[time-nuts] low phase noise, noise floor and noise figure amplifier at 400MHz

[Lifespeed]

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at lists.febo.com] On Behalf Of
jimlux
Sent: Thursday, January 9, 2020 6:02 PM
To: time-nuts at lists.febo.com
Subject: Re: [time-nuts] low phase noise, noise floor and noise figure
amplifier at 400MHz

So you've tried something like the minicircuits CMA-5043? 18dB gain,
0.75 dB NF, P1dB 18dBm

They've got a whole raft of 0.5dB NF with 20+ dB gain, P1dB in the 17-19 dBm
range - SAV-331, SAV-541, etc.

 From the graphs, the NF is down around 0.3 dB below 500 MHz, if you keep it
reasonably cool (25C.. +85 the NF goes up)

If you need lower than that, I can ask around about discrete designs. 
There's some group in Norway that is using FETs from Switzerland and 
getting L band noise temps in the single digit Kelvin range. (without 
cryocooling).  I don't know if it would go down to UHF and hold that 
performance

***********

While there are lots of low NF options, this does not necessarily correlate
with low PN.  Residual phase noise typically is not characterized and is
left as an exercise for the user.  My experience has been PHEMTs (CMA-5043)
are not one of the better GaAs parts for low phase noise.  The part with 2dB
PN degradation is a Mini-Circuits GALI-6+ InGaP HBT, and it is better than
any off-the-shelf 50 ohm amplifier I have tried so far.

I think it is likely I will need a Si or SiGe bipolar discrete design.  I
have been reading an old paper " Guidelines for Designing BJT Amplifiers
with Low 1/f AM and PM Noise" linked on the NIST site and elsewhere.
https://tf.nist.gov/general/pdf/1139.pdf

Thanks,

Lifespeed