Negative Resistance - Crystal Oscillator

[FreshmanNewbie]

How to understand the term - Negative resistance in the concept of crystal oscillator?

Can someone explain me in simple terms? I've gone through different websites and articles, but I am unable to understand the concept.

Please explain in simple terms.

 

[G4BCH]

These may help you

 

[FreshmanNewbie]

These may help you

I saw all the mentioned videos before itself. But still was not clear. Could you please provide an answer in simple terms to understand?

 

[danadakk]

The basic concept of an oscillator can be looked at a viewpoint of energy
loss. If we stimulate a circuit, like an LC tank circuit, and it has no losses
then it will oscillate forever. But with losses, once we remove the stimulator
energy source, the oscillator amplitude steadily declines until it reaches 0.

Losses occur in resistive circuits. Real capacitors and inductors have resistive
parasitics in them, the dielectric in a Capacitor, the wire resistance in an inductor.
And of course skin effects in inductors.

So if we could somehow remove, or cancel out, the resistive losses in a circuit
then once stimulated that circuit would oscillate forever. Enter negative resistance.
and use it to get rid of the circuit losses.

Negative R can be accomplished with tunnel diodes, unijunction, and ....

Negative resistance - Wikipedia

en.wikipedia.org

NIC (Negative-Immittance Converter)) circuits here with OpAmps -

https://www.ti.com/lit/an/sboa093a/sboa093a.pdf

Regards, Dana.