[time-nuts] Phase measurement of my GPSDO

[Gerhard Hoffmann]

Am 03.04.20 um 23:08 schrieb Bruce Griffiths:
> One can merely add diodes to the opamp feedback network form a feedback limiter and maintain the opamp outputs within the range for which the opamp is well behaved whilst maintaining the increase in slew rate for the output.

Has anybody here  ever tried the OPA698 / OPA699 limiting op amps?

http://www.ti.com/lit/ds/symlink/opa698.pdf

A lower 1/f corner would be appreciated, and slightly less noise.

>> On 04 April 2020 at 04:26 Tobias Pluess <tpluess at ieee.org> wrote:
>>
>>
>> Jup, some of them even have phase reversal when they are overloaded, so it
>> is perhaps not a good idea in general, but I think there are opamps which
>> are specified for this.

That phase reversal thing is a misfeature of old JFET-OpAmps when

overdriven at the input. It created weird behavior of feedback loops.

Newer ones have that corrected.


Cheers, Gerhard