pass and band-pass filters can be obtained without component matching conditions. The natural frequency (ω0) can be tuned electronically. The oscillator circuit provides voltage and current outputs explicitly. The condition of oscillation (CO) and the frequency of oscillation (FO) can be adjusted orthogonally and electronically. The workability of the configurations is judged using TSMC CMOS 0.18 μm technology parameter as well as commercially available LM13700 integrated circuits (ICs). The simulation results show that: for ±0.9V power supply, the power consumption is 1.08 mW for both the configurations, while total harmonic distortions (THDs) are less than 2.06% and 2.17% for the filter and oscillator configurations, respectively.

Isomorphic Circuits of Independent Amplitude Tunable Voltage-Mode Bandpass Filters and Quadrature Sinusoidal Oscillators

This paper presents isomorphic circuits of voltage-mode (VM) non-inverting bandpass filters (NBPFs) and VM quadrature sinusoidal oscillators (QSOs) with independent amplitude control functionality. The proposed VM NBPFs and VM QSOs exhibit low-output impedance and independent amplitude control, which are important for easily cascading the VM operation and independent control of the amplitude gain. The proposed isomorphic circuits employ three LT1228 commercial integrated circuits (ICs), two grounded capacitors, two grounded resistors and one floating resistor. The use of grounded capacitors is beneficial for the implementation of the IC. Both NBPFs have a high-input impedance and have a wide range of independent amplitude tunable passband gain without affecting the quality factor (Q) and center frequency (fo). The Q and fo parameters of the proposed NBPFs are orthogonal tunability. By feeding back each input signal to the output response of the NBPF, two VM fully uncoupled QSOs are also proposed. The proposed VM fully uncoupled QSOs have two quadrature sinusoidal waveforms with two low-output impedances and one independent amplitude tunable sinusoidal waveform. The frequency of oscillation (FO) and the condition of oscillation (CO) are fully uncoupled and controlled electronically. The performances of the proposed isomorphic circuits have been tested with a ±5 volt power supply and are demonstrated by experimental measurements which confirm the theoretical assumptions.

Condition of phase angle for a new VDGA-based multiphase variable phase shift oscillator from 0o to 90o

A novel interesting type of variable phase angle voltage mode oscillator using modern building block has been presented in this paper. The new proposed oscillator configuration which uses four voltage differencing gain amplifier (VDGA) and two grounded capacitors can generate two sinusoidal signals that change out of phase by 0 to 90 degree. It has four floating and explicit voltage mode outputs where every two outputs have the same phase. The circuit is characterized by (i) the condition of phase angle of the oscillation (PO) (this concept is introduced for the first time in this paper) can be tuned electronically (ii) the gain of the floating outputs can be controlled independently (iii) it provides electronic control of condition of oscillation (CO) and independent control of frequency of oscillation (FO). The Total Harmonic Distortion (THD) of the output waveforms was obtained and the results were reasonability values (less than 4.5%). The non-ideal analysis and simulation results are investigated and confirmed the theoretical analysis based upon VDGAs implementable in 0.35μm CMOS technology. Simulation results include time response and frequency response outputs generated by using the PSPICE program.

Electronically Tunable Mixed Mode Quadrature Oscillator Using DX-MOCCII

A new electronically tunable quadrature oscillator is presented using a biquad band pass filter. The new band pass filter is designed using two dual X second-generation multi-output current conveyors (DX-MOCCIIs), two grounded capacitors, two grounded resistors and one NMOS transistor working in the triode region. It is used to design a four-phase voltage and three-phase current output quadrature oscillator simultaneously. The frequency of the oscillator can be tuned externally through the MOS gate voltage without affecting the condition of oscillation. The phase noise, frequency stability and nonideality analysis are given. The functionality of the oscillator circuit has been confirmed by SPICE simulation and also hardware realization using commercially available IC AD844.

