Abstract: Circuits and methods are provided for write through drivers in disk drive systems. A write through driver is a transceiver that includes a write driver circuit and a receiver circuit. The write driver drives a current signal to a write element through a first conductive interconnect. The write element writes data patterns to a magnetic hard disk in response to the current signal from the write driver circuit. The current signal returns to the receiver circuit through a second conductive interconnect. The return signal can be used for the diagnosis of write-safe conditions.

Abstract: A current-perpendicular-to-the-plane (CPP) magnetoresistive (MR) read head structure has the MR read head located between first and second shields (S1, S2) on a substrate with a shunt resistor R1 connecting S1 to the substrate and a shunt resistor R2 connecting S2 to the substrate, with R1 and R2 being approximately equal. Because R1 and R2 are close enough in value there is no significant interference pickup in the low frequency region. The shunt resistors can be formed from high-resistivity metal nitrides or cermets. The spacing between the substrate and S1 may be selected to make the capacitance between S1 and the substrate approximately equal to the capacitance between S2 and the substrate to substantially reduce interference pickup in the high frequency region.

Abstract: Circuits and methods are provided for write through drivers in disk drive systems. A write through driver is a transceiver that includes a write driver circuit and a receiver circuit. The write driver drives a current signal to a write element through a first conductive interconnect. The write element writes data patterns to a magnetic hard disk in response to the current signal from the write driver circuit. The current signal returns to the receiver circuit through a second conductive interconnect. The return signal can be used for the diagnosis of write-safe conditions.

Abstract: A current-perpendicular-to-the-plane (CPP) magnetoresistive (MR) read head structure has the MR read head located between first and second shields (S1, S2) on a substrate with a shunt resistor R1 connecting S1 to the substrate and a shunt resistor R2 connecting S2 to the substrate, with R1 and R2 being approximately equal. Because R1 and R2 are close enough in value there is no significant interference pickup in the low frequency region. The shunt resistors can be formed from high-resistivity metal nitrides or cermets. The spacing between the substrate and S1 may be selected to make the capacitance between S1 and the substrate approximately equal to the capacitance between S2 and the substrate to substantially reduce interference pickup in the high frequency region.

Abstract: A method and apparatus for reducing crosstalk and signal loss in an electrical interconnect is disclosed. The electrical interconnect includes a laminate. A plurality of signal traces and a subsequent plurality of traces are in a first formed layer of the laminate. The subsequent plurality of traces may be signal traces or power traces. The laminate has a dielectric layer between the first formed layer and a second formed layer. A plurality of serpentine patterns are in the second formed layer of the laminate. The plurality of serpentine patterns is separated from subsequent patterns. The plurality of serpentine patterns supports the plurality of signal traces and the subsequent plurality of patterns supports the subsequent plurality of traces. The supporting of the plurality of signal traces separate from the subsequent plurality of traces reduces write-to-read crosstalk and signal loss.

Abstract: In one illustrative example disclosed, a magnetic storage device includes at least one magnetic disk; a magnetic head which includes first and second read sensors; a suspension which supports the magnetic head relative to the magnetic disk; and read circuitry which includes a preamplifier. The preamplifier has a first input port coupled to the first read sensor; a second input port coupled to the second read sensor; a first bias source coupled to the first input port for actively current/voltage biasing the first read sensor; a second bias source coupled to the second input port for zero biasing the second read sensor; and a subtractor having first and second inputs coupled to the first and the second input ports, respectively. The first input of the subtractor is provided with a first signal which includes a read sensor data signal and an interference signal, whereas the second input of the subtractor is provided with a second signal which includes the interference signal but not the read sensor data signal.

Abstract: An example of a multi-layer structure which may be used for supporting a transducer includes a support layer and an etch stop layer formed from a refractory metal on the support layer. A first electrically conducting layer of copper may be positioned on the etch stop layer. A dielectric layer may be provided on the first electrically conducting layer. A second electrically conducting layer of copper may be provided on the dielectric layer. The dielectric layer is positioned between the first electrically conducting layer and the second electrically conducting layer. The second electrically conducting layer may include a plurality of separate electrically conducting lines.

