Geoffrey_Coram
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Ben - Pushing Eugene's response a little further: you could implement it with an LR circuit on an internal node, but I think you can use the laplace_nd operator, also. Depending on the simulator and how it implements Laplace transforms, this might not be computationally efficient, though. x = white_noise(1); I(g,s) <+ laplace_nd(x, {0, sqrt(A)}, {sqrt(B), sqrt(C)});
The Laplace transform filter I've defined is H(s) = 0 + sqrt(A) s / (sqrt(B) + sqrt(C) s) but you're only interested in its response on the imaginary axis, ie, s = 0 + jw = j 2 pi f. (The mos11 equations actually have 2 pi f, so I'll leave this in terms of w.) The output power spectral density for the current noise between gate and source is then |H(s)|^2 times the power spectral density of x (which is 1), so you get Sig = |H(s)|^2 = sqrt(A) jw / (sqrt(B) + sqrt(C) jw) * sqrt(A) (-jw) / (sqrt(B) + sqrt(C)(-jw)) = A w^2 / (B + C w^2)
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