[time-nuts] Effect of EFC noise on phase noise

Alex Pummer alex at pcscons.com
Mon Aug 1 23:31:41 EDT 2016

Ja Gerhard, bitte schicke mir den LTSpice file,

Danke im Voraus und

On 8/1/2016 6:34 PM, Gerhard Hoffmann wrote:
> Am 02.08.2016 um 02:42 schrieb Bruce Griffiths:
>> /"I'm working on a new amplifier based on IF3602 or BF862 FETs that can
>> use 10u foil only."/
>> /
>> /
>> Similar to that published by Groner in Linear Audio?
>> /
>> /
> I know that Groner exists from some web site, but had no personal 
> contact.
> Also I don't read Linear Audio other than 2 articles from Scott Wurcer 
> that I've bought.
> I highly regard Scott, he's the father of the AD797 after all and AD 
> fellow.
> I also had some conversations with him on that.
> The preamp will be classical.  Some JFETs in parallel, no source 
> resistors except
> half an Ohm for feedback, more would add to the input noise voltage.
> Cascode with a Zetex bipolar (or whatever they are called now).
> OP37 for loop gain. feedback from OP37 output for 50 or 60 dB gain.
> Post amplifier to 80 db or so.
> Without the cascode, the 1 MHz is not possible. It does not help that
> the feedback limits the voltage excursions on the drain.
> I'm not yet sure about the effective input capacitance. I get abt. 1 
> or 1.5 MHz
> bandwidth from a low impedance source. A few nF on the input capacitance
> would be ok, in the end I want it after a ring mixer for phase noise 
> measurements
> but I get unreasonably more in simulation, depending on if I measure 
> it from
> upper frequency corner with a larger input resistor or the resonance 
> frequency
> with an added inductor.
> You can get the LTspice file if you like.
> regards, Gerhard
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