RC Phase-shift Oscillator Research Articles

Studying the operation of MOSFET RC-phase shift oscillator under different environmental conditions

The present work was mainly concerned with studying the operation of RC-phase shift oscillator based on MOSFET type 2N6660 under the influence of different temperature levels ranging from room temperature (25 °C) up-to135 °C and gamma-irradiation up-to 3.5 kGy. In this concern, both the static (I–V) characteristic curves of MOSFET devices and the output signal of the proposed oscillator were recorded under ascending levels of both temperature and gamma-irradiation. From which, it is clearly shown that the drain current was decreased from 0.22 A, measured at 25 °C, down to 0.163 A, at 135 °C. On the other hand, its value was increased up-to 0.49 A, whenever the device was exposed to gamma-rays dose of 3.5 kGy. Considering RC-phase shift oscillator, the oscillation frequency and output pk-pk voltage were decreased whenever MOSFET device exposed to gamma radiation by ratio 54.9 and 91%, respectively. While, whenever MOSFET device exposed to temperature the previously mentioned parameters were shown to be decreased by ratio 2.07 and 46.2%.

NUMERICAL AND EXPERIMENTAL ANALYSIS OF EMI-INDUCED NOISE IN RC PHASE SHIFT OSCILLATOR

Electromagnetic interference (EMI) has an adverse efiect on the performance of electronic circuit communication systems. This study derives a series of equations to analyze the efiects of the EMI induced in a conducting wire on the noise spectrum of a RC Phase Shift Oscillator (RCPSO). It is shown that the extent to which EMI afiects the RCPSO depends on the interference power, interference frequency, induced power, output resistance of oscillator circuit, and parasitic capacitance. Speciflcally, higher EMI frequencies and amplitudes have a greater efiect on the RCPSO output. The results presented in this study are in good agreement with those predicted from general EMI theory.

The loop-gain modulator: A new class of linear amplitude modulators

A new type of class A modulator is introduced. This circuit, called the loop-gain modulator, exhibits a high degree of modulation linearity even for an index of modulation approaching unity. The concept is based on modifying the loop-gain of an oscillator with the modulating voltage. An analysis is done for the RC phase shift oscillator, although the method can be used with any oscillator. Experimental results that verify this analysis are reported.

Steady state analysis of oscillatory circuits with harmonic components by volterra series

AbstractChua and Tang reported a method based on the Volterra series to find the amplitude and frequency of the unknown fundamental wave component of a steady‐state oscillation resembling a sinusoidal wave generated in a self‐starting oscillation circuit. In the present paper, the method is used to find the higher‐order terms so that the harmonic components generated from the term related to the determination of the fundamental component can be found relatively easily. Formulas for the determination of such quantities are derived. Next, this method is used for the analysis of the van der Pol oscillator for which the detailed nature of the solution is available. The validity and the limitation of the application are studied. From the results, it is shown that reasonably accurate solutions can be derived for an oscillation waveform close to a sinusoid as well as a distorted one containing harmonic components. In this method there is no need to derive the differential equation for the oscillator. Insteady, only the algebraic equation found from the circuit diagram must be solved. Finally, this characteristic is used for analysis of an RC phase shift oscillator.

The distributed RC variable-frequency phase-shift oscillator

Methods of realising the voltage-controlled variable-frequency distributed RC phase-shift oscillator in integrated form are considered. A metal-oxide-semiconductor capacitor structure in which the metal is a nichrome resistor is specified. Two methods of varying the oscillation frequency are considered. The first uses the voltage-variable capacitance of the MOS structure. A simplified theory predicts the transfer characteristics well. The available frequency range as an oscillator is small because of the limited capacitance range of the devices used. However a frequency-voltage characteristic linear to better than 0.05% from 4.85 MHz to 5.1 MHz is observed. A very much wider frequency range is expected with improved devices. A second method of varying oscillation frequency uses a shunt varactor diode. The theory presented gives good agreement with measurements of transfer characteristics and predicts an attenuation near to 21 dB at 180° phase shift over a useful frequency range. This is also confirmed experimentally. The performance as an oscillator is limited in frequency by the non-ideal amplifiers used.

Micropowered Water Activated Switch Using Capacitive Sensing

A water activated switch using a capacitance transducer as one element of an RC phase shift oscillator is described. When water enters a sensing chamber, its electrical capacitance increases, driving the circuit into oscillation. The oscillations are detected and used to trigger an external circuit. Designed around a micropowered integrated circuit, the special advantages of this system are low standby current and freedom from false triggering caused by water spray or mist. The device works equally well for salt or fresh water.

A Wide-Range Variable-Frequency Phase-Shift Oscillator

An RC phase-shift oscillator, whose frequency of oscillation can be varied from a minimum value to a value as high as desired, theoretically up to infinity, by varying a single resistor in the phase-shift network, is described.

Stable linear reaction oscillator

The linear chemical reaction system, described in a preceding paper, which showed undamped oscillations under certain conditions is reviewed in the light of the complete set of eigenvalues. Since one eigenvalue is found to be positive real, the system is extremely sensitive to the correct choice of initial conditions. A minute change in the “circuitry” of the system has the effect that all eigenvalues can be moved into the left complex half-plane (real part negative) including the imaginary axis. Thus, within a wide range, an arbitrarily chosen set of initial conditions will yield undamped sinusoidal oscillations after a short period of transient behaviour. Besides, the minimum number of steps in the feedback path is now three instead of five, making the original analogy to the electronic RC phase-shift oscillator even closer.

Undamped sinusoidal oscillations in linear chemical reaction systems

It is shown both by mathematical analysis and by computer simulation that it is possible to design a chemical analogue to the well-known electronic RC phase-shift oscillator. The system consists of (1) a chemical reaction whose rate is linearly dependent on the concentration of a catalyst, and (2) a chain of successive first order reactions with the product of part 1 as input and the catalyst as output. Initial substrates considered as pools with constant concentrations and certain relations between the parameters of the system (rate constants, initial conditions, etc.) obeyed, the system shows undamped purely sinusoidal oscillations in the reaction rates and in the concentrations of the intermediates. The main characteristics of the system are that there is a closed loop in the flux of information, but an open chain in the flux of matter, the catalyst, which at the same time is one of the products, being destroyed by a first-order reaction and in addition by a reaction with constant rate.

The two-section RC phase-shift oscillator

The two-section RC phase-shift oscillator

The two-section RC phase-shift oscillator

The two-section RC phase-shift oscillator

A new analysis of the transistor phase-shift oscillator

The relationship between transistor parameters and circuit characteristics of an RC phase-shift oscillator is analysed by flow-graph and root-locus techniques. Exact formulae and approximations for the starting frequencies of three- and four-section RC phase-shift oscillators are derived. Prediction of the operating frequency for a given current gain is presented graphically and compared with experimental results.

Transistorized RC phase-shift power oscillator

A transistorized RC phase-shift oscillator is very similar to the electron tube circuit. Two important differences are: 1) A transistor possesses active phase-shift elements which can be utilized as part of the total phase shift; 2) large current capabilities of the transistor make it possible to obtain significant power at reasonable resistance values. The small-signal analysis given herein is based upon a hybrid-π transistor equivalent circuit which includes the active phase-shift elements of the transistor. Data are given for some operating circuits. Frequency modulation of the transistorized phase-shift oscillator can be readily carried out by modulating the transistor active phase-shift elements.