Why drill vias on PCB can reduce inductance ?

[opa627bm]

Holes everywhere

[helloworld922]

Inductors in parallel reduce the equivalent inductance, similar to parallel resistors reducing the equivalent inductance.

Larger vias also have less inductance. So why use more vias over larger vias?

1. A lot of small vias may be easier to place on a board than a large via, especially if you have oddly shaped areas available.
2. Even though a larger via will have less inductance, the inductance reduction is roughly proportional to circumference. This increases linearly with radius, while area increases with the square of radius. So you're better off using a bunch of small vias over an equivalent area large via to reduce the net inductance as much as possible.

[Harvs]

Because it provides multiple conduction paths. In order to reduce inductance you need to minimise the loop area between the trace and ground. If the chip's ground path is through a via on the opposite side of the board it will have a large loop area despite having the ground plane directly underneath. So, lots of vias to stitch the ground copper together can reduce the impedance.

[opa627bm]

Thanks everyone! I am trying to design a mini USB DAC and I rarely touch digital stuff. I am an Analog guy 

[c4757p]

Isn't this kind of the analog side of digital anyway?

[Resistoid]

Hello opa627bm.

I agree with the answers given by helloworld922 and Harvs.

See the explanation given by analog guru, the late Jim Williams, in Linear Technology Application Note "AN47 High Speed Amplifier Techniques", pp.24-25:

http://www.linear.com/search/search.php?q=an47

(You may need to copy the above link, paste it into your location bar and then click on the pdf: I've not been able to get a direct link to the paper itself).

Resistoid.

[jahonen]

I have always wondered why there is usually no convenient "stitching via spraycan" tool in PCB design software for placing those ground stitching vias while obeying design rules, just boring regular patterns

Regards,
Janne

[qno]

There is a via stitching in the latest Altium version.
I did not use it.

[jmc2000]

via stitching also raises and broadens the resonant frequency of the power planes.

[ivan747]

I have always wondered why there is usually no convenient "stitching via spraycan" tool in PCB design software for placing those ground stitching vias while obeying design rules, just boring regular patterns

Regards,
Janne

This can be kind of done in Diptrace, you can place a grid of PTHs but it won't obey design rules. You can also make lines.

[Kremmen]

Really? How is that done, because i would like to use such a feature, but haven't been able to find how to do it in DT.