From: Terry Pinnell
Newsgroups: sci.electronics.design,sci.electronics.cad
Subject: Re: Transistor amplifiers v. frequency in SPICE
Date: Fri, 17 Jan 2003 17:34:42 +0000
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Paul Burridge wrote:
>On Fri, 17 Jan 2003 11:17:56 +0000, Terry Pinnell
> opined thusly:
>
>>Supplementing previous replies, I've posted a summary of my results at
>>http://www.terrypin.dial.pipex.com/Images/PaulAmp1.gif
>
>Well I'm grateful that you've taken the trouble to simulate this
>circuit, Terry. I have to say, though, that the results you obtained
>were as unlikely in real life as mine have been! The major obstacle
>being that you're showing a peak output of several times supply rail
>volts, which shouldn't happen with a purely resistive load such as
>this.
Eh, why do you think that? I suspect you've misinterpreted the Bode
Analysis scale. For example, '300.0 V' means a gain of 300, not an
output. Reference is 1 V.
>However, I've modified my circuit to be *exactly* the same as
>yours now (why the 1M load?)
As I said earlier, it was an assumption "...(with my arbitrary
assumption of 1M load)". What load are you using?
> and *still* get a big, fat *zero* volts
>out right across the band under test. In other circuits I've
>simulated, I get the kind of plots I'd expect outside of SPICEWORLD
>(tm), so there's obviously nothing wrong with my AC sweep function. It
>must be something unique to this circuit.
Not sure I follow that. Results seem as expected to me.
Terry Pinnell
Hobbyist, West Sussex, UK