Abstract: An apparatus for use in applying write signals for driving a write head to effect writing information to a memory device; the write signals including a first write signal and a second write signal; includes: (a) a directing circuit receiving the write signals, directing a current to establish a voltage across the write head in a first excursion toward a first polarity in response to the first write signal and directing the current to establish the voltage across the write head in a second excursion toward a second polarity substantially opposite the first polarity in response to the second write signal; (b) a first boost system coupled with the directing circuit and boosting the write voltage toward the first polarity during the first excursion; and (c) a second boost system coupled with the directing circuit and boosting the write voltage toward the second polarity during the second excursion.

Abstract: A high speed data transmission channel, preferably embodied in a circuit for writing to a read channel for a hard disk drive, is provided. The channel includes a preamplifier writer, a non-uniform transmission line, and a head. The writer is configured to transmit pulses to the head via the transmission line at a transmission speed. Each pulse has a pulse width. Each pulse may experience interference. The writer is also configured to eliminate interference to each pulse by causing the interference to occur in a differential mode, which causes the interference to cancel out. A transmission time for each pulse is inversely proportional to the transmission speed. The non-uniformity of the transmission line may entail an exponential broadening of a trace width of the transmission line such that when the pulse width is greater than or approximately equal to the transmission time, the pulse propagates from the writer to the head substantially undistorted.

Abstract: A write current circuit (40) adapted to drive a thin film write head (L0) of a mass media information storage device. The write current circuit includes a write current reference voltage circuit (42) adapted to selectively establish amplitude of a write current signal. The write current circuit further includes programming circuitry (M5-M10) driven such that several parameters of the write current waveform can be controlled, including the write current amplitude, overshoot amplitude and overshoot duration. The present invention achieves technical advantages by providing the ability to both produce an accurate write current, and also providing the ability to establish the write current waveform shape so that customers can optimize disk drive performance even when using different thin film write heads available from different suppliers.

Abstract: A method for controlling write current to a write head during data write on a hard disk drive is disclosed. A direct access storage device includes a rotating storage medium in which data are magnetically written, a write head for writing data in the rotating storage medium, and a write current control circuit for changing write current-value settings to be supplied to the write head according to a predetermined elapsed time from the beginning of a write operation.

Abstract: In a magnetic disk drive, a writing element and its surrounding area thermally expand due to the heat generated by a write head coil. The transient phenomenon of such thermal expansion may invoke the transient phenomenon of inadequate writing capacity, thereby causing a writing error at an early stage of a write operation. Control is provided which increases/decreases either or both the write current to be applied to a write head and the amount of its overshoot on an individual sector basis during a writing sequence.

Abstract: An amplifying circuit and method are disclosed for amplifying electrical signals, such as electrical signals generated by the read head of a disk drive. The circuit includes a pair of cross-coupled differential amplifier circuits. Each differential amplifier circuit is asymmetric, including two input transistors of different transistor types. For instance, a first of the two input transistors of each differential amplifier circuit may be a bipolar transistor and a second of the two input transistors may be a field effect transistor. By utilizing asymmetric differential amplifier circuits, a relatively wider operating frequency range is obtained.

Abstract: A recording unit (3) for recording image information and/or audio information onto a replaceable tape-shaped recording medium (10), filing units (5), (8) for filing the image information and/or the audio information which have been written onto the replaceable tape-shaped recording medium (10) by the recording unit (3), and a file information writing/reading unit (6) for writing/reading, in a non-contact state, file information of file into a random accessible memory unit (22) provided in a manner associated with the replaceable tape-shaped recording medium (10) are provided to thereby realize an information processing apparatus.

Abstract: A programmable controller and method for correcting operation of a read/write head in a disc drive having an embedded servo system in which the head is not reading correctly operates by applying a write current to the failed head only after the head is positioned over an area of a disc that does not have useful data thereon. Movement and position of the head that is not reading correctly is determined from a signal from an adjacent head. The adjacent head is used to read servo information. After the adjacent head has provided servo information and the controller repositions the adjacent head in a safe area, a write current is applied to the failed head to realign the head without the potential of adversely impacting data stored in adjacent tracks.

