Bimodal biasing of magneto resistive heads
AssigneeSTMicroelectronics S.r.l.
InventorsGiuseppe Patti, Axel Alegre de La Soujeole
Life of this patent
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Abstract
A system and method for selecting between two biasing modes for biasing magneto resistive heads in a disk drive. A mode selector selects either a voltage biasing circuit or a current biasing circuit to supply the bias voltage or bias current, respectively, to a magneto resistive head. The selection can be based on changes in parameters in the disk drive or magneto resistive heads during disk drive operation.
Claims17
A data store assembly, comprising:
- a read sensing head;
- and
- a preamplifier configured to selectively supply either a bias voltage or a bias current to the read sensing head, wherein the preamplifier further comprises a biasing mode selector configured to select the bias voltage for connection to the read head and to de-select the bias current, or to select the bias current for connection to the read head and to de-select the bias voltage.
A preamplifier, comprising:
- a bias voltage source;
- a bias current source;
- and
- a mode selector configured to select the bias voltage source for connection to a read head and to de-select the bias current source or to select the bias current source for connection to the read head and to de-select the bias voltage source.
A preamplifier, comprising:
- first and second bias sources;
- a magneto resistive head coupled to the first and second bias sources;
- a mode selector, coupled to the first and second bias sources, configured to select the first bias source for connection to the magneto resistive head and to de-select the second bias source or to select the second bias source for connection to the magneto resistive head and to de-select the first bias source;
- and
- a transconductance amplifier, coupled between the first and second bias sources and the magneto resistive head, configured to provide an offset voltage across the magneto resistive head substantially equivalent to a difference between the bias voltage generated by the first bias source and a reference voltage generated by the second bias source, wherein the reference voltage is supplied to the transconductance amplifier by the second bias source.
An apparatus for selectively supplying a bias voltage or a bias current to a read sensing head of a storage device, comprising:
- a preamplifier configured to selectively supply the bias voltage or the bias current to the read sensing head of the storage device, wherein the preamplifier comprises a mode selctor configured to select one of either the bias voltage source and the bias current for connection to the read head.
A data store assembly, comprising:
- a read sensing head;
- and
- a preamplifier configured to selectively supply either a bias voltage or a bias current to the read sensing head, the preamplifier comprising a transconductance amplifier coupled between first and second biased sources and the read sensing head, the transconductance amplifier configured to provide an offset voltage across the read sensing head substantially equivalent to a difference between the bias voltage generated by the first bias source and a reference voltage generated by the second bias source.
A preamplifier for selectively coupling one of either a bias voltage source or a bias current source to a read head, comprising:
- a mode selector configured to select the bias voltage source for connection to the read head and to deselect the bias current source or to select the bias current source for connection to the read head and to deselect the bias voltage source;
- and
- a transconductance amplifier coupled between the read head and a first voltage source and a reference voltage source, the transconductance amplifier configured to provide an offset voltage across the read head substantially equivalent to a difference between a first voltage generated by the first voltage source and a referenced voltage generated by the reference voltage source.
Dependencies are inferred from the claim text.