nt: Saturday, January 11, 2020 8:28 AM
> To: Discussion of precise time and frequency measurement
>
> Subject: Re: [time-nuts] Low Phase Noise Amplifiers
>
> FWIW, at the Arecibo Observatory all our cryogenic LNAs had bias stabilized
> with active stabilizers based on opa
-Original Message-
From: time-nuts On Behalf Of Dana Whitlow
Sent: Saturday, January 11, 2020 8:28 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Low Phase Noise Amplifiers
FWIW, at the Arecibo Observatory all our cryogenic LNAs had bias stabilized
-Original Message-
From: time-nuts On Behalf Of Richard (Rick)
Karlquist
Sent: Saturday, January 11, 2020 7:39 AM
To: Discussion of precise time and frequency measurement
; Charles Clark
Subject: Re: [time-nuts] Low Phase Noise Amplifiers
A VERY long time ago, it was discovered
FWIW, at the Arecibo Observatory all our cryogenic LNAs had bias stabilized
with active stabilizers based on opamps. Since the opamps do not work at
~15K,
bias connections to the drain and gate of the RF FETs were brought out
separately
from the RF connections, and the opamp circuitry was at room
A VERY long time ago, it was discovered that simply
degenerating a transistor with an emitter resistor
makes a worthwhile improvement in 1/f noise. I
want to say this was published in 1970 by Dick Baugh
of HP but don't hold me to it. Note that the resistor
was NOT bypassed: it's purpose was RF
Am 11.01.20 um 15:36 schrieb Charles Clark:
I wonder if adding active bias feedback around the RF transistor to
reduce the low frequency current variations would help. This is the
classic PNP bias scheme which can be applied to BJT's or FET's. I
have used it to successfully improve the
I wonder if adding active bias feedback around the RF transistor to
reduce the low frequency current variations would help. This is the
classic PNP bias scheme which can be applied to BJT's or FET's. I have
used it to successfully improve the phase noise on oscillators. Details
from T.T.