Abstract: Embodiments of the present invention relate to an impedance-matched write driver circuit which comprises a voltage source, a write driver circuit electrically coupled to the voltage source, a signal input coupled so as to effect the output of the write driver circuit, and an impedance matching circuit electrically coupled to the write driver circuit, wherein the impedance matching circuit is enabled to damp the output oscillations in the output of the write driver circuit. Importantly, the impedance of the impedance-matched write driver circuit is selectable by component selection or by logic. Another embodiment of the present invention is directed to a system, e.g., a magnetic disk storage unit that makes use of the write driver as described herein.

Abstract: The present invention provides techniques for generating an intense magnetic pulse very quickly. The present invention includes a device that drives high current through a write head, which generates a burst of magnetic flux that in turn generates a high-intensity fringing field. To rapidly build up the current through the write head, the write head is coupled to a high voltage source. A switching circuit prevents current from flowing in the write head. In response to a signal from a control circuit, the switching circuit provides a path for current to flow through the write head. Current flow through the write head rises rapidly, which causes a burst of magnetic flux and generates a high-intensity magnetic fringing field. The high-intensity fringing field may be used to write to a magnetic medium.

Abstract: A technique and associated circuitry are provided for measuring a buffered write head voltage, and measurement of thin-film write head DC head voltage in a disk-drive, along with a procedure for calibrating/optimizing the write current amplitude based on the measurement of the buffered write head voltage. A write driver includes a terminating resistor, coupled to the write element of a transducer head in a disk drive, wherein controlling the write current of the write driver includes the steps of measuring the resistance RW of the terminating resistor; measuring the resistance RC of the write element; and generating the write current amplitude based on the resistances RC and RW.

Abstract: A write drive circuit (40) for a hard disk drive selectively providing a current mode operation for high speed data write of a single channel, and selectively providing a voltage mode operation during a servo write operation. A central buffer has a first circuit (50) providing a current mode drive signal to a head during a single channel write operation, and a second circuit (52) providing a voltage mode drive signal for multi-channel servo write operation. The outputs of both circuits (50, 52) is provided over a common differential connection (T1) feeding a pre-driver circuit (70) adapted to drive one or many heads, as determined by head select control lines (72). The circuit provides >1.6 Gb/s data write speed in single channel write operation, and has an architecture utilizing only two signal lines for four channels.

Abstract: In a magnetic recording writing circuit, a current having a higher level than a write current is supplied for a period of time during rise and fall of the write current, and a current having a lower level than the write current is supplied for a period of time during overshoot at the rise and fall of the write current. Accordingly, the write current can recover quickly from overshoot.

Abstract: Deterioration in recording performance immediately after the start of recording in a magnetic recording apparatus due to the contraction of the magnetic head element in low atmospheric temperatures is prevented, thus ensuring a stable recording performance irrespective of the ambient temperature. Upon reception of a recording command for first data from a host device, second data already recorded in the same track as that of a data area where information is to be recorded is read and then stored in a memory. Dummy data is then recorded in the data area on the track, and then the first and second data stored in the memory is recorded. Magnetic disc apparatuses for car navigation systems, where stable operation under low temperatures is required, can be provided at low cost.

Abstract: A disc drive storage system and device is provided in which distortion in a drive signal due to a mismatch between a signal source impedance and a write head impedance is minimized. A write head that writes on a disc surface and a signal source that provides a drive signal to the write head are coupled by an electrical interconnect path. A connection device that minimizes the mismatch between the signal source impedance and the write head impedance is introduced in the electrical interconnect path. In addition, a method of coupling a signal source to a write head in a disc drive storage system is provided.

Abstract: A system and method enable boosting a bias applied to a load so as to facilitate reversing the direction of the bias applied relative to the load. The amount of boosting provided to facilitate reversing the bias polarity, depends on a substantially fixed boost voltage, which can be programmable. Thus, by setting the boost voltage to a predetermined voltage improved performance can be achieved, including, for example, improving the rise and/or fall times of bias current applied to an inductive load.

Abstract: A technique for presenting an optimally timed control signal to an upper H-switch driver in a fashion capable of achieving a very fast transition of the current in the inductive recording head. The technique also provides a current boost during the transition while resulting in minimized power consumption at other times.

Abstract: A recording/reproducing apparatus capable of switching over among a plurality of heads with high precision, wherein the apparatus is provided with: a recording/reproducing unit for recording/reproducing signals onto/from a recording medium with a plurality of heads; a generating unit for generating control data for controlling the recording/reproducing unit; and a transmitting unit for transmitting control data generated by the generating unit to the recording/reproducing unit, wherein priority is given in transmission to data for controlling the switching of the plurality of heads over other data.

