公开(公告)号：JPH1166510A

公开(公告)日：1999-03-09

申请号：JP16246798

申请日：1998-06-10

Applicant: ST MICROELECTRON INC

Inventor： MARK H RIATTO

IPC: G11B5/09 ,  G01R33/09 ,  G11B5/00 ,  G11B5/012 ,  G11B5/02 ,  G11B33/12

Abstract: PROBLEM TO BE SOLVED: To improve a bias method of pre-amplifier and MR sensor by supplying a current bias to an MR sensor from a pre-amplifier and then amplifying, with a pre-amplifier, change of electric resistance output, responding to such current bias, from the MR sensor by detecting change of magnetic data flux. SOLUTION: In an integrated circuit 15 for pre-amplifying of a preamplifier 10, a current source sensor bias circuit 20 supplies a current bias to an MR sensor R via a current bias loop circuit 25 from the supply voltage. The loop circuit 25 detects and outputs a change of current bias depending on change of electric resistance due to magnetic data flux by the MR sensor. This output is amplified and output by a first and a second amplifying circuits A1, A2 and an amplifying output circuit 35 and an output current of a stabilizing circuit 38 drives the first amplifying circuit A1 to bias the MR sensor R. Thereby, the bias method of the pre-amplifier for hard disk drive and MR sensor can be improved.