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Article: In-between spaces.(measuring inductance)(Column)
- Article from:
- EDN
- Article date:
- May 24, 2007
- Author:
CopyrightCOPYRIGHT 2007 Reed Business Information, Inc. (US). This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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by Howard Johnson, PhD
I measured the inductance of four loops of wire. Each loop comprises the same length of insulated #10 AWG solid-copper wire (Figure 1 ). During testing, I probe the wires at their endpoints (bottom of figure ), holding the wires vertically above the tester and well away from all other metal objects.
The leftmost loop, the round one, has a diameter of 10 in. It gives the largest inductance at 730 nH. Moving to the right, the inductance drops in each case until you reach the final loop, the twisted wire, at 190 nH.
I mention this simple experiment because I have all too often heard engineers say: 'My via has an inductance ...