公开(公告)号：US20130301162A1

公开(公告)日：2013-11-14

申请号：US13726767

申请日：2012-12-26

Applicant: TDK Corporation

Inventor： Isamu SATO ,  Hiroshi IKEDA ,  Mikio MATSUZAKI ,  Tetsuya ROPPONGI ,  Noboru YAMANAKA ,  Tsutomu AOYAMA

IPC: G11B5/455

CPC classification number: G11B5/455 ,  G01R33/098 ,  G01R33/1284

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 S/N 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.

Abstract translation: 本发明的磁场测量装置中的测量电路系统具有在TMR元件的输出端侧依次连接的放大器和带通滤波器，带通滤波器是窄范围带通滤波器， 作为中心的滤波器的峰值通过频率是从10〜40GHz的范围选择的基本频率，以基本频率为中心的频带宽度为±0.5〜±4GHz的窄范围; 并且利用测量电路系统，获得3dB或更大的S / N比（SNR），SNR由TMR元件引起的高频产生信号的振幅S与总噪声的比率定义 N是由TMR元件产生的头噪声和由放大器产生的电路噪声之和。 通过这样的结构，可以可靠且精确地测量由微波辅助磁头产生的面内高频磁场。