Study of Adjustable Gains for Control of Oscillation Frequency and Oscillation Condition in 3R-2C Oscillator

An idea of adjustable gain in order to obtain controllable features is very useful for design of tuneable oscillators. Several active elements with adjustable properties (current and voltage gain) are discussed in this paper. Three modified oscillator conceptions that are quite simple, directly electronically adjustable, providing independent control of oscillation condition and frequency were designed. Positive and negative aspects of presented method of control are discussed. Expected assumptions of adjustability are verified experimentally on one of the presented solution

A miniature tunable quadrature shadow oscillator with orthogonal control

This article presents a new design of a quadrature shadow oscillator. The oscillator is realized using one input and two outputs of a second-order filter cell together with external amplifiers in a feedback configuration. The oscillation characteristics are controlled via the external gain without disturbing the internal filter cell, following the concept of the shadow oscillator. The proposed circuit configuration is simple with a small component-count. It consists of, two voltage-different transconductance amplifiers (VDTAs) along with a couple of passive elements. The frequency of oscillation (FO) and the condition of oscillation (CO) are controlled orthogonally via the dc bias current and external gain. Moreover, with the addition of the external gain, the frequency range of oscillation can be further extended. The proposed work is verified by computer simulation with the use of 180 nm complementary metal–oxide–semiconductor (CMOS) model parameters. The simulation gives satisfactory results of two sinusoidal output signals in quadrature with some small total harmonic distortions (THD). In addition, a circuit experiment is performed using the commercial operational transconductance amplifiers LM13700 as the active components. The circuit experiment also demonstrates satisfactory outcome which confirms the validity of the proposed circuit

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

Design of RC sinusoidal oscillator based on active building blocks

Bakalárska práca je venovaná RC oscilátorom s použitím funkčných blokov a operačných zosilovačov. Na počiatku je urobený rešerš literatúry zaoberajúcej sa konštrukciou a návrhom RC oscilátorov, a použitiu rôznych funkčných blokov pri tomto návrhu. Jednotlivé funkčné bloky sú diskutované a sú vybrané rôzne zapojenia s použitím týchto blokov, ktoré sú simulované analýzou na počítači pomocou PSpice a SNAP. Je overený vznik oscilácií a vplyv jednotlivých súčiastok v zapojení. V druhej časti sú realizované vybrané zapojenia a overené teoretické poznatky na praktickej realizácii. Údaje získané z počítačovej simulácie a praktickej realizácie sú potom porovnané, a taktiež jednotlivé zapojenia sú porovnané medzi sebou.Thesis is focused on RC oscillators employing active building blocks and operational amplifiers. In the beginning, review of available literature talking about this topic is done. Different building blocks and circuits containing those blocks are picked and some of them simulated with PSpice and SNAP programs. Oscillation creation and influence of circuit components is verified. Those circuits are realized in practical application and simulation results are compared to those gained from real world circuits, also the chosen circuits are compared between each other.

Voltage Controlled Integrator and Linear Quadrature-VCO Using MMCC

A Voltage Controlled Oscillator (VCO) based on the new multiplication-mode current conveyor (MMCC) building block is presented. The oscillator is realized using a double integrator loop (DIL) where a linear frequency (fo) versus the control voltage (Vc) tuning characteristics with quadrature sinusoid signal generation in a range of 40 kHz ≤ fo≤ 700  kHz had been experimentally verified. The fo─ sensitivity is low while the frequency stability factor (Sf >>1) is high at satisfactory values of total harmonic distortion (THD ≈ 1.11%)

Sinusoidal Generator with π

This paper presents a new circuit proposal for multiphase sine-wave generation, employing two active elements and four grounded passive elements. The proposed oscillator provides four 45° phase-shifted voltage outputs. Incorporation of additional inverters for generation of eight-phase outputs is further shown. Simultaneous current outputs can also be generated with additional output stages. The compact circuit structure is studied for nonideal and parasitic effects and simulation results are given, which are in good agreement with the theory. The utility of the proposal for π/4-QPSK generation is explored as an interesting application example with supporting results

Voltage Controlled Integrator and Linear Quadrature-VCO Using MMCC

A Voltage Controlled Oscillator (VCO) based on the new multiplication-mode current conveyor (MMCC) building block is presented. The oscillator is realized using a double integrator loop (DIL) where a linear frequency (fo) versus the control voltage (Vc) tuning characteristics with quadrature sinusoid signal generation in a range of 40  kHz ≤ fo≤ 700   kHz had been experimentally verified. The fo─ sensitivity is low while the frequency stability factor (Sf >>1) is high at satisfactory values of total harmonic distortion (THD ≈ 1.11%)

Current Gain Controlled CCTA and its Application in Quadrature Oscillator and Direct Frequency Modulator

A modified conception of adjustable current conveyor transconductance amplifier (CCTA) and its interesting application in simple quadrature oscillator expandable for direct frequency modulation purposes, employing only four grounded passive elements is presented in this paper. It is quite simple solution for modern communication subsystem components. An electronic adjusting of the oscillation frequency is easily possible and control of condition of the oscillation is realized via only one grounded resistor. The characteristic equation, condition of oscillation and major parasitic influences of real active part are discussed. The verification includes PSpice simulation and measurement with the CCTA block formed by commercially available active elements

Realization of electronically tunable voltage-mode/current-mode quadrature sinusoidal oscillator using ZC-CG-CDBA

a b s t r a c t This paper presents a first of its kind canonic realization of active RC (ARC) sinusoidal oscillator with non-interactive/independent tuning laws, which simultaneously provides buffered quadrature voltage outputs and explicit quadrature current outputs. The proposed circuit is created using a new active building block, namely the Z-copy controlled-gain current differencing buffered amplifier (ZC-CG-CDBA). The circuit uses three resistors and two grounded capacitors, and provides independent/non-interactive control of the condition of oscillation (CO) and the frequency of oscillation (FO) by means of different resistors. Other advantageous features of the circuit are the inherent electronic tunability of the FO via controlling current gains of the active elements and the suitability to be employed as a low-frequency oscillator. A non-ideal analysis of the circuit is carried out and experimental results verifying the workability of the proposed circuit are included