Rc oscillator circuit

RC oscillators are a type of feedback oscillator; they consist of an amplifying device, a transistor, vacuum tube, or op-amp, with some of its output energy fed back into its input through a network of resistors and capacitors, an RC network, to achieve positive feedback, causing it to generate an oscillating

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3. The RC Oscillator Circuit  RC Oscillators use a combination of an amplifier and an RC feedback network to produce output oscillations due to the phase shift between the stages.

4. The RC Oscillator Circuit  For an RC oscillator to sustain its oscillations indefinitely, sufficient feedback of the correct phase, that is positive (in-phase) Feedback must be provided along with the voltage gain of the single transistor amplifier being used to inject adequate loop gain into the closed-loop circuit in order to maintain oscillations allowing it to oscillates continuously at the selected frequency.

5. The RC Oscillator Circuit  However in reality it is difficult to obtain exactly 90o of phase shift for each RC stage so we must therefore use more RC stages cascaded together to obtain the required value at the oscillation frequency. The amount of actual phase shift in the circuit depends upon the values of the resistor (R) and the capacitor (C), at the chosen frequency of oscillations with the phase angle ( φ ) being

6. The RC Oscillator Circuit

7. The RC Oscillator Circuit  The oscillator itself can be tuned to operate in the frequency range of 20-100 MHz using digital control signals and this fits the current sensor implementation.

8. The RC Oscillator Circuit  RC phase shift oscillator is used for generating signals power a wide frequency ra nge. The frequency can be varied from few Hz to 200 Hz by employing one set of resistor with three capacitor ganged together to vary over a capacitance range in the 1:10 ratio.

9. The RC Oscillator Circuit  The frequency of oscillation is determined by the Barkhausen criterion, which says that the circuit will only oscillate at frequencies for which the phase shift around the feedback loop is equal to 360° (2π radians) or a multiple of 360°, and the loop gain (the amplification around the feedback loop) is equal to one.