LTspice and noise analysis

After it got pointed out to me that in LTspice it was possible to tag resistor values with the 'noiseless' keyword, I reckoned it should also be possible to specify the temperature of a resistor. Indeed, it is possible to assign a value of '50 Temp=-196' to a resistor and to get the correct thermal noise contribution for that resistor in the noise analysis.

I couldn't find any mention of it in the manual, but this is very useful to me.

Jeroen Belleman

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Jeroen Belleman
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Cool. If you're motivated, you might put that in the LTspice wiki,

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
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Phil Hobbs

Adding a temperature value to a resistor is standard Spice notation. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Jim Thompson

That's quite useful indeed.

There's another trick for making a noiseless resistor - use a G element (voltage-dependent current source) and wire the control terminals to the main ones. Of course, you also have to set the value as conductance rather than resistance.

Cheers, Nikolai

Reply to
Castorp

[snip]

That's pretty-much the standard convention in original-crispy-flavored Spice.

See "NoiselessResistor.zip" on the Device Models & Subcircuits Page of my website. (I symbolize that in PSpice as a resistor with a type-tag "Noiseless".) ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Jim Thompson

Thanks Phil. The link is a nice gem.

ChesterW

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crwildey

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