Why drill vias on PCB can reduce inductance ? - Page 1
Forum section: electronics / general

author: opa627bm
author_rank: Regular Contributor
timestamp: March 19, 2013, 03:41:57 am
content: Holes everywhere

author: helloworld922
author_rank: Regular Contributor
timestamp: March 19, 2013, 03:57:10 am
content: 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.

author: Harvs
author_rank: Super Contributor
timestamp: March 19, 2013, 03:57:35 am
content: 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.

author: opa627bm
author_rank: Regular Contributor
timestamp: March 19, 2013, 04:05:54 am
content: Thanks everyone! I am trying to design a mini USB DAC and I rarely touch digital stuff. I am an Analog guy

author: c4757p
author_rank: Super Contributor
timestamp: March 19, 2013, 04:07:21 am
content: Isn't this kind of the analog side of digital anyway?

author: Resistoid
author_rank: Contributor
timestamp: March 19, 2013, 08:59:50 pm
content: Hello opa627bm.I agree with the answers given by helloworld922 and Harvs.See the explanation given by analog guru, the late Jim Williams, inLinear 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.

author: jahonen
author_rank: Super Contributor
timestamp: March 20, 2013, 10:11:45 am
content: 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 patternsRegards,Janne

author: qno
author_rank: Frequent Contributor
timestamp: March 20, 2013, 11:39:19 am
content: There is a via stitching in the latest Altium version.I did not use it.

author: jmc2000
author_rank: Contributor
timestamp: March 26, 2013, 10:52:45 pm
content: via stitching also raises and broadens the resonant frequency of the power planes.

author: ivan747
author_rank: Super Contributor
timestamp: March 28, 2013, 10:06:54 pm
content: Quote from: jahonen on March 20, 2013, 10:11:45 amThis 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.

author: Kremmen
author_rank: Super Contributor
timestamp: April 12, 2013, 06:44:10 am
content: 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.