Abstract: The spacing decrease between pole tips of a write element and a magnetic medium that is associated with the write element is linearly proportional to an input signal, such as an input voltage or current, to a slider flying height controller for a hard disk drive. The flying height controller includes a heater current controller and a multiplexer. The heater current controller receives the input signal and outputs a control current proportional to the input signal. The multiplexer couples the control current to a heating element associated with the write element on a selected slider body during a read operation. The heating element dissipates a power that is proportional to the control current and causes a decrease in the spacing between the pole tips of the write element and the magnetic medium that is linearly proportional to the control current and to the input signal.

Abstract: A magnetic transducer including an electrically conductive shield (ECS) which is disposed between the substrate and first magnetic shield is described. The ECS is preferably embedded in an insulating undercoat layer. The ECS is preferably electrically isolated from the magnetic sensor element and is externally connected to a ground available in the disk drive through the arm electronics. Two alternative ways for connecting the ECS to a ground are described. In one embodiment which is only effective with single-ended input type arm electronics, the ECS is connected to a ground through a via to a lead pad for the read head which is connected to the ground of the arm electronics. In a second and more preferred embodiment a separate lead pad is included on the head to allow the ECS to be connected to electronic or case ground when the head is installed in the arm. The extent of the ECS should be sufficiently large to cover the read head portion of the transducer, i.e.

Abstract: A method (and magnetic recording circuit structure) for write drivers to reduce the reversal time for the current through the inductive recording head, includes a write driver output stage providing a write signal output with a write signal source strength SO, a magnetic write head with a write signal input essentially equal to strength SO, and an interconnect circuit having a characteristic impedance ZO coupled to the write signal output of the write driver output stage and the magnetic write head. The write driver output stage preferably includes a source-side termination circuit having output impedance ZS, wherein the source-side termination circuit output impedance ZS is substantially equal to ZO and the source strength SO of the write driver at the input of the interconnect circuit is temporarily enlarged after every polarity reversal of the write signal for a predetermined time duration &Dgr;t.

Abstract: An example of a method for forming a multi-layer structure which may be used for supporting a transducer includes providing a support layer and forming a etch stop layer from a refractory metal on the support layer. A first electrically conducting layer of copper may be formed on the etch stop layer. A dielectric layer may be provided on the first electrically conducting layer. A second electrically conducting layer of copper may be provided on the dielectric layer. The dielectric layer is positioned between the first electrically conducting layer and the second electrically conducting layer. The second electrically conducting layer may be etched to form a plurality of separate electrically conducting lines.

Abstract: A portable computer includes a battery and a connection to an external power source, a two-speed data storage device being supplied power from one or more of the battery and the external power source, and a controller attached to the storage device. With the invention, when the storage device is powered by the internal battery, the controller not only reduces the rotation speed and the clock rate of the storage device, but also reduces the power consumption of the read/write electronics module inside the disk drive by lowering the power supply voltage for the write driver inside said module and lowering the tail currents for the amplifier stages in the readback amplifier inside said module.

Abstract: An interconnect circuit for a readout channel front-end for a disk drive is disclosed that includes a forward line and a return line. Both the forward line and the return line have a first end and a second end. The first end of both the forward line and the return line is connectable to a magnetoresistive head. The second end of both the forward line and the return line is connectable to a single-ended preamplifier. The return line is arranged to be disposed between the forward line and a suspension for a magnetoresistive head. The forward trace has a first predetermined width and the return trace has a second predetermined width that can be the same or different from the first predetermined width. When the interconnect circuit is in a disk drive, the first end of the forward line is connected to a magnetoresistive head, and the second end of the forward line is connected to a single-ended preamplifier.

