Re: Sinewave oscillator without gain control.

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vnck1i$295d5$1@dont-email.me...

On 24/01/2025 5:02 pm, Edward Rawde wrote:

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vmv6ac$22ufe$1@dont-email.me...

On 24/01/2025 11:14 am, Edward Rawde wrote:

Before you can make a 1kHz sinewave oscillator with constant output level and better than 120dB harmonic distortion you'll need
an
oscillator which does better than that when it passes through the required output level.

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This is obviously true. Why do you think you need to tell us about it?
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You do make me laugh sometimes Bill.
Your circuit doesn't come anywhere close to 120dB but it does depend on which simulator you ask.

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I never said it did. I was looking for comments on the way the current mirrors might screw up the waveform. I didn't get any.
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Adding a FET gain stabilizer to the circuit I posted seems to have negligible effect on the distortion.

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Then you haven't looked at the current waveform going through the the FET.
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So I'd concentrate on the oscillator distortion level rather than the gain controller contribution if I wanted to attempt better
than 120dB.

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And you'd probably better dump LTSpice 24.1 - it has been claimed that it has a serious bug. That might explain why your
simulations of my circuit run a thousand times slower for you than they do for me and a couple of other people.

24.1.1 is now available. Simulation speed of your circuit is still 25us/s.
Parasitic 22.6MHz at about 20mV pk-pk is still present.

>
--
Bill Sloman, Sydney