conversion of LC oscillator to RC oscillator

[Inder7]

how can we replace L with R or C in an oscillator so that it doesnot affect the frequency range?

 

[LvW]

how can we replace L with R or C in an oscillator so that it doesnot affect the frequency range?

There are two basic methods:
1.) In a passive reference topology you simply can replace a (grounded) L by an active circuit (actively simulated inductance),
2.) You can replace the role of the inductance (NOT the inductance as a part) using one of the various active RC topologies.
For this purpose, the transfer function is necessary.

Of course, in both cases it is possible to keep the frequency characteristics.

 

[Inder7]

can you please post any circuit reg option2 that u have mentioned about replacing with an RC topology?

 

[D.A.(Tony)Stewart]

LC has higher Q than RC so is more stable.

Ceramic resonator has even higher Q

 

[LvW]

LC has higher Q than RC so is more stable.

Yes - as long as you speak about PASSIVE circuits. However, for ACTIVE RC circuits you can realize Q values as large as you want.

@Inder7: Show me the LC oscillator you have in mind - and I can you give an equivalent RC oscillator.

 

[Inder7]

what is the passive equivalent circuit of basic LR circuit i.e L can be replaced by any passive component such that the frequency remains same.

 

[FvM]

The RL high-pass can be replaced by a RC high-pass with same cut-off frequency, but only under specific conditions for the source and load impedance. As long as the external impedances are unknown, there's no solution.

A condition that can be easily solved is ZS = 0, ZL = infinity.

 

[D.A.(Tony)Stewart]

Yes - as long as you speak about PASSIVE circuits. However, for ACTIVE RC circuits you can realize Q values as large as you want.

Not quite

The LC equivalent circuit of a passive crystal or ceramic resonator is still far higher Q and stability than any Active RC Filter (Q~10,000 for AT xtal, Q>100k for SC Xtal). This is not easily achievable in RC active filters.