Re: 3 dB bandwidth

<dhruveenews@xxxxxxxxx> wrote in message
news:1119381672.381374.114100@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Why do we measure the bandwidth of any amplifier as 3 dB down from the
> gain value at DC? Why 3dB? Why not 2dB or 1dB?
> I am not able to find a correct answer as to why did we choose this
> standard.

For a single pole low-pass filter, that drop (3.01 dB, actually)
occurs at the frequency where the straight-line projection of the
passband intersects the asymptote of the stopband. For a
series R/shunt C filter, it also where the magnitude of drop
across the R equals the magnitude on the C. So it is readily
calculated by hand, (as things were when that standard arose).

--
--Larry Brasfield
email: donotspam_larry_brasfield@xxxxxxxxxxx
Above views may belong only to me.


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