Method and apparatus for increasing the speed of write driver circuitry
AssigneeInternational Business Machines Corporation
InventorCharles J. Masenas
Life of this patent
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Abstract
An H-driver circuit is provided that has a mechanism for selectively reducing one or more RC time constants within the H-driver circuit. Selectively reducing one or more RC time constants within the H-driver circuit reduces the turn-ON time of one or more of the H-driver circuit's pull-up transistors, and increases the speed of the H-driver circuit with little increase in power consumption. Each RC time constant preferably is selectively reduced via a feedback path between an output terminal of the H-driver circuit and a resistance reducer operatively coupled to the pull-up transistor whose turn-ON time is to be reduced. Preferably the resistance reducer comprises a transistor, more preferably a MOSFET and most preferably a p-channel MOSFET.
Claims23
Cross-coupled H-driver apparatus comprising:
- a pair of transistor circuits each coupled to complementary inputs for simultaneously receiving complementary input signals;
- and
- each of the transistor circuits including feedback devices directly coupled to a voltage terminal and cross-coupled for providing positive feedback to the other of the pair of transistor circuits.
An H-driver circuit comprising:
- a first pull-up transistor having a first lead and a second lead;
- a first current path operatively coupled to the first lead of the first pull-up transistor and having a first RC time constant associated therewith;
- and
- a first mechanism operatively coupled to the first lead of the first pull-up transistor for selectively reducing the first RC time constant of the first current path.
An H-driver circuit for driving a write head of a magnetic storage system comprising:
- a first and a second voltage supply rail;
- a first and a second pull-up means operatively coupled to the first voltage supply rail;
- a first pull-up resistor operatively coupled between the first voltage supply rail and the first pull-up means such that the first pull-up means is characterized by a first pull-up resistance;
- a second pull-up resistor operatively coupled between the first voltage supply rail and the second pull-up means such that the second pull-up means is characterized by a second pull-up resistance;
- a first pull-down means operatively coupled to the first pull-up means and to the second voltage supply rail;
- a second pull-down means operatively coupled to the second pull-up means and to the second voltage supply rail;
- a first output terminal operatively coupled to the first pull-up means and to the first pull-down means;
- a second output terminal operatively coupled to the second pull-up means and to the second pull-down means;
- a first feedback means operatively coupled between the second output terminal and the first pull-up means for selectively reducing the first pull-up resistance of the first pull-up means;
- and
- a second feedback means operatively coupled between the first output terminal and the second pull-up means for selectively reducing the second pull-up resistance of the second pull-up means.
A method for selectively reducing one or more RC time constants of an H-driver circuit having a first pull-up transistor characterized by a first pull-up resistance, a first output terminal operatively coupled to the first pull-up transistor, a second pull-up transistor characterized by a second pull-up resistance, and a second output terminal operatively coupled to the second pull-up transistor, the method comprising:
- providing a first mechanism operatively coupled to the first pull-up transistor for selectively reducing a first RC time constant of the H-driver circuit;
- and
- selectively reducing the first RC time constant of the H-driver circuit via the first mechanism.
Dependencies are inferred from the claim text.