Quality factor

R

ravi

Guest
What happens to quality factor of capacitor when they are in parallel
or series? For example if one 270pF has minimum Q of 1000 and two
capacitors in parallel with total value of 270pF, (each capacitor has
minimum Q of 1000). What will be total Q in a second case when two
capacitors are paralleled?
 
ravi wrote:
What happens to quality factor of capacitor when they are in parallel
or series? For example if one 270pF has minimum Q of 1000 and two
capacitors in parallel with total value of 270pF, (each capacitor has
minimum Q of 1000). What will be total Q in a second case when two
capacitors are paralleled?
If caps have the same quality, nothing changes,
Click to expand...
either in parr, or in series.
The assembly will have a q of 1000.
 
ravi wrote:
What happens to quality factor of capacitor when they are in parallel
or series? For example if one 270pF has minimum Q of 1000 and two
capacitors in parallel with total value of 270pF, (each capacitor has
minimum Q of 1000). What will be total Q in a second case when two
capacitors are paralleled?
Click to expand...
Where on earth have you found the supposed 'Q' of capacitors stated ?

Graaham
 
On Fri, 10 Sep 2010 03:32:12 +0100, Eeyore
<rabbitsfriendsandrelations@removethishotmail.com> wrote:

ravi wrote:
What happens to quality factor of capacitor when they are in parallel
or series? For example if one 270pF has minimum Q of 1000 and two
capacitors in parallel with total value of 270pF, (each capacitor has
minimum Q of 1000). What will be total Q in a second case when two
capacitors are paralleled?

Where on earth have you found the supposed 'Q' of capacitors stated ?

Graaham
Click to expand...
It's important in RF, especially power RF. It's worth paying a little
more for caps that don't unsolder themselves from the board.

Google high-q capacitor


John
 
John Larkin wrote:
On Fri, 10 Sep 2010 03:32:12 +0100, Eeyore
rabbitsfriendsandrelations@removethishotmail.com> wrote:

ravi wrote:
What happens to quality factor of capacitor when they are in parallel
or series? For example if one 270pF has minimum Q of 1000 and two
capacitors in parallel with total value of 270pF, (each capacitor has
minimum Q of 1000). What will be total Q in a second case when two
capacitors are paralleled?

Where on earth have you found the supposed 'Q' of capacitors stated ?

Graaham

It's important in RF, especially power RF. It's worth paying a little
more for caps that don't unsolder themselves from the board.

Google high-q capacitor
Click to expand...

Donkeys trolls barely understand audio. :(


--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
 
On Sep 10, 12:34 am, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Fri, 10 Sep 2010 03:32:12 +0100, Eeyore

rabbitsfriendsandrelati...@removethishotmail.com> wrote:
ravi wrote:
What happens to quality factor of capacitor when they are in parallel
or series?  For example if one 270pF has minimum Q of 1000 and two
capacitors in parallel with total value of 270pF, (each capacitor has
minimum Q of 1000). What will be total Q in a second case when two
capacitors are paralleled?

Where on earth have you found the supposed 'Q' of capacitors stated ?

Graaham

It's important in RF, especially power RF. It's worth paying a little
more for caps that don't unsolder themselves from the board.

Google   high-q capacitor

John
Click to expand...
It's there specially for NPO caps.
 
On Fri, 10 Sep 2010 03:32:12 +0100, Eeyore
<rabbitsfriendsandrelations@removethishotmail.com> wrote:

ravi wrote:
What happens to quality factor of capacitor when they are in parallel
or series? For example if one 270pF has minimum Q of 1000 and two
capacitors in parallel with total value of 270pF, (each capacitor has
minimum Q of 1000). What will be total Q in a second case when two
capacitors are paralleled?

Where on earth have you found the supposed 'Q' of capacitors stated ?
Click to expand...
---
On the data sheet, if its relevant.

For example, go to:

http://www.panasonic.com/industrial/components/pdf/abj0000ce8.pdf


and peruse the graphs on page EC42.

Note that the sizes given are EIA, (fancy that!) so if you use IEC
sizes the Q might be lower.

---
Another way, if you know that:

X Xc
Q = --- = -----
R ESR

is to get the ESR of the capacitor at the frequency in question,
figure out the capacitive reactance at the frequency in question, and
then do the division.

Yet another way, since the dissipation factor, tan delta, is equal to
the reciprocal of Q, is to get tan delta from the data sheet, (page
EC41 of the provided link), take its reciprocal and, VOILA!, out pops
Q.

Unfortunately, tan delta is only given at one frequency, so the graphs
are probably the best way to go.


For more info:

http://www.atceramics.com/

if you can stand anything with the name: "American" in its title.

---
JF
 
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