This regenerative feedback from the RC network is due to the ability of the capacitor to store an electric charge, (similar to the LC tank circuit). The basic RC Oscillator which is also known as a Phase-shift Oscillator, produces a sine wave output signal using regenerative feedback obtained from the resistor-capacitor (RC) ladder network. If a three-stage RC phase-shift network is connected as a feedback network between the output and input of an amplifier circuit, then the total phase shift created to produce the required regenerative feedback is: 3 x 60 o + 180 o = 360 o = 0 o as shown. We know that in an amplifier circuit either using a Bipolar Transistor or an Inverting Operational Amplifier configuration, it will produce a phase-shift of 180 o between its input and output. so four RC stages could also be used to produce the required 180 o of phase shift at the required oscillation frequency.
For example, the LM124, or the LM324, etc. Conveniently op-amp circuits are available in quad IC packages. Then the phase shift occurs in the phase difference between the individual RC stages.
RC ENGINEERING CALCULATOR SERIES
So by cascading together three such RC networks in series we can produce a total phase shift in the circuit of 180 o at the chosen frequency and this forms the bases of a “RC Oscillator” otherwise known as a Phase Shift Oscillator as the phase angle is shifted by an amount through each stage of the circuit.
0 kommentar(er)
