Amplifier circuit suppressing disturbance signal produced by magnetoresistive head
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsTakehiko Umeyama, Tsutomu Kamifuji
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Abstract
An amplifier for an MR head comprises a means for switching cut-off frequencies of a plurality of lowpass filters, when a data signal superposed by a disturbance signal (a composite signal) is input from an MR head, a means for extracting the disturbance signal from the composite signal, a means for adding the extracted disturbance signal to the composite signal. Accordingly, it possible to obtain a data signal less influenced and less distorted even if a disturbance signal appears.
Claims12
An amplifier for a magnetoresistive (MR) head comprising:
- a non-inverting input terminal for receiving from an MR head a composite signal including a data signal on which a disturbance signal is superposed;
- an inverting input terminal for receiving an inverted signal, an inversion of the composite signal input to the non-inverting input terminal;
- a first differential amplifier for receiving the signal input to the non-inverting input terminal at a first, non-inverting input terminal, for receiving the signal input to the inverting input terminal at a second, inverting input terminal, and outputting the two signals differentially amplified;
- an LPF switching signal generation circuit receiving the signal input to the non-inverting input terminal for generating a control signal having a fixed period when a disturbance signal is superposed on a data signal;
- a first low pass filter receiving the composite signal from the non-inverting input terminal and the control signal, switching cut-off frequencies according to the control signal, and outputting a filtered signal to an inverting output terminal of the amplifier for an MR head;
- and
- a second low pass filter receiving the composite signal from the inverting input terminal and the control signal and switching cut-off frequencies according to the control signal and outputting a filtered signal to a non-inverting output terminal of the amplifier for an MR head.
An amplifier for a magnetoresistive (MR) head comprising:
- a first input terminal receiving from an MR head a composite signal including a data signal on which a disturbance signal is superposed;
- a second input terminal receiving a signal that is an inversion of the composite signal input to the first input terminal;
- a first differential amplifier receiving the signal input to the first input terminal at a non-inverting-input terminal, for receiving the signal input to the second input terminal at an inverting input terminal, and outputting the two signals differentially amplified;
- an LPF switching signal generation circuit receiving the signal input to the first input terminal for generating a first control signal having a first fixed period and a second control signal having a second fixed period when the disturbance signal appears from an MR head;
- a first low pass filter receiving the composite signal from the first input terminal and the first and second control signals for switching cut-off frequencies according to the first and second control signals, and for outputting a filtered signal to an inverting output terminal of the amplifier for an MR head;
- and
- a second low pass filter receiving the signal from the second input terminal and the first and second control signals for switching cut-off frequencies according to the first and second control signals, and for outputting a filtered signal to a non-inverting output terminal of the amplifier for an MR head.
Dependencies are inferred from the claim text.