[time-nuts] time-nuts Digest, Vol 91, Issue 168

Bob Camp lists at rtty.us
Wed Feb 29 00:12:50 UTC 2012


Hi

The data sheet is A bit easier to find at http://www.interfet.com/datasheet/IF3601/

Bob



On Feb 28, 2012, at 6:06 PM, Bill Fuqua <wlfuqu00 at uky.edu> wrote:

> At what frequency do you have 1 nv per square root Hz with opamp and
> what opamp ?
>   The 1/f region is the  killer and if it is a low frequency shift in the input
> effectively changing the threshold then you have to be concerned about the
> 1/f region.
>  Discrete embedded JFETs have the best 1/f  of all such as the IF3601.
> Go to www.interfet.com
> 73
> Bill wa4lav
> 
> 
> At 05:11 PM 2/28/2012 -0500, time-nuts-request at febo.com wrote:
>> Date: Tue, 28 Feb 2012 11:51:54 -0800
>> From: gary <lists at lazygranch.com>
>> To: Discussion of precise time and frequency measurement
>>        <time-nuts at febo.com>
>> Subject: Re: [time-nuts] OP-Amps for 10MHz distribution...?
>> Message-ID: <4F4D305A.5030906 at lazygranch.com>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>> 
>> You need to look at the driving impedance before you declare one
>> technology "quieter" than another. That is, you have voltage noise and
>> current noise. For low driving impedance, bipolar will be quieter since
>> current noise will not be significant, plus a bipolar will have lower
>> thermal noise. For high impedance, JFET may be a better solution.
>> 
>> Opamps are around 1nv/rootHz these days. That isn't all that easy to
>> achieve discretely.
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