Abstract: A disc drive includes a base and a disc rotatably attached to the base. The disc drive also includes an actuator assembly rotatably attached to the base and a device for moving the actuator assembly. The actuator assembly includes an arm carrying a write head in a transducing relationship with respect to the disc. The write head further includes a preamp current driver circuit. A data pulse circuit is operatively coupled to the preamp current driver circuit to provide a write current impulse based on an input data pattern. The preamp current driver circuit further includes a plurality transistors to receive the write current impulse and provide a sequence of write current impulses of opposite polarity to the write head for effecting magnetic recording on the disc of the disc drive based on the input data pattern.

Abstract: A digital temperature monitor (DTM (24) includes a proportional-to-absolute temperature (PTAT) sensor (44) and reference circuit (48) coupled to the inputs of a comparator (42). The DTM (24) monitors the temperature of adjacent and/or proximate integrated circuitry. The method includes the steps of providing a reference signal to the comparator (42), increasing the reference signal voltage, and determining the temperature of an integrated circuit by determining when the reference signal is greater than the PTAT sensor (44) output voltage. The DTM (24) may be implemented as part of a hard-disk drive preamplifier circuit (22).

Abstract: A system and method provide overshoot protection to facilitate driving a load by output circuitry in response to a transition from a first operating mode to a second operating mode. The overshoot protection occurs by masking an input bias from biasing the output circuitry for an initial part of the second operating mode based on a transition to the second operating mode, and then allowing the input bias to bias the output circuitry in a desired manner in a subsequent part of the second operating mode.

Abstract: A magnetic recording and reproducing apparatus includes a R/W signal processor having a write data generator arranged to be of an interleave system and transmitting/receiving data to/from the R/W amplifier via a plurality of signal lines. In addition, the R/W amplifier has a compound circuit provided for the write data of the interleave system from the R/W signal processor and is formed as an integrated circuit, moreover, a ½ prescaler is provided at the output of the write data generator, making transmitting and receiving write data in NRZI CODE.

Abstract: A write output driver with internal programmable pull-up resistive devices is disclosed. The write output driver provides an integrated output driver circuit configurable to provide near end transmission line termination. The output driver is configured to provide transmission of a high-speed signal with increased frequencies over prior output drivers. The output impedance of the output driver is programmable and maintained substantially constant, despite ambient fluctuations. An internal bias signal generator is provided to control the impedance of the output driver.

Abstract: A write driver circuit selectively provides write current through a write head in first and second opposite directions. First and second active devices are driven with first and second pre-drive signals. Third and fourth active devices are driven with third and fourth pre-drive signals. First and second pull-up resistances are provided respectively between the first and second active devices and a fixed voltage, and third and fourth pull-up resistances are provided respectively between the third and fourth active devices and the fixed voltage. A first capacitor is connected between the first active device and an intermediate point of the third pull-up resistance, and a second capacitor is connected between the second active device and an intermediate point of the fourth pull-up resistance.

Abstract: A set of coils wind around a magnetic core in a thin film magnetic head. Current supplying circuits are separately connected to the individual coils. The individual coils get shorter in the overall length as compared with the case where a set of coils consist of a single conductor. The impedance of the coils can be reduced. The reduction in the impedance enables the flow of the electric current to be established in a moment within the coils. The magnetic field of a sufficient intensity can be generated in a moment. Magnetization of a sufficient intensity can thus be established on a magnetic recording medium even when the frequency of a signal for recordation gets higher.

Abstract: The present invention relates to a structure of a magnetic recording and reproducing apparatus including a flexible substrate for transmission and reception of signals, and provides a structure of a magnetic recording and reproducing apparatus capable of preventing deterioration of the transmission characteristic, without increasing the cost, by suppressing the capacitance generated between the signal lines and the shield layer. The magnetic recording and reproducing apparatus according to the present invention includes: a flexible substrate 1 on which a plurality of signal lines 2 for transmitting and receiving signals from and to external circuits and grand lines 3 are formed and a shield layer 4 formed to face the signal lines 2 and said grand lines 3, wherein areas of the portion of the shield layer 4 covering each pair of signal lines 2a, 2b among the plurality of signal lines 2 are different from one another.

