Apparatus for measuring magnetic field of microwave-assisted head
US8358127B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 7, 2010 |
| Grant date | Jan 22, 2013 |
| Priority date | — |
| Expiry date | Apr 19, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/1284
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A measuring circuit system in a magnetic field measuring apparatus of the invention has an amplifier and a band-pass filter connected in sequence on an output terminal side of the TMR element, the band-pass filter is a narrow-range band-pass filter such that a peak pass frequency of the filter that is a center is a basic frequency selected from a range of 10 to 40 GHz and a band width centered around the basic frequency is a narrow range of ±0.5 to ±4 GHz; and with the measuring circuit system, an SIN ratio (SNR) of 3 dB or greater is obtained, the SNR being defined by a ratio of an amplitude S of a high-frequency generated signal induced by the TMR element to a total noise N that is a sum of a head noise generated by the TMR element and a circuit noise generated by the amplifier. With such a configuration, an in-plane high-frequency magnetic field generated by a microwave-assisted magnetic head is reliably and precisely measured.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.