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    25.
    发明专利
    未知

    公开(公告)号：DE69025726D1

    公开(公告)日：1996-04-11

    申请号：DE69025726

    申请日：1990-12-03

    Applicant: IBM

    Inventor： JOVE STEPHEN ALAN ,  KLAASSEN KLAAS BEREND ,  TRAN LONG

    IPC: G11B5/39 ,  G01R33/09 ,  G11B5/02 ,  G11B5/035 ,  G11B5/09

    Abstract: A circuit for producing a signal whose magnitude is a chosen amplitude compensation characteristic of the signals produced by a magnetoresistive (MR) element 10 comprising an input stage G1,G2 which produces an amplified output signal which is coupled to the output stage, and control signals I1,I2 proportional to the resistance of the MR element and inversely proportional to the resistance of the MR element which are coupled to a feedforward circuit 20. The feedforward circuit generates a chosen amplitude equalization characteristic of the signals coupled to the feedforward circuit, and this signal is coupled to a bias terminal of the output stage so that the output stage produces a signal representing the chosen amplitude compensation characteristic of the signals produced by the MR element.

    Protective circuit for magnetoresistive element
    27.
    发明专利
    Protective circuit for magnetoresistive element 未知

    公开(公告)号：HK139294A

    公开(公告)日：1994-12-16

    申请号：HK139294

    申请日：1994-12-08

    Applicant: IBM

    Inventor： JOVE STEPHEN ALAN ,  KLAASSEN KLAAS BEREND ,  NOMURA CALVIN SHIZUO ,  VAN PEPPEN JACOBUS LEONARDUS

    IPC: G11B5/39 ,  G11B5/00 ,  G11B5/02 ,  G11B5/40 ,  G11B19/04 ,  H03F3/72

    Abstract: The invention relates to a protection circuit for a magnetoresistive (MR) element (Rh) having a first terminal and a second terminal in which a first current source is coupled to the first terminal of the MR element to produce a bias current (J1) through the MR element and a second current source is coupled to the second terminal of the MR element to produce a reference current (Iref). According to the invention, circuit means (R,R,B) coupled across the MR element (Rh) senses the centre potential of the MR element substantially midway between the first and second terminals, and a feedback circuit (B) responsive to the sensed centre potential adjusts the current output of the first current source (J1) to maintain the centre potential to a selected reference voltage (Vcentre) to protect the MR element (Rh) from short circuits to a conductive area of the magnetisable recording medium being read by the MR element.

    28.
    发明专利
    未知

    公开(公告)号：DE69103321D1

    公开(公告)日：1994-09-15

    申请号：DE69103321

    申请日：1991-05-01

    Applicant: IBM

    Inventor： JOVE STEPHEN ALAN ,  KLAASSEN KLAAS BEREND ,  NOMURA CALVIN SHIZUO ,  VAN PEPPEN JACOBUS CORNELIUS L

    IPC: G11B5/02 ,  G01R33/09 ,  G11B5/00 ,  G11B5/39 ,  G11B5/40 ,  G01R33/06

    Abstract: An amplifier circuit produces an electrical output signal whose magnitude is representative of a signal produced by a magnetoresistive (MR) element (Rmr) and also protects the MR element (Rmr) from electrical short circuits between the element (Rmr) and on adjacent conductive surface. A first feedback loop biases the MR element (Rmr) with a bias current and amplifies a signal current for causing the MR element (Rmr) to produce a circuit output signal corresponding to dRh/Rh and in which any dc offset error is minimized R h is the resistance of the MR element and dRh is the magnetic-signal-induced change in the resistance of the MR element. A second feedback loop insures that the MR element (Rmr) is held at a preselected reference potential and that no current will flow sufficiently to damage the element in the event of a short circuit between the element and the surface. The feedback loops are interconnected by outputs of the respective feedback loops being commonly connected to the bases of a pair of input bipolar transistors (Q1,Q2), whose respective emitters are connected to opposite terminals of the MR element (Rmr).

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