Negative resistance in oscillator using positive feedback

Positive feedback is a method of providing feedback in an electronic circuit where the output signal is fed back to the input with the same polarity. This type of feedback is used in oscillator circuits to sustain oscillations. Negative resistance is an important characteristic of an oscillator circuit, and it can be achieved using positive feedback. The following are the ways of accomplishing negative resistance in oscillator using positive feedback:

1. Introduction to negative resistance

Negative resistance is a phenomenon where the current flowing through a circuit increases as the voltage across it decreases. In other words, negative resistance is a property of a device that allows it to draw more current as the voltage across it decreases. This characteristic is opposite to that of a resistor, which draws less current as the voltage across it decreases.

2. Positive feedback

Positive feedback is a method of providing feedback in an electronic circuit where the output signal is fed back to the input with the same polarity. This type of feedback is used in oscillator circuits to sustain oscillations. Positive feedback causes the output signal to reinforce the input signal, resulting in an increase in the amplitude of the output signal. This increase in amplitude can be used to compensate for any losses in the circuit and sustain oscillations.

3. Oscillator circuit

An oscillator circuit is a circuit that generates an AC signal without any external input. It consists of an amplifying element, a feedback network, and a resonant circuit. The feedback network provides positive feedback to sustain the oscillations, while the resonant circuit determines the frequency of the oscillations.

4. Negative resistance using positive feedback

Negative resistance can be achieved in an oscillator circuit using positive feedback. This can be done by introducing an active device, such as a transistor or an operational amplifier, in the feedback network. The active device provides gain to the circuit, which can be used to compensate for any losses in the circuit. The gain provided by the active device can also be used to introduce negative resistance into the circuit.

Conclusion

In conclusion, negative resistance in oscillator circuits can be achieved using positive feedback. This can be done by introducing an active device in the feedback network to provide gain to the circuit. The gain provided by the active device can be used to compensate for any losses in the circuit and sustain the oscillations.