[time-nuts] IFCS 2020 tutorial - low noise electronics for time/frequency metrology

[Richard (Rick) Karlquist]

On 7/21/2020 4:27 PM, Magnus Danielson wrote:

> 
> In capacitors, two things make them microphonic, voltage over the
> capacitor and the high-dielectric constant as this makes it more
> sensitive to mechanical stress, and this also tends to make them very
> sentistive to thermal stress. So X7R is terrible for instance.
> 

The LT3042/LT3045 data sheets should be of interest in this regard.
ADI calls out a particular Murata capacitor that supposedly has low
microphonics.  However, I believe its tempco is X7R, so I can't 
reconcile that with what you said.  It does lose less capacitance
at higher voltages than any other capacitor with a value of 10 uF
that I have seen, so from what you are saying, this should give
it lower microphonics.

Unfortunately, this technology appears to have been orphaned by
Murata, receiving the dreaded NRND notation.  It appears that
it will be available in distribution for the immediate future
at least.

Rick N6RK