Abstract: A circuit (30, 40) and method for detecting faults of a write head (18) of a hard-disk drive system (70). A first resistor R1 and a second resistor R2 are coupled to coil L of write head (18). A transistor Q1 is coupled to a common node of resistor R1 and R2. Current I0 is applied to the coil L, and voltages Vab and Vac across the nodes at either end of resistors R1 and R1 are analyzed in order to detect faults on write head coil L. The detection is performed during a quiet mode of the hard-disk drive system (70), so the fault detection is frequency-independent. Open faults are distinguishable from short-to-ground faults by the write fault detection circuit (30, 40).

Abstract: A write amplifier circuit in a magnetic storage system has a cross coupling circuit and an active damp circuit to supply an improved write current to the head writing the data onto the media within the magnetic storage system. The inclusion of the cross coupling circuit decreases a rise time and a fall time associated with the write current. The active damp circuit reduces the undershoot and ringing of the write current. Thus, the write amplifier circuit is suitable for high speed data storage writing applications requiring minimal distortion of the data written to a magnetic medium. The write amplifier circuit achieves these improvements in the waveform of the write current by incorporating circuit elements and using both a negative feedback path and a feedforward path.

Abstract: A write head circuit is provided having improved transient and steady state response. The circuit includes a dynamically coupled damping circuit that is coupled to the write head during transient periods of a write signal to substantially reduce or eliminate overshoot generated by a write head cable. During steady state or data writing periods, the damping circuit is decoupled from the write head to prevent unnecessary loading of the write head. In preferred embodiments, the damping circuit includes a resistor in series with a capacitor, and the damping circuit is coupled in parallel to the write head. The resistor substantially reduces the overshoot of a write signal supplied to the write head, while the capacitor decouples the resistor from the write head during steady state or data write periods.

Abstract: A disc drive storage system and device is provided in which uncharacteristic behavior of a signal source caused by having to drive a very low impedance due a common mode component of the drive signal is eliminated. A write head that has a first and second end writes on a disc surface. A signal source provides a drive signal to the write head. The drive signal has a differential signal component and a common mode signal component. An electrical interconnect path couples the write head and the signal source. The electrical interconnect path provides a return path for the differential signal component and an open circuit for the common mode signal component. A common mode termination network with a first node, second node and a center tap is included. The first node is connected to the first end of the write head, the second node connected to the second end of the write head and the center tap connected to ground to provide a return path for the common mode signal component.

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: A preamplifier system is provided for connection through an interconnect to a read head. The interconnect has a characteristic impedance associated therewith. The preamplifier system includes an amplifier circuit having an input for connection to the interconnect. The amplifier circuit amplifies an input signal carried from the read head through the interconnect, yielding an amplified input output signal. A feedback resistance is connected between the amplified output signal and the input of the amplifier circuit. The feedback resistance has a value selected to provide an effective input impedance of the preamplifier system to match the characteristic impedance of the interconnect.

Abstract: A disk drive system including a write circuit for controlling current through a magnetic write head includes an H-switch circuit and a pulse-mode power supply circuit. The H-switch circuit controls direction of current through the magnetic write head. The pulse-mode power supply circuit is connected to the H-switch circuit for providing a higher voltage pulse at a beginning of a switching event of the H-switch circuit to accelerate a change in direction of current through the write head, followed by a lower voltage until a next switching event.

Abstract: A main controller controls the current in an overshoot part included in the write current supplied from a write driver to a head in accordance with write data via an overshoot controller in accordance with the temperature detected by a temperature sensor.

Abstract: A disk drive system including a write circuit for controlling current through a magnetic write head includes an H-switch circuit and a charge-pumping circuit. The H-switch circuit controls direction of current through the magnetic write head. The charge-pumping circuit is connected to the H-switch circuit for storing energy during a first state of the H-switch circuit, and delivering energy upon switching from the first state to a second state of the H-switch circuit to accelerate a change in direction of current through the write head.

Abstract: A system and method of controlling the operation of linear variable-gain amplifiers to allow for such linear variable gain amplifiers to have a wider operating range at high current levels, control inputs for selectable gains and improved low-voltage operation. In a first mode, the amplifier includes an additional source of current to allow for an enhanced operating range. In a second embodiment, the amplifier includes a plurality of selective resistive levels and a selection system which allows the selection of one of the resistive levels which, in turn, controls the gain range of the amplifier system of the present invention. A third embodiment of the present invention illustrates the use of an amplifier system useful for a low voltage input signal to reduce errors caused by variations in the base to emitter in the two transistors providing the amplification.

