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An oscillator has a tuned circuit (inductance+capacitance) to determine the frequency. When the inductor is tapped to give the required phase-shift for oscillation it is a Hartley oscillator. When the capacitance is tapped it is a Colpitts.
There are many phase shift oscillator circuits on the internet. Google search, `phase+shift+oscillator+schematics` and `phase+shift+oscillator+diagrams`. Generally, if you want to change the phase shift characteristics, you'll need to substitute some fixed resistors with variable resistors and depending where they're placed, you can either change the operating frequency or the waveform characteristics.
The output of the voltage-controlled oscillator (VCO) in a phase-locked loop (PLL) circuit is a periodic waveform, typically a sine or square wave, whose frequency is controlled by the input voltage. This voltage is derived from the phase comparator in the PLL, which adjusts the VCO frequency to match the frequency of a reference signal. As the PLL locks onto the reference signal, the VCO output frequency stabilizes, ensuring that it is phase-locked with the reference. This output can be used for various applications, including frequency synthesis and modulation.
The VCO is a special type of oscillator that has a frequency controlled by an applied voltage.The frequency of the VCO without any control signal applied is called the free running frequency.
The R-C oscillator is also called a phase shift oscillator because the R-C filter creates a phase shift from input to output. The feedback portion of the oscillator (an amplifier) then serves to pump energy back into the filter.
For small frequency of forced oscillation , the phase angle between the forced oscillator and driver is nearly zero . As the driving frequency increases the phase angle increases and is equal is PI/2 ,when both the frequencies (frequency of force and frequency of system for oscillation) are equal. For very large frequency of driver , they are out of phase.
The frequency determining components in a phase shift oscillator are the series of resistive/capacitive filters on the output of the inverting amplifier. See accompanying link.
An oscillator has a tuned circuit (inductance+capacitance) to determine the frequency. When the inductor is tapped to give the required phase-shift for oscillation it is a Hartley oscillator. When the capacitance is tapped it is a Colpitts.
RC phase shift oscillator is used to generate frequency in audio range and it is a fixed audio frequency oscillator where as wien bridge oscillator is a variable audio frequency oscillator for high frequency oscillations it is better to design wide band amplifier with LC network
One way of using a flip flop as a frequency doubler is to create an oscillator at the desired doubled frequency, and then divide by two with the flip flop, resulting in the original frequency, and then controlling the oscillator with a phase locked loop.
An amplifier can become and oscillator by adding positive feedback from the output back to the input. Positive feedback means that the phase of the signal fed back to the input is the same as the phase of the output signal. In the case of a high frequency oscillator, a tuned circuit (inductor and capacitor) or a quartz crystal in the input circuit will determine the frequency of oscillation.
Advantages: it improves frequency stability. phase modulation n demodulation is easy as compared to frequency modulation.
In an RC phase shift oscillator, oscillations are produced by the feedback network consisting of resistors and capacitors connected in a specific configuration to generate a 180-degree phase shift at the desired frequency. This phase shift, along with the inverting amplifier stage, satisfies the Barkhausen stability criterion for oscillation to occur. The loop gain of the circuit is unity and the phase shift of the feedback network is carefully controlled to ensure sustained oscillations at the desired frequency.
A Wien-bridge oscillator generates a sinusoidal waveform using an op-amp and a feedback network with both resistors and capacitors, while a phase-shift oscillator uses an RC network to introduce phase shifts in the feedback path to generate oscillations. Wien-bridge oscillators are typically used for audio frequency applications, whereas phase-shift oscillators are commonly used for higher frequency applications.
There are many phase shift oscillator circuits on the internet. Google search, `phase+shift+oscillator+schematics` and `phase+shift+oscillator+diagrams`. Generally, if you want to change the phase shift characteristics, you'll need to substitute some fixed resistors with variable resistors and depending where they're placed, you can either change the operating frequency or the waveform characteristics.
amplifier is electronic circuit which is used to increase the amplitude of the input signal without affecting its frequency and phase.
Stability of the oscillator means the how much frequency stability it have. Measure of frequency stability comes from "rate of change of phase w.r.t frequency", the more it is the more stable the oscillator is, because we know that one condition for oscillation is that the loop gain phase shift should be zero, hence if due to ckt. parameters there is some change in phase then by very little variations in frequency we can bring back the loop gain phase shift to zero. ex. is LC tank circuit which act as an osciilator at resonant frequency. Frequency stability can also be measure from quality factor, the higher it is the more stable ckt. is,Parikshit ParasherB-tech ECE, PG power engg.parikshit_parasher@yahoo.co.in