Electrical – Problem simulating current controlled current source in LTspice

ltspice

I've been trying to simulate the following circuit in spice. (I'm plotting the voltage over R7)

enter image description here

Everything is okay, and works as expected until I change the gain of the current controlled current source to a value that's greater than 58. And I should simulate this with a value of 290. Any idea on how to fix this?

Here is another photo with the gain in 290
enter image description here

When I set the gain in 58. Spice trows the following error "spice analysis: Time step too small; initial timepoint: trouble with node n002" The node n002 is the node that connects R4 with R1. For greater values the error doesn't show up anymore but the result is the one from the picture.

Thank you for any help you can give me on this issue!

Best Answer

Behavioural sources are very versatile, but sometimes can suffer. Using the VCCS (aka G-source) should eliminate the problem. In this case, since you are only taking a current and multiply it by a constant, you can replace B2 by a VCCS like this:

replace

It takes the voltage across R3, divides it by its value (1/16k), and then multiplies it by some constant (290).

Alternately, you can either insert a zero-valued voltage source in series with R3 (let's presume it's called Vx), then use an F-source with the value Vx 290 (careful at the direction of the source, + ---> -), or replace R3 with the same zero-valued voltage source, but with Rser=16k added, same F-source.

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