Re: Can anyone explain this effect?

From: Leon Heller (leon_heller_at_hotmail.com)
Date: 09/15/04 

Date: Wed, 15 Sep 2004 21:39:27 +0100

"Paul Burridge" <pb@notthisbit.osiris1.co.uk> wrote in message
news:rrtgk0tv5dnktlfsjcc1dhs88lobl29ld9@4ax.com...
>
> Hi guys,
>
> May I direct your attention to the following:
>
> http://www.burridge8333.fsbusiness.co.uk/triangle.gif
>
> Where you will find a very simple common-source FET stage that gives
> some rather odd results when simulated. It feeds a 0.5mV AC sine
> voltage of 10Khz to the gate of the FET. The output is a reasonable
> replication of the input signal shape, but upon removing the inductor
> (which I had to insert to prevent this problem) the output turns into
> a perfect triangle wave. This gross distortion of the input signal
> only seems to happen at very small input levels, but nevertheless, I
> can think of nothing in the real world that might explain it. Could it
> be some sort of peculiarity with the intricacies of spice signal
> sources of which I am ignorant? If not, how is this sine-to-triangle
> conversion taking place?

It works fine for me, using Pulsonix SPICE.

Leon