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Design >> RF Design >> Magnetic field in the center of an on-chip transformer
https://designers-guide.org/forum/YaBB.pl?num=1410918792

Message started by Nath on Sep 16^th, 2014, 6:53pm

Title: Magnetic field in the center of an on-chip transformer
Post by Nath on Sep 16^th, 2014, 6:53pm

Hi,
I have a fundamental question about the magnetic field in the center of an inter-wound symmetric monolithic transformer. As I understand it, the built in phase inversion from the primary to secondary of an inter-wound (lateral) transformer results in ZERO magnetic field at the center.
This is quite contrary to a spiral inductor whose field is strongest in the center. Does this make sense or am I not looking at this correctly?

Regards,
Nath

Title: Re: Magnetic field in the center of an on-chip transformer
Post by loose-electron on Sep 17^th, 2014, 8:09am

care to provide a picture of what you are talking about?

Title: Re: Magnetic field in the center of an on-chip transformer
Post by aaron_do on Sep 18^th, 2014, 4:28am

Hi Nath,

I believe your reasoning is correct. The currents in the primary and secondary will be going in the opposite direction and the magnetic fields which they produce will cancel at the center of the transformer.

Aaron

Title: Re: Magnetic field in the center of an on-chip transformer
Post by totowo on Nov 13^th, 2014, 11:25pm

According to Lenz's law, the secondary current is really trying to cancel the magnetic flux, but it is always more 'weak' to cancel all. :)

Nath wrote on Sep 16^th, 2014, 6:53pm: