Reply-To: "Kevin Aylward"
From: "Kevin Aylward"
Subject: Re: SPICE model of XTAL
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Mon, 9 Dec 2002 18:22:33 -0000
NNTP-Posting-Date: Mon, 09 Dec 2002 18:22:41 GMT
Paul Burridge wrote:
> On Mon, 9 Dec 2002 13:58:31 -0000, "Kevin Aylward"
> opined thusly:
>> Which one?
> I'm currently trying out b^2 Spice Pro by Beige Bag s/ware. Not with
> very much success, so far though. For a supposedly professional
> package it seems to have quite a lot of incomplete models in the parts
> library. :-( If I'd bought the standard or student version, I could
> understand it. But I didn't to avoid precisely this sort of scenario.
I'm a bit frugal in my own supplied models, but if its a generic type
part that I have missed I try and add it in if someone requests it. In
fact I recently added in a generic current mode controller and a voltage
mode controller for smps.
Most of the time having 20,000 models in a library is a waste of time as
most don't get used.
>> Spice itself does not have an "inbuilt" xtal, or xtal oscillator, so
>> its not a fault of the software. Oscillators are constructed in
>> spice by making a .subckt model. This model will have a model for
>> the xtal itself and one for the amplifier. The xtal model portion
>> will consist of a series LCR and a parallel c. The amplifier could
>> be done in may ways.
> Well there's definitely a generic xtal in the parts list.
> thought one could have entered a value for resonant frequency, but
> strangely it appears not.
But this is based on a .subckt, therefore, by default, in most spices
there wont be a specific dialog set-up for it.
Although this might sound a bit biased, you really do learn a lot by
making up your own models. Its just the same as designing any other
circuit. The idea being that if you can't design a little model with
ideal components, you not likely to have much luck with designing a real
circuit. The models for the controllers I mentioned above were done by
drawing and debugging a schematic version in SuperSpice, then using a
button press to convert those schematics to a standard spice .subckt
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.