Hi Group:
Is there direct FFT or DFT and that will lead one to calculate the PSD (pow er spectral density)implementation that could be done with .measure or B-so urce math in LTspice IV? Special Opamps for very low noise figures would ce rtainly have a noise figure and noise spectral density but the data sheet w ill not give you PSD ?
I can only think of signals and systems theory that if the Auto Correlatio n function exist the according to the Fourier Transform Tables it will have the its corresponding Energy Spectral Density which is well known as Wien er-Khinchin Theorem of course.
Perhaps I'll take a look using the idt(x), sdt(x) and idtmod(x) from the B- source functions and options on .measure. Would appreciate some help from t he members out there.
Thanks.