[time-nuts] 74AC gates phase noise

[Richard (Rick) Karlquist]

Bruce Griffiths wrote:

> Only if the noise figure of the following amplifier is 4dB or so.
> With no extra amplification is used one only needs a signal level of 
> +1dBm to achieve a phase noise floor of -178dBc/Hz if the output is 
> extracted through the crystal in such a way that the thermal noise of 
> the load dominates.

Read US Patent 4283691, which explains how the 10811 works.  The
situation is far more complicated than the simple analysis above.
If you play your cards right, you can get much better phase noise
than what you have indicated.  The thermal noise of the load does
not enter into it.  Unfortunately, the very low noise first stage
in the 10811 is degraded by the emitter follower after it.  As I
previously stated, you can bypass these additional stages if you
want a lower phase noise floor.

Rick Karlquist N6RK