pollostrazon
Newbie
Hello everyone,
I hope I am posting this question in the right sub-forum.
In Virtuoso (I am using spectre) I have a circuit in which I inject some charges through delta-like pulses and expect at the output a semigaussian unipolar response (I evaluate it at a time t_p). I am performing transient noise analyses (# = 300) in order to get the input-referred noise in terms of charge (Equivalent Noise Charge, in electrons) at t_p through a formula which is basically based on the Signal-to-Noise Ratio. For reference when SNR -> inf, ENC -> 0 e- .
My issue is that when I compare the results obtained for a transient noise in which every possible noise source is activated (noise contribution list is not set) and those obtained through single transient noise analyses in which I enable a block at a time (noise contribution list set to "on" for the block I want to get info about), they don't add up. I'll provide a numeric example so as to make my statement clearer. Let's say that transient noise gives me 250 e- at the input, then I perform the transient noise with single block contribution activated (preamplifier, shaper, biases) and, summing them, I get 170 e-; summing them in quadrature doesn't work too. My question is: where are the 80 e- missing? I made sure to perform one transient noise for each single block, so no block contribution is missing in the sum.
Transient noise analysis is set to conservative, noisefmax = 1G, noisefmin = 1, noiseseed = VAR("ITERATION") (I set this value to parallelise transient noise analyses).
Hope everything is clear and specified to an acceptable degree.
Thanks in advance for the help.
I hope I am posting this question in the right sub-forum.
In Virtuoso (I am using spectre) I have a circuit in which I inject some charges through delta-like pulses and expect at the output a semigaussian unipolar response (I evaluate it at a time t_p). I am performing transient noise analyses (# = 300) in order to get the input-referred noise in terms of charge (Equivalent Noise Charge, in electrons) at t_p through a formula which is basically based on the Signal-to-Noise Ratio. For reference when SNR -> inf, ENC -> 0 e- .
My issue is that when I compare the results obtained for a transient noise in which every possible noise source is activated (noise contribution list is not set) and those obtained through single transient noise analyses in which I enable a block at a time (noise contribution list set to "on" for the block I want to get info about), they don't add up. I'll provide a numeric example so as to make my statement clearer. Let's say that transient noise gives me 250 e- at the input, then I perform the transient noise with single block contribution activated (preamplifier, shaper, biases) and, summing them, I get 170 e-; summing them in quadrature doesn't work too. My question is: where are the 80 e- missing? I made sure to perform one transient noise for each single block, so no block contribution is missing in the sum.
Transient noise analysis is set to conservative, noisefmax = 1G, noisefmin = 1, noiseseed = VAR("ITERATION") (I set this value to parallelise transient noise analyses).
Hope everything is clear and specified to an acceptable degree.
Thanks in advance for the help.