# RC Phase shift oscillator

#### Binus01

Joined Jul 12, 2022
3
Hi team,
I am looking for help design an RC phase shift oscillator with a frequency of 400MHz. The simulation on proteus is not showing any waveform. I would appreciate if anyone could assist .Thanks

#### AlbertHall

Joined Jun 4, 2014
12,269
Welcome to AAC, @Binus01
Please show a schematic of your circuit otherwise we would only be guessing.

#### Binus01

Joined Jul 12, 2022
3
Welcome to AAC, @Binus01
Please show a schematic of your circuit otherwise we would only be guessing.
Okay thanks , below attached is the picture of the trials

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#### LvW

Joined Jun 13, 2013
1,669
Disregarding the mentioned frequency of 400MHz - you should re-check the shown circuit (in particular the function of resistor R1).
More than that - what is the purpose of the shown input signal source?

#### Ian0

Joined Aug 7, 2020
8,400
Hi team,
I am looking for help design an RC phase shift oscillator with a frequency of 400MHz. The simulation on proteus is not showing any waveform. I would appreciate if anyone could assist .Thanks
400MHz is optimistic for an LM358.
Component values suggest about 15kHz.

#### Binus01

Joined Jul 12, 2022
3
400MHz is optimistic for an LM358.
Component values suggest about 15kHz.
What size of the op amp would do

#### Ian0

Joined Aug 7, 2020
8,400
What size of the op amp would do
Generally, op-amps don’t do 400MHz.

For a phase shift oscillator to work, the amplifier must have gain of at least 20dB at the oscillator frequency, and very little phase shift of its own. So you need something with a gain-bandwidth product of >10GHz.
Good luck.

You should also learn how to calculate the component values, as you are out by more than four orders of magnitude.
https://en.wikipedia.org/wiki/Phase-shift_oscillator

#### crutschow

Joined Mar 14, 2008
32,915
At that frequency a Colpitts or Hartley oscillator design may be more appropriate.

#### Ian0

Joined Aug 7, 2020
8,400
At that frequency a Colpitts or Hartley oscillator design may be more appropriate.
At that frequency, any other oscillator would be more appropriate, except, perhaps, a 555.
At the nearby 418MHz popular remote control frequency, SAW (surface acoustic wave) oscillators are popular.

#### Papabravo

Joined Feb 24, 2006
20,394
At that frequency a Colpitts or Hartley oscillator design may be more appropriate.
Even then special techniques in design and construction may be required.

#### BobTPH

Joined Jun 5, 2013
7,554

#### Audioguru again

Joined Oct 21, 2019
6,161
Your circuit has some serious problems.
Here is a phase shift oscillator that works fine:

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