Hello, all
I thought it may be of interest to some of the members of this list that TI
is selling evaluation modules for some ultra low noise regulators for $20
in their estore, shipping world wide included. The specs looks pretty
decent to me, and I've ordered up a couple of boards to use as
Ole,
Thanks for bringing it to our attention.
For those that like to click instead of search:
http://www.ti.com/tool/TPS7A4701EVM-094
http://www.ti.com/lit/ug/slvu741a/slvu741a.pdf
http://www.ti.com/product/tps7a4701
http://www.ti.com/lit/ds/symlink/tps7a4701.pdf
/tvb
- Original Message
I have a couple of these. however their noise spectral density tends
to rise precipitously below 1Hz or so. There are regulators with significantly
lower flicker noise.
Bruce
On August 7, 2014 at 6:35 AM Tom Van Baak t...@leapsecond.com wrote:
Ole,
Thanks for bringing it to our
Such as?
david
On 7/08/2014 9:30 PM, bruce-cpdlzquo8hwavxtiumw...@public.gmane.org wrote:
I have a couple of these. however their noise spectral density tends
to rise precipitously below 1Hz or so. There are regulators with
significantly
lower flicker noise.
Bruce
On August 7, 2014
Just practical question..
How would one measure noise at this level? If I were evaluate this what
would I need? My scope lacks a nV/dev setting so is there some way to tell
the difference between this and an LM317? Seriously, what kind of
instrumentation would I need before I could measure an
to measure a power supply noise, better to say the noise spectrum, you
would need a very large non polarized capacitor and spectrum analyzer,
The input of the spectrum analyzer does not like DC, and has low
impedance. Since spectrum analyzer's input impedance is usually 50 ohm,
for to be able
What about a PC sound card?
From: Alexander Pummer alex...@ieee.org
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Thursday, August 7, 2014 5:06 PM
Subject: Re: [time-nuts] Low noise powersupplies
to measure a power supply
b...@evoria.net said:
So, I may throw another cap on it, but it seems to be clean down to what I
can measure at the OCXO on my old Tek 455 with an X10 probe.
Another thing to consider when chasing that sort of problem: How much are you
picking up with your scope probe and/or its ground wire?
the PC sound card has limited bandwidth bellow 20Hz and above 20kHz,
is nothing and also it is not so noise less like a spectrum analyzer
which was made to analyze spectrum and the sound card self is in a
relative noisy environment in the PC
On 8/7/2014 3:09 PM, Bob Stewart wrote:
What
Hi
Your EFC line is probably bypassed internally to the OCXO. A 3db modulation
bandwidth beyond 1 KHz is unlikely. A modulation bandwidth below 100 Hz is
quite possible.
Next thing to consider is that the EFC does FM on the OCXO. Phase noise is PM
modulation. FM is 1/Fmod relative to PM. If
Chris wrote:
Just practical question.. How would one measure noise at this
level? If I were evaluate this what would I need?
Generally, one starts with an extremely low noise amplifier. Note
that isolating the very low frequency AC components from the DC
component is a substantial
Hi
A low noise chopper stabilized op amp can make a pretty good pre-amp to put in
front of a low frequency spectrum analyzer. Something in the 20 to 30 db gain
is adequate for most analyzers. That will get you down to a level that’s well
below the noise floor on any OCXO I have ever seen.
people who designing low noise PLLs solved that problem a while ego go
to Charles Wenzels circuit collections he made a very low noise from DC
to a few hundred kHz amplifier just to amplify the phase noise, here is:
http://www.techlib.com/files/lowamp.pdf
On 8/7/2014 5:05 PM, Bob Camp
he is on the right truck, just look around in your testing environment,
do you have shielded test set up, common ground for all the test gears ?
On 8/7/2014 3:58 PM, Hal Murray wrote:
b...@evoria.net said:
So, I may throw another cap on it, but it seems to be clean down to what I
can
Hi Bob,
I hadn't even considered a filter in the OCXO. This isn't a 10811, but that's
the OCXO I have a schematic of, so I'll assume that's the benchmark. Following
the EFC in, it looks like it goes to a 100K resistor and then tees to the 100pf
varicap and a 15pf to the xtal. Other caps are
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