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公开(公告)号：CA1268223A
公开(公告)日：1990-04-24
申请号：CA532246
申请日：1987-03-17
Applicant: IBM
Inventor： JOVE STEPHEN A , KLAASSEN KLAAS B
Abstract: AMPLIFICATION OF SIGNALS PRODUCED BY A CURRENT BIASED MAGNETORESISTIVE SENSOR A transimpedance amplifier for biasing and amplifying the signals produced by a magnetoresistive element is provided. Electrically, the resistance of the element is disposed as degenerative feedback in the emitter circuit of a differential pair comprising the input stage of the amplifier. Bias current for the element is supplied by the same current source that supplies current to the differential pair. DC feedback to the input stage balances current flow in both paths of the differential input stage to correct for DC offset arising in the output from variations transistor characteristics and the steady-state value of the magnetoresistive element. The amplified signal, representing .DELTA.Rh/Rh, is sensed as a current through the magnetoresistive element, where .DELTA.Rh is the change in steady-state resistance, Rh, of the element.
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公开(公告)号：CA1330832C
公开(公告)日：1994-07-19
申请号：CA600082
申请日：1989-05-18
Applicant: IBM
Inventor： JOVE STEPHEN A , KLAASSEN KLAAS B , VAN PEPPEN JACOBUS C L
IPC: G11B5/09 , G11B5/00 , G11B5/012 , G11B5/02 , G11B5/40 , G11B19/04 , G11B20/00 , G11B20/22 , G11B33/10
Abstract: A method and circuitry are disclosed for suppressing additive transient disturbances in a data channel; e.g., due to thermal transients caused by a magneto-resistive (MR) transducer contacting moving a storage surface. Positive and negative envelope detectors each have their inputs connected to the channel, and provide respective outputs which are summed and contain an envelope component and a residue component. A buffer interconnects the detectors to allow both detectors to follow rapid positive excursions of the data channel signal. A nonlinear signal-adaptive filter is connected to the summed output to further reduce the residue component. The data channel signal (or preferably the output from a delay means connected to the channel) is summed with the output from the filter. The relative amplitudes of these two outputs is set such that the resulting summed output signal is free of additive disturbances.
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公开(公告)号：CA1326072C
公开(公告)日：1994-01-11
申请号：CA534767
申请日：1987-04-15
Applicant: IBM
Inventor： JOVE STEPHEN A , KLAASSEN KLAAS B , NOMURA CALVIN S , VAN PEPPEN JACOBUS C L
Abstract: VOLTAGE AMPLIFIER FOR CONSTANT VOLTAGE BIASING AND AMPLIFYING SIGNALS FROM A MR SENSOR An amplifier for voltage biasing and amplifying the signals produced by a magnetic sensor is provided. Electrically, the resistance of the sensor is disposed between the bases of a differential pair comprising the input stage of the amplifier. Constant bias voltage for the sensor is provided independently of sensor resistance. DC feedback to the input stage balances current flow in both paths of the differential input stage to correct for DC offset arising in the output from input stage emitter resistor. The amplified signal, representing ?Rh/Rh, is sensed as a voltage across the magnetoresistive sensor, where .DELTA.RH the change in steady-state resistance, Rh, of the sensor.
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公开(公告)号：CA1180442A
公开(公告)日：1985-01-02
申请号：CA414991
申请日：1982-11-05
Applicant: IBM
Inventor： JOVE STEPHEN A , VAUGHN JULIAN E
Abstract: PSK MODULATION IN AC BIAS DATA RECORDING In a data recording system employing an AC bias signal that is superimposed on the data signal, the AC bias signal is phase modulated to compensate for the difference in the phase angle between the alternating bias and the data signals. The frequency of the AC bias signal is no greater than ten times the frequency of the data signal.
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