Power spectral density of flash ADC

hi
in artcle"High-Speed Low-Power Flash ADC Architecture Using
Switched-Capacitor Positive Feedback Comparator and
Parallel Single-Gate Encoder
Saleh Abdel-Hafeez1 · Ali Shatnawi--DOI 10.1007/s00034-017-0673-8"
i have some question that hope anyone answer to me.
1) with notation to image wave_form(attached image) what software the authors have used to draw wave forms? the authors have used hspice to simulation.
2) with notation to power_spectral_density image (attached) how has been calculated snr from power spectral density plot? explenation that in this plot, power spectral density of digital output of a flash adc was plotted.
3) if fft plot of output is the same as power spectral density of output?
thanks

akbarza said:

hi
in artcle"High-Speed Low-Power Flash ADC Architecture Using
Switched-Capacitor Positive Feedback Comparator and
Parallel Single-Gate Encoder
Saleh Abdel-Hafeez1 · Ali Shatnawi--DOI 10.1007/s00034-017-0673-8"
i have some question that hope anyone answer to me.
1) with notation to image wave_form(attached image) what software the authors have used to draw wave forms? the authors have used hspice to simulation.
2) with notation to power_spectral_density image (attached) how has been calculated snr from power spectral density plot? explenation that in this plot, power spectral density of digital output of a flash adc was plotted.
3) if fft plot of output is the same as power spectral density of output?
thanksView attachment 150805View attachment 150804

Click to expand...

I can answer your last question (3): The power spectral density is the modulus of the FFT squared i.e magnitude squared, with no phase information