[sdiy] what does low-k mean?? and how do i tell a high-k ceramic cap?

[harry bissell]

Small cap values in any size pagkage are usually "low-k" as in
C0G or NP0 dielectrics

Larger cap values in small packages are getting toward "high-k"

X7R is not too bad but its not good for critical or stable timing

Z5U is getting pretty bad... its "high-k" and good for decoupling

worse than that... I'd wonder if they are good for anything  :^P

Ian's advice was good... shop temperature stability and tolerance.



Brett Maddaford wrote:
> Big thanks to all that replied to my question on this....i now
> understand the difference between low and high k and why to avoid the
> high k's.
>
> I am still not sure how to tell whats what when ordering, many sites
> don't specify if the caps are low or high k and some suppliers have
> looked at me really confused when I have asked???? How do I tell the two
> apart?
>
> Thanks again for all the great info
>
> Brett
>
> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl
> [mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of anthony
> Sent: Wednesday, 30 August 2006 1:12 AM
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] what does low-k mean?? and how do i tell a high-k
> ceramic cap?
>
> Yes! That is what I was thinking of. But you explained it much better
> than I would have anyway.
>
>   
>> At 12:44 AM 8/29/2006, anthony wrote:
>>     
>>> The actual word is on the tip of my brain,
>>>       
>> Permittivity?  It relates induced polarization -- the charge stored in
>>     
>
>   
>> a cap -- to the applied electric field.  There are different kinds of 
>> hi-k caps.  Hi-k ceramics operate close to the ferroelectric phase 
>> transition, which gives them a large temperature coefficient and make 
>> control of the cap value difficult.
>>
>>
>>     
>
>
>
>
>
>