Current/Voltage Controlled Quadrature Sinusoidal Oscillators for Phase Sensitive Detection Using Commercially Available IC

This paper presents the quadrature sinusoidal oscillators for a phase sensitive detection (PSD) system. The proposed oscillators are design by using the commercially available ICs (LT1228). The core oscillator consists of three LT1228s: two grounded capacitors and one resistor. By adding four resistors without the requirement of additional active devices, the amplitudes of two quadrature waveforms become adjustable. The quadrature output nodes are of low impedance, which can be connected to the impedance sensor or other circuits in a phase sensitive detection system without the need of buffer devices. The amplitudes of the quadrature waveform are equal during the frequency of oscillation (FO) tuning. The frequency of oscillation is electronically and linearly controlled by bias current or voltage without affecting the condition of oscillation (CO). Furthermore, the condition of oscillation is electronically controlled without affecting the frequency of oscillation. The performances of the proposed oscillators are experimentally tested with ±5 voltage power supplies. The frequency of the proposed sinusoidal oscillator can be tuned from 8.21 kHz to 1117.51 kHz. The relative frequency error is lower than 3.12% and the relative phase error is lower than 2.96%. The total harmonic distortion is lower than −38 dB (1.259%). The voltage gain of the quadrature waveforms can be tuned from 1.97 to 15.92. The measurement results demonstrate that the proposed oscillators work in a wide frequency range and it is a suitable choice for an instrument-off-the-shelf device

Voltage Differencing Gain Amplifier-Based Sinusoidal Quadrature Oscillator Using Only Two Grounded Capacitors

Background: This article describes the circuit construction of the sinusoidal quadrature oscillator using two Voltage Differencing Gain Amplifiers (VDGAs) as active devices. Methods: Since the presented oscillator circuit uses only two external grounded capacitors as passive elements, it is quite suitable for monolithic integration point of view. The condition of oscillation and the frequency of oscillation are non-interactive, and can be controlled electronically by tuning two separate biasing currents. Non-ideal analysis and sensitivity performance are also discussed. Results: The feasibility of the designed oscillator is justified by the PSPICE simulation results based on TSMC 0.35-µm CMOS process parameters. Conclusion: The effects of the VDGA non-idealities on the proposed circuit are also provided, and the computer simulations based on TSMC 0.35-mm CMOS model parameters are included to evaluate the performance of the circuit.

Current-Controlled Current-Mode Quadrature Oscillator Using Translinear Current Conveyors

In this paper, a current-mode quadrature oscillator using second-generation current conveyors (CCIIs) is presented. The proposed oscillator consists of two CCIIs, two grounded capacitors and two grounded resistors. The circuit is suitable for integrated circuit implementation by using grounded capacitors. In addition, a new current-controlled current-mode quadrature oscillator using two current controlled second generation current conveyors (CCCIIs) and two grounded capacitors can be obtained by replacing CCIIs and resistors series at X terminals with CCCIIs. The condition of oscillation and frequency of oscillation can be orthogonally controlled. The frequency of oscillation can be controlled by grounded resistors and external bias currents. The proposed circuits have been simulated by SPICE simulations. The simulation results are confirmed the proposed theory.

New Voltage-Mode Sinusoidal Oscillators Using VDIBAs

This paper presents two new voltage-mode sinusoidal oscillators based on voltage differencing inverting buffered amplifier (VDIBA). The first proposed circuit exhibits independent and electronic control of oscillation condition by using the bias current of the VDIBA. The proposed configuration contains only single VDIBA, two grounded capacitors and two resistors, which are the least number of active components and the minimum number of passive components necessary for realizing voltage-mode oscillator topology. The second proposed circuit exhibits independent and electronic control on the condition of oscillation without affecting the oscillation frequency by adjusting the separate bias currents of the VDIBAs. The proposed configuration contains two VDIBAs, two grounded capacitors and one resistor, which can provide four quadrature voltage outputs simultaneously. Both proposed circuits enjoy only two grounded capacitors, which are suitable for monolithic integration. HSpice simulations and experimental results are included to confirm the theoretical analysis.

Realization Approach for Sinusoidal Signal Generation and Circuit with Easy Control

A new approach for realizing sinusoidal signal with quadrature property is proposed, which employs simple analog building blocks and facilitates easy tuning of the oscillation frequency, through a gain factor. The proposed approach is used for realizing a novel quadrature oscillator circuit, which requires three current feedback operational amplifiers and passive components. The proposed circuit provides outputs at low impedance terminals, and benefits from easy control over the frequency of oscillation (FO), which depends on resistive ratio, rather than absolute resistor values. The frequency control is also independent of the condition of oscillation (CO). The nonideal effects and the parasitic studies are presented. The verification of the proposed realization scheme for quadrature oscillators and the new circuit is carried out through both simulation studies and experimental results, using the commercially available chips.