[time-nuts] OP-Amps for 10MHz distribution...?

lists at lazygranch.com lists at lazygranch.com
Wed Feb 29 15:56:50 UTC 2012


System noise is the question. If the driving impedance is low, then voltage noise is more significant than current noise. 

You simply can't look at the noise of the part. The key is the noise of the entire circuit. 

-----Original Message-----
From: Bill Fuqua <wlfuqu00 at uky.edu>
Sender: time-nuts-bounces at febo.com
Date: Wed, 29 Feb 2012 10:15:21 
To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
Reply-To: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Subject: Re: [time-nuts] OP-Amps for 10MHz distribution...?

Low noise voltage at the cost of noise current which is around 1000 times that
of low noise JFETs.

The discussion suggest that opamps contribute to the sideband phase noise
of the signal. I am interested in the mechanism that adds this phase noise.
It would have to be a small shift in either gain (changing Miller 
capacitance) or
an internal capacitance in the opamp.
   I am new to this group and have some catching up to do.

>I know of one op-amp that comes close to 1 nV/rtHz at 10 Hz and being
>capable of useful operation as a 10 MHz distribution amplifier -- the
>ADA4898 (1.2 nV/rtHz at 10 Hz, 4.3 nV/rtHz at 1 Hz).  These are
>wonderful parts, but the large signal frequency response with a 100
>ohm load is less than desired for a 10 MHz distribution amplifier.


73
Bill wa4lav




_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.


More information about the time-nuts mailing list