Abstract: A method (and magnetic recording circuit structure) for write drivers to reduce the reversal time for the current through the inductive recording head, includes a write driver output stage providing a write signal output with a write signal source strength S0, a magnetic write head with a write signal input essentially equal to strength S0, and an interconnect circuit having a characteristic impedance Z0 coupled to the write signal output of the write driver output stage and the magnetic write head. The write driver output stage preferably includes a source-side termination circuit having output impedance ZS, wherein the source-side termination circuit output impedance ZS is substantially equal to Z0 and the source strength S0 of the write driver at the input of the interconnect circuit is temporarily enlarged after every polarity reversal of the write signal for a predetermined time duration &Dgr;t.

Abstract: A method and system for providing a current-sensing preamplifier for use with a magnetoresistive sensor is disclosed. The method includes providing at least one input device coupled with the magnetoresistive sensor, providing a gain stage, and providing a feedback circuit. In a system aspect, the current-sensing preamplifier includes at least one input device. The at least one input device is coupled with the magnetoresistive sensor through an interconnect having a characteristic impedance. The at least one input device provides an input impedance for the current-sensing preamplifier. The current-sensing preamplifier also includes a gain stage coupled with the at least one input device and a feedback circuit coupled with the gain stage and the at least one input device. The feedback circuit provides at least one signal to the at least one input device. The at least one signal controls the input impedance based on at least one error signal.

Abstract: A magnetic transducer including an electrically conductive shield (ECS) which is disposed between the substrate and first magnetic shield is described. The ECS is preferably embedded in an insulating undercoat layer. The ECS is preferably electrically isolated from the magnetic sensor element and is externally connected to a ground available in the disk drive through the arm electronics. Two alternative ways for connecting the ECS to a ground are described. In one embodiment which is only effective with single-ended input type arm electronics, the ECS is connected to a ground through a via to a lead pad for the read head which is connected to the ground of the arm electronics. In a second and more preferred embodiment a separate lead pad is included on the head to allow the ECS to be connected to electronic or case ground when the head is installed in the arm. The extent of the ECS should be sufficiently large to cover the read head portion of the transducer, i.e.

Abstract: A circuit arrangement for correcting magneto-resistive head asymmetry includes a shift circuit which receives a read signal from a magneto-resistive head, and a polarity signal indicative of the polarity of any asymmetry of the read signal. Depending on the polarity of the asymmetry, the shift circuit either adds or subtracts a shift voltage to the read signal to produce a shifted read signal. The shift circuit outputs the read signal, the shifted read signal, and the shift voltage. First, second and third gain circuits are provided, which receive the read signal, the shifted read signal, and the shift voltage, respectively, and which each receive a respective control signal. The first, second and third gain circuits provide respective outputs amplified proportionally based on the respective control signals. Control circuitry provides the polarity signal to the shift circuit and the respective control signals to the first, second and third gain circuits, based on an amount of correction required.

Abstract: A magnetic-head write-driver circuit includes a write-driver circuit and a by-pass driver circuit coupled in parallel to a signal path between the input and the output of the magnetic-head write-driver circuit. The write-driver circuit receives an input signal having transitions and outputs a first write signal related to the input signal. The by-pass driver circuit outputs an assist signal that is coupled to the first write signal to form an output write signal. The assist signal is related to transitions of the first write signal and assists in shortening reversal time of the transitions of a write signal by producing “overshoots” in the write signal at the time of the transitions. Additionally, the assist signal assists in charging and discharging a parasitic capacitance associated with an output of the magnetic-head write-driver circuit. The assist signal can add a current to, and/or enforce a voltage on, the first write signal to form the output write signal.

Abstract: A magnetoresistive transducer biasing technique that provides a uniform transducer biasing in a product. The technique provides biasing for transducer constant power dissipation, constant sensor current density biasing, constant sensor bias voltage, constant sensor temperature rise biasing, and constant effective magnetic biasing of a transducer.

Abstract: A magnetoresistive transducer biasing technique that provides a uniform transducer biasing in a product. The technique provides biasing for transducer constant power dissipation, constant sensor current density biasing, constant sensor bias voltage, constant sensor temperature rise biasing, and constant effective magnetic biasing of a transducer.