US 6,307,695 B1Granted

Magnetic disk write channel with damping network

AssigneePhilips Electronics North America Corporation

InventorSanjay Manohar Bhandari

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Abstract

A device for writing information to a magnetic medium includes an inductive head and a write amplifier coupled to the inductive head. The write amplifier receives an information signal, and amplifies the signal to provide a current through the inductive head to generate a flux at the inductive head which flux writes a bit of the information on the magnetic medium. The current for each bit of information is characterized by a rising portion, a peak portion, and a settling portion. A damping network is coupled to the inductive head, and couples a low impedance path to the head and the write amplifier, after the current reaches the peak portion, to divert current from the head to reduce a duration of the settling portion of the current. The write amplifier and damping network are embodied together in an integrated circuit, and are programmable via a serial interface.

Claims8

Dependent claims

A device for writing information to a magnetic medium, said device comprising:

an inductive head having a first terminal and a second terminal;
a write amplifier coupled to the inductive head, said write amplifier receiving an information signal corresponding to said information, amplifying said information signal, and driving a current, corresponding to the amplified information signal, through the inductive head to generate a magnetic flux at the inductive head, said magnetic flux writing a bit of the information on the magnetic medium, the current corresponding to each bit of the information having a rising portion, a peak portion, and a settling portion;
a damping network coupled to the inductive head;
and
a further damping network also coupled to the inductive head, wherein the damping network comprises:
a low impedance branch having a first resistive element;
means for detecting the current through the inductive head, said detecting means sensing a voltage across the inductive head, said detecting means comprising a high impedance branch having a second resistive element and a capacitive element coupled to said first terminal of said inductive head;
and
means for coupling the low impedance branch to the inductive head and the write amplifier after said detecting means detects that the current has reached the peak portion, said coupling means comprising a switch connected in series with said first resistive element for coupling the low impedance branch to the second terminal of the inductive head, said switch having a control electrode coupled to a node between the second resistive element and the capacitive element of the high impedance branch such that said switch is rendered conductive in response to the voltage across said inductive head,
whereby said low impedance branch diverts current from the inductive head for reducing a duration of the settling portion of the current,
and wherein the further damping network comprises:
a high impedance branch coupled to said second terminal of said inductive head;
and
a low impedance branch coupled to said first terminal of said inductive head.

11 more elements

An integrated circuit comprising:

connection pins for coupling the integrated circuit to an inductive head external to the integrated circuit;
an amplifier for generating a current for driving the inductive head to write information to a magnetic medium, the current including a rising portion, a peak portion, and a settling portion;
and
a damping network coupled to said connection pins, and a further damping network also coupled to said connection pins, wherein said damping network comprises:
a low impedance path having a first resistive element;
means for detecting the peak portion of the current coupled to one of said connection pins, said detecting means sensing a voltage across said connection pins, said detecting means comprising a high impedance path having a second resistive element and a capacitive element coupled to said one of said connection pins;
and
means for coupling the low impedance path to another of said connection pins in response to said detecting means detecting that the current reaches the peak portion, said coupling means comprising a switch connected in series with said first resistive element for coupling the low impedance branch to said another of said connection pins, said switch having a control electrode coupled to a node between the second resistive element and the capacitive element of the high impedance path such that said switch is rendered conductive in response to the voltage across said connection pins,
whereby the low impedance path diverts current from the connection pin and as a result from the inductive head connected to the connection pins for reducing a duration of the settling portion of the current,
and wherein the further damping network comprises:
a high impedance path coupled to said another of said connection pins;
and
a low impedance path coupled to said one of said connection pins.

10 more elements

Dependencies are inferred from the claim text.