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I'm trying to modify an op amp to simulate its worst case behavior at end of life. In the common mode effect section of the LM124/NS I have the following

EOS 7 1 POLY(1) 16 49 1E-3 1

What is the function of EOS? I've been searching online for some information about what it does but to no avail.

Thanks

James
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2 Answers2

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It is a voltage dependent input offset source

The offset voltage-source, Eos, provides a supply voltage dependent input offset voltage and reflects the error voltages from the power supply rejection ratio stage, the thermal effect stage, and the noise-voltage source. Below is a diagram of the Eos polynomial-source and the effects that correspond to each term.

enter image description here

From: AN-840 Development of an Extensive SPICE Macromodel for "Current Feedback" Amplifiers

Voltage Spike
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In standard SPICE an 'E' element is a voltage-controlled voltage source. So, EOS is just a VCVS named "EOS". The standard VCVS requires four node numbers: the first two are the output nodes and the second two define the controlling voltage. The final parameter is a gain factor. In this case you may have a non-linear gain function, but the syntax is a little odd. Without more context it's hard to be sure.

Elliot Alderson
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