J
Joel Kolstad
Does anyone around here bother to have the ground plane underneath, say, an
0402 capacitor removed? I ran through some numbers, and it looks like you can
easily end up with something in the ballpark of many tens to the low hundreds
of femtofarads by not doing so -- if your "circuit" capacitors are only in the
couple pF range anyway, this seems like it could be significant. I'm
operating the hundreds of MHz ballpark, so I'm not too worried about
"non-lumpedness" yet by doing this.
I've seen data sheets such as that of the Analog Devices AD8045 1GHz GBW
op-amp suggest removing the ground planes from underneath the input and output
pins to avoid creating a pole that might noticeably reduce the device's GBW...
Thanks,
---Joel Kolstad
0402 capacitor removed? I ran through some numbers, and it looks like you can
easily end up with something in the ballpark of many tens to the low hundreds
of femtofarads by not doing so -- if your "circuit" capacitors are only in the
couple pF range anyway, this seems like it could be significant. I'm
operating the hundreds of MHz ballpark, so I'm not too worried about
"non-lumpedness" yet by doing this.
I've seen data sheets such as that of the Analog Devices AD8045 1GHz GBW
op-amp suggest removing the ground planes from underneath the input and output
pins to avoid creating a pole that might noticeably reduce the device's GBW...
Thanks,
---Joel Kolstad