Dynamic magnetic information storage or retrieval – General recording or reproducing – Specifics of the amplifier
Reexamination Certificate
1998-08-10
2001-04-24
Faber, Alan T. (Department: 2651)
Dynamic magnetic information storage or retrieval
General recording or reproducing
Specifics of the amplifier
C360S046000, C327S110000, C365S242000
Reexamination Certificate
active
06222695
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to integrated circuits. In particular, the present invention relates to a system and method for reducing signal rise/fall time for an integrated circuit used in a disk drive assembly.
BACKGROUND OF THE INVENTION
A preamplifier is an integrated circuit used in a disk drive assembly to condition and process data which are retrieved from and stored on a magnetic storage medium, such as a magnetic disk. “Read” circuits in the preamplifier amplify magnetic signals sensed (retrieved) by a read head flying over the magnetic disk. “Write” circuits in the preamplifier apply signals (current pulses) to a write head to be stored as magnetic signals on the disk.
An example of current pulses applied to a write head by a write circuit is shown in FIG.
1
. The current creates a magnetic field which is typically stored on a disk. As the frequency of the current pulses is increased, so is the density of the stored data. Since it is desirable to increase the density of stored data, it is likewise desirable to increase the frequency of the current pulses. The time required for the current to change from its present value to its next value (rise and fall times
10
A-
10
B) ultimately limits the frequency of the pulses, therefore it is desirable to reduce the rise and fall times
10
A-
10
B. Accordingly, if the rise/fall speed of the current applied to the write head increases, the writing speed increases.
It would be desirable to improve the rise/fall speed of the current being applied to the write head in order to increase the speed at which the write head can write data into the magnetic mass storage memory. The present invention addresses such a need.
SUMMARY OF THE INVENTION
Embodiments of the present invention present preamplifier write circuits for increasing the speed at which a write head in a disk drive assembly writes to a memory, such as a magnetic disk memory. The embodiments of the present invention increase the speed at which currents through the write head rise and fall. According to embodiments of the present invention, a current source in the write circuit is bypassed during rise and fall times. Bypassing the current source increases the voltage across the write head, increasing in the rise/fall speed of the current pulses applied to the write head. The embodiments of the present invention allow data to be written faster than conventional write circuits. Accordingly, the density of the data stored on disk is increased.
A write circuit according to an embodiment of the present invention for facilitating a write head for writing to a memory, such as a magnetic disk, in a computer system is presented. The write circuit comprises a supply voltage source configured to provide current to the write circuit. The write circuit also includes a current source coupled to the supply voltage source, the current source being configured to maintain the current at a predetermined value. Additionally, the write circuit also includes a switch coupled to a current source, the switch being configured to bypass the current source during a time when the current is changing.
In another aspect of the present invention, a method according to an embodiment of the present invention for facilitating a write head for writing to a memory in a computer system is also presented. The method comprising steps of providing a current to a write circuit; changing the current; and bypassing a current source during a time when the current is changing.
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European Search Report dated Feb. 12, 1999 for application No. EP 99113536.9.
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Faber Alan T.
Fish & Richardson P.C.
Siemens Microelectronics, Inc.
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