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LTSpice - Conversion dB to V in .ac analysis, .meas, error log

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New Member

I do some calculations in LTSpice by using directive .meas in ac analysis. However, LTSpice shows results in dB (in error log) and I can't do simple conversion dB to V (dB=20log(V/V0)), because when I try to do this (conversion) LTSpice just returns the result of expression in dB. For example, I have a measure, which value is 50 dB, then I divide it by 20 (for the conversion from dB to V), and I will get 23,98 dB, not 2.5. Thus, LTSpice converted 20 to 26.02 dB and then, instead of dividing, it subtracted from 50 dB 26.02 dB and result is 23.98 dB.

So, the main question is how can I do conversion from dB to V in ac analysis by using directive .meas? May be some other options or directives, or smth... Or I can't use other units, except dB, in .meas ac analysis?

With best regards, Artem.


Well-Known Member
Most Helpful Member
In the plot, just change the axis from log to linear. Dunno about .meas
I'm having the same problem. I use the .meas statement to calculate the voltage drop between two nodes (L1 and L2) at a certain frequency.

.meas ac VL12 find V(L1)-V(L2) at=50

The result is given in dB. Unfortunately, I cannot change the axis from log to linear, as I have no axis. I just do the simulation for this single frequency of 50 Hz.

Is it nevertheless possible (and how) to output the wanted voltage in V, not just in dB?
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