Reply-To: "Kevin Aylward"
From: "Kevin Aylward"
Subject: Re: SPICE sources
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Sat, 21 Dec 2002 18:24:28 -0000
NNTP-Posting-Date: Sat, 21 Dec 2002 18:24:47 GMT
Paul Burridge wrote:
> I'm more than a little confused about the baffling array of available
> voltage and current sources in Spice.
> In a 'real world' circuit consisting of an audio amplifier, say, one
> might have say a DC supply rail voltage of 12v, a common ground, a
> microphone input signal of 20mv p-p and an eventual output signal of
> say 10v p-p at fairly low impedance.
> Spice provides a confusing array of Vcc., Vdd., 12v+, a range of
> 'programmable' voltage sources at AC and DC (VCVS, VCCS, CCVS, CCCS)
> plus at least four different types of ground, earth, Spice ground,
> digital ground, analogue ground, etc., etc.
> Can anyone clarify what all these different sources are supposed to be
> used for and why the heck we need so many?
> And which would I choose to simulate say the audio amp?
The sources all do different things.
The main spice run types are DC, AC and TRAN(sient)
A Spice DC source is used to set the dc voltages on nodes. As a side
line a DC source also has a field to set an AC value that is use in the
AC, output against frequency "bode" type graph.
The "AC" sources e.g. "sine", "pulse", are actually use for the
transient, output against time oscilloscope type graphs.
Typically use DC sources on the power supply. If you want to do power
supply rejection plots, then you can selectable set their "AC" field to
1 Volt. St to to zero initialy while you check out the main amp
Use a "sine" source at the amp input. Set its Vpk value to say 10mv (if
lots of gain), and its frequency to say, 1Khz. This is for the transient
runs. Set its "AC" field to 1V, this will make all node plots be equal
to the gain to that node from the source in an AC run.
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.