High speed pre-driver with voltage reference for thin film head write driver
AssigneeTexas Instruments Incorporated
InventorsTuan Van Ngo, Raymond Elijah Barnett
Life of this patent
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Abstract
A preamplifier device (26) for a thin film transducer disk drive system having operation speeds up to and greater than 2 Gb/s. The device (26) includes a low power/high speed driver (203) having a cascaded Class AB buffer. In at least one embodiment the device (26) includes separated drive devices in the driver (203) and H-bridge circuit (205) realized in multiple smaller devices biased separately to reduce transistor self-heating effects and a further embodiment includes a reference (201) having a base cancellation scheme and a Class AB current source for improving accuracy and stability is such high speed devices.
Claims19
A driver system for a disk drive, comprising:
- a switching circuit having an upper pair of switching devices and a lower pair of switching devices coupled in an H-bridge arrangement for switching current polarity through an inductive head;
- a write drive circuit couple with said switching circuit and having transistor devices for providing current to said switching circuit;
- and
- a pre-drive circuit coupled with said write drive circuit for providing an amplified signal thereto and having a first voltage follower device coupled in a cascade arrangement to a second voltage follower device.
A driver system for a disk drive, comprising:
- a switching circuit having an upper pair of switching devices and a lower pair of switching devices coupled in an H-bridge arrangement for switching current polarity through an inductive head;
- a write drive circuit coupled with said switching circuit and having transistor devices for providing current to said switching circuit;
- a pre-drive circuit coupled with said write drive circuit for providing an amplified signal thereto and having a pair of voltage follower devices coupled in a cascade arrangement;
- and
- a reference circuit coupled with said pre-drive circuit for providing a differential ECL data signals to said pre-driver circuit
- wherein said reference circuit further comprises a Class AB operable current mirror coupled with said transistor emitter for stabilizing the voltage at increased switching speeds.
A preamplifier for driving an H-bridge switching circuit in a disk drive system, comprising:
- a write drive circuit coupled with said switching circuit and having transistor devices for providing current to said switching circuit;
- and
- a pre-drive circuit coupled with said write drive circuit for providing an amplified signal thereto and having a first voltage follower device coupled in a cascade arrangement to a second voltage follower device.
A preamplifier for driving an H-bridge switching circuit in a disk drive system, comprising:
- a write drive circuit coupled with said switching circuit and having transistor devices for providing current to said switching circuit;
- a pre-drive circuit coupled with said write drive circuit for providing an amplified signal thereto and having a pair of voltage follower devices coupled in a cascade arrangement;
- and
- a reference circuit coupled with said pre-drive circuit for providing a differential ECL data signals to said pre-driver circuit,
- wherein said reference circuit comprises:
- an output transistor having a base, collector and emitter;
- and
- a current device coupled with said base and collector for providing a compensation current to base,
- wherein said reference circuit further comprises a Class AB operable current mirror coupled with said transistor emitter for stabilizing the voltage at increased switching speeds.
A method for providing a current for driving an inductive head of a disk drive system responsive to a control signal, comprising:
- providing a reference signal responsive to said control signal, said reference signal is provided via an output transistor having a base, collector and emitter;
- wherein a compensation circuit is coupled with said base and collector for providing a compensation current to said base and a Class AB operable current mirror is coupled with said emitter for stabilizing the voltage;
- amplifying said reference signal via transistors operably arranged in a Class AB biasing arrangement;
- and
- providing said amplified signal as a current signal to a switching circuit for switching current polarity through said inductive head, wherein said switching circuit has upper pair of switching devices and a lower pair of switching devices coupled in a conventional H-bridge arrangement.
Dependencies are inferred from the claim text.