Re: The low distortion oscillator problem

On 7/02/2025 4:06 am, Edward Rawde wrote:

"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:isg8qj15nkgl5cg41lgt4h4oav3bbgej2n@4ax.com...

On Thu, 6 Feb 2025 03:58:59 +1100, Bill Sloman <bill.sloman@ieee.org>
wrote:
>

There have been quite a few postings about 1kHz low distortion sine wave
oscillators.
>
The problem is that if you want a get stable output from a sine wave
oscillator you have to add a non-linear element to control the gain
around the oscillating circuit.
>

>
You don't.
>

 There are plenty of examples out there claiming to be a stable output sinewave oscillator, with no obvious non-linear element.
 https://www.google.ca/search?q=sinewave+oscillator&udm=2
 But a quick simulation of one of them (a 2kHz oscillator) shows that it's not even 40dB down at 4kHz.
 Maybe follow that with a Chebychev low pass filter with a zero in the stop band at 4kHz.

It's obviously clipping on the supply rail. It's pretty subtle clipping - the top of the sine wave is sightly, but perceptibly, flatter that the bottom, but it does stick out like a sore thumb in the Fourier transform.
--
Bill Sloman, Sydney