Abstract: A plurality of data bits are magnetically recorded on a medium (such as a magnetic disk in a disk drive system) by creating a write bubble region encroaching on the medium. The write bubble region has a magnetic polarity that is reversed in a pattern that corresponds to the values of the data bits being recorded on the medium. The timing of the reversing of the magnetic polarity of the write bubble region is adjusted by a precompensation system to ensure that the recorded data bits are evenly spaced on the medium. The timing adjustment is made by the precompensation system based on a state of at least one data bit previously recorded on the medium and on a state of at least one data bit to be subsequently recorded on the medium.

Abstract: Magneto-Resistive (MR) head read/write channel (400) provides timer (421), detector (433) and amplifier (432) to reduce the amount of time required to transition from read mode to write mode. Controller (410) issues the write command (WGATE) to signal a pending mode change from read to write mode. While read/write channel (400) remains in read mode, timer (421) begins a configurable countdown sequence, which allows Arm Electronics (430), except for a final output stage of amplifier (432), to power up in preparation for write mode. Once timer (421) has reached terminal count, signal (CHWGATE) is de-asserted, which causes write channel (422) to warm up. After warm up, write channel (422) writes serial data (WRITE DATA) to detector (433). Still in read mode, detector (433) detects the presence of WRITE DATA from write channel (422) and asserts signal (AEWGATE).

Abstract: A method and apparatus for providing adaptive drive-level compensation for amplitude and BER loss due to media thermal decay is disclosed. Specifically, in one embodiment, a disk surface having information stored thereon is provided. The information is written in the form of magnetic transitions, which are subject to thermal decay. A head is used to read the information stored on the disk surface and is biased by a bias current (or a bias voltage). A value related to the thermal decay of the magnetic transitions is determined. If the value indicates that the thermal decay has reached an unacceptable level, the bias current is increased in order to compensate for the thermal decay of the magnetic transitions. Once a bias current limit has been reached, information stored on the disk surface is rewritten.

Abstract: A mobile device is disclosed comprising a disk storage system including a disk and a head actuated over the disk, wherein the disk comprises a data area. The mobile device further comprises a motion detector for detecting a relative velocity and distance of a foreign object with respect to the mobile device. When the motion detector detects an impending impact with the foreign object, retracting circuitry within the mobile device retracts the head away from the data area of the disk.

Abstract: A method for forming a termination for a magnetic write head in which a magnetic write coil having an inner turn and an outer turn is formed on a wafer. A bottom capacitor plate for a capacitor on the wafer. A resistor having a first terminal and a second terminal is also formed on the wafer. A dielectric layer is formed over the bottom capacitor plate for the capacitor. A top capacitor plate is formed on the dielectric layer. An overpass lead is formed between the inner turn of the coil and one of the bottom capacitor plate and the top capacitor plate. The first terminal of resistor is connected to the capacitor plate that is not connected to the inner turn of the write coil. The second terminal of the resistor is connected to the outer turn of the write coil. An impedance formed by the write coil, the capacitor and the resistor substantially equals a characteristic impedance Z0 of an interconnect circuit that will be connected to the write coil.

Abstract: A method and apparatus that adjusts FIR taps based upon Viterbi margin counts. The FIR taps are adjusted by a) selecting one of N tap pairs for adjustment, b) adjusting the tap pair up one count and down one count, c) determining whether adjusting the tap pair up or adjusting the tap pair down provides a lower Viterbi margin count from the Viterbi detector and d) selecting the tap adjustment for the pair that provides the lower Viterbi margin count.

Abstract: A magnetic recording apparatus equipped with a recording circuit for generating a recording current corresponding to an input recording signal, a magnetic head, operable in response to the generated recording current, for recording, in a magnetic recording medium, data corresponding to the input recording signal, and a waveform shaping section for shaping the generated recording current such that a current value of said recording current approximates to a predetermined value while keeping thereover throughout a period corresponding to the data length. Both the recording circuit and the waveform shaping section may be mounted in an integrated form on a single microchip. The result is that the input recording signal can be transferred at high speed as measures are provided to reduce both a rise time and a fall time of the recording current.

