[time-nuts] Distribution Amplifier Phase Noise

[Martyn Smith]

Bernd,

We in fact often make -140 dBc @ 1 Hz.

However, our plots are of the amplifier only, not of any reference
oscillator used.

The measurement technique we use cancels out the inherent phase noise of
the source used.

The measurement technique takes a 10 MHz oscillator, splits it into two
legs, phase shift one leg 90 degrees (quadature) and then measures the phase
noise of the two legs.

The phase noise of the source is cancelled out in this measurement
technique.

But remember, you do get oscillators that make -130 dBc/Hz at 1 Hz.

Obviously it is essential for any distribution amplifier to be lower than
the reference used.  10 dB is really the minimum margin that is needed.
This can be very hard to achieve at times.

We can achieve a floor noise of -172 dBc/Hz if we work hard at it.

Regards

Martyn