V
Vitaliy
- Jan 1, 1970
- 0
Hello,
Could someone please explain me the difference between making a pad or
having a straight surface. A picture is worth a thousand words, so I am
attaching a picture with the pad and without the pad.
My application of the pad: ground of analog circuit. So, I am placing
the
capacitor on power rail (between power rail and gnd) to filter the
noise
from power supply and bond wires. My current to power up opamp and for
diode biasing is in milliamps and my voltage is +-5V.
Does it make a difference what I use (as in terms of noise, etc.), if I
have a few of these in the circuit? Should I use instead of pads just
the
straight surface for the ground surface? I know that a pad has some
parasitic capacitance, but then wouldn't the surface have some as well?
I
will be soldering on my own, so I won't be confused at hich components
should go where.
Currently have:
--power---cap-----
--line------pad-----
||||||
||||||
cap
||||||
||||||
cap
|||---gnd---|||
||| pad |||
||| | |||
|||||||||||||||||||||
gnd
surface
Thinking about:
--power---cap-----
--line------pad-----
||||||
||||||
cap
||||||
||||||
|||||||gnd|||||||||
||||||surface|||
|||||||||||||||||||||||
I care because I need to convert very small current (in uA) to volts.
Everything is working fine as it is, but I'm looking to reduce noise as
much as possible to avoid oscillations for higher gain/bw.
Thanks,
Vitaliy
Could someone please explain me the difference between making a pad or
having a straight surface. A picture is worth a thousand words, so I am
attaching a picture with the pad and without the pad.
My application of the pad: ground of analog circuit. So, I am placing
the
capacitor on power rail (between power rail and gnd) to filter the
noise
from power supply and bond wires. My current to power up opamp and for
diode biasing is in milliamps and my voltage is +-5V.
Does it make a difference what I use (as in terms of noise, etc.), if I
have a few of these in the circuit? Should I use instead of pads just
the
straight surface for the ground surface? I know that a pad has some
parasitic capacitance, but then wouldn't the surface have some as well?
I
will be soldering on my own, so I won't be confused at hich components
should go where.
Currently have:
--power---cap-----
--line------pad-----
||||||
||||||
cap
||||||
||||||
cap
|||---gnd---|||
||| pad |||
||| | |||
|||||||||||||||||||||
gnd
surface
Thinking about:
--power---cap-----
--line------pad-----
||||||
||||||
cap
||||||
||||||
|||||||gnd|||||||||
||||||surface|||
|||||||||||||||||||||||
I care because I need to convert very small current (in uA) to volts.
Everything is working fine as it is, but I'm looking to reduce noise as
much as possible to avoid oscillations for higher gain/bw.
Thanks,
Vitaliy