Abstract: A mobile device is disclosed comprising a disk storage system comprising a disk and a head actuated over the disk, the disk comprising a data area. The mobile device further comprises a pressure-sensitive detector for detecting a pressure on the mobile device, and for detecting a decrease in the pressure on the mobile device indicating the mobile device may have been dropped. When the pressure-sensitive detector detects the decrease in the pressure, retracting circuitry within the mobile device retracts the head to a retracted position away from the data area of the disk.

Abstract: A voltage buffer and follower includes a single ended output, a source follower, and a current feedback loop. The current feedback loop is coupled to the source follower and to the single ended output. When two voltage followers are used in a differential configuration, the voltage followers can become part of a high bandwidth gain cell. The high bandwidth gain cell includes a first and a second source follower circuit that are coupled to the first and the second current feedback loops, respectively. The first and the second source follower circuits are further coupled to a first and a second current mirror circuit, respectively. The first and second current mirror circuits are coupled to a load, which is coupled to a common-mode feedback circuit. The common-mode feedback circuit controls a constant current source that sinks mirrored direct currents that flow through the first and the second current mirror circuits.

Abstract: A system and method of controlling the operation of linear variable-gain amplifiers to allow for such linear variable gain amplifiers to have a wider operating range at high current levels, control inputs for selectable gains and improved low-voltage operation. In a first mode, the amplifier includes an additional source of current to allow for an enhanced operating range. In a second embodiment, the amplifier includes a plurality of selective resistive levels and a selection system which allows the selection of one of the resistive levels which, in turn, controls the gain range of the amplifier system of the present invention. A third embodiment of the present invention illustrates the use of an amplifier system useful for a low voltage input signal to reduce errors caused by variations in the base to emitter in the two transistors providing the amplification.

Abstract: Catastrophic failures of a write precompensation circuit are prevented from occurring without limiting the precompensation range to a small value and the range of precompensation is extended beyond limits imposed by the duty cycle of the clock signal. Catastrophic failure of the write precompensation circuit is prevented by ORing either the input or the output of the comparator and the opposite phase of the clock. The 180 degree delayed clock forces any transitions that would otherwise have been missed. The range of a write precompensation circuit is extended by ORing the clock and the clock delayed by a time td. The extended duty cycle that results is used to generate a longer precompensation delay. A technique is also provided to maintain constant duty cycle over a broad range of data rates.

Abstract: A write drive circuit (40) for a hard disk drive selectively providing a current mode operation for high speed data write of a single channel, and selectively providing a voltage mode operation during a servo write operation. A central buffer has a first circuit (50) providing a current mode drive signal to a head during a single channel write operation, and a second circuit (52) providing a voltage mode drive signal for multi-channel servo write operation. The outputs of both circuits (50, 52) is provided over a common differential connection (T1) feeding a pre-driver circuit (70) adapted to drive one or many heads, as determined by head select control lines (72). The circuit provides >1.6 Gb/s data write speed in single channel write operation, and has an architecture utilizing only two signal lines for four channels.

Abstract: A voltage-mode boosting write driver circuit (40) having a pair of voltage boosting PMOS transistor sets (44, 46) coupled to a high current H-switch (42). One set (44) of the boosting PMOS transistors correspondingly pulls output pin HY high, while the other transistor set (46) correspondingly pulls output pin HX high and the other output pin HY low thereby significantly improving the head voltage swing, and also achieving a faster slew rate. Moreover, resistors (R3, R4) of the H-switch are both matched to each other and impedance matched to a flex cable (T0) interconnection impedance, which interconnection is coupled to the thin film head, to thereby eliminate signal reflection such that the write current (Iw) settles quickly with minimum ringing to achieve a high data rate. Moreover, less power dissipation and smaller number of devices used are achieved by making use of existing transient currents of the pre-driver emitter follower stage.

Abstract: The present invention is a method and system to optimize a write channel in a hard disk drive. The method comprises providing a disk having a at least one side with a plurality of tracks, and selecting a target track from the plurality of tracks. Data is written at least once on a predetermined plurality of tracks adjacent to either side of the target track and on the target track. Data is also written a predetermined number of times on tracks immediately adjacent to the target track. Data written on the predetermined plurality of tracks adjacent to either side of the target track and on the target track is then read. The process then determines if a number of errors on the tracks is greater than a predetermined criteria, if so, a write current value of the write channel is decreased, otherwise the write current value is increased.