Abstract: Electronic circuitry and methods are disclosed for monitoring a portion of a write driver, for example, a steady state value of a write driver of a hard disk drive preamplifier. Based on a result of the monitoring, a condition, such as a fault, can be detected in the write driver. For example, apparatus for monitoring a write driver of a disk drive system comprises a comparator circuit coupled to an output of the write driver and configured to compare a value present at the output of the write driver with a reference value such that at least one condition associated with the write driver is detectable as a result of the comparison of the write driver output value and the reference value.

Abstract: Resistivity sense bias circuits are described herein. An example resistivity sense bias circuit for use with a magnetoresistive read head includes a current biasing portion configured to provide a bias current across the magnetoresistive read head thereby establishing a bias voltage across the magnetoresistive read head, a resistivity sensing portion coupled to the current biasing portion and configured to sense a change in the bias current based on a resistivity change of the magnetoresistive read head, and a voltage source to provide the bias voltage and to adjust the bias voltage in response to the resistivity change of the magnetoresistive read head.

Abstract: Apparatuses and methods are provided for adaptively updating a target for a recording channel, such as a magnetic recording channel. In some embodiments, a read channel apparatus is provided which includes data path modules and adaptive path modules. The data path modules estimate user information from a recording channel, and the adaptive path modules adaptively update the target taps of the recording channel. The adaptive path modules may use a linearly constrained least-mean square (LC-LMS) algorithm to determine the amount and direction of each tap update, where the linear constraint may be a maximum phase or a mixed phase constraint. The adaptive path modules may operate independently of and be decoupled from the data path modules.

Abstract: A hard disk drive that stores data on a disk. An overshoot duration is used to write data onto the disk. The value of the overshoot duration is a function of the data rate, which can vary for different areas of the disk. For example, the data rate can be higher at an outer diameter of the disk than at an inner disk diameter. The overshoot duration can therefore be different when writing data at the outer diameter than the duration used to write data at the inner diameter. The data rate can be determined by analyzing a preamble of the data written onto the disk.

Abstract: A disk drive is disclosed comprising control circuitry operable to calibrate a write current parameter. A write current is initialized to an initial write current INIT_Iw, and an overshoot is initialized to a maximum MAX_OS. The write current is swept from INIT_Iw to a maximum write current MAX_Iw while writing and reading data from a target track to measure a first quality metric. A second quality metric associated with wide track erasure is also measured. A quality of the write operations is determined in response to the first and second quality metrics. When the quality of the write operations does not exceed a threshold, at least one of the MAX_Iw and MAX_OS is decreased and the process is repeated. Otherwise, the write current is swept from a minimum write current limit MAX_Iw to the adjusted MAX_Iw for a plurality of tracks to find an optimal write current for each track.

Abstract: A signal conversion circuit includes: an input circuit that rejects common mode inputs and is configured to receive a differential input signal and shift a first bias of the differential input signal to produce a single ended intermediate signal with a second bias; and an amplifier circuit configured to amplify the single ended intermediate signal to produce an amplified signal. The input circuit can include: first and second transistors with drains configured to couple with a supply voltage, and gates of the first transistor and the second transistor are configured to receive the differential input signal; a first resistor coupled to a source of the first transistor and a drain of a third transistor; and a second resistor coupled to a source of the second transistor and a drain of a fourth transistor; where the third transistor and the fourth transistor are connected in a current mirror configuration.

Abstract: A method of setting up a pre-amplifier for a hard disk drive and a hard disk drive incorporating the method. A serial interfacing mode of the pre-amplifier is checked by writing and reading data to/from the pre-amplifier. A chip ID of the pre-amplifier is checked and a vendor of the pre-amplifier is identified using the chip ID. Default values of the pre-amplifier stored in a ROM and adaptive codes of the pre-amplifier are automatically downloaded to a register of a hard-disk controller, simplifying the pre-amplifier installation and reducing errors which may occur during manual installation of the pre-amplifier.

Abstract: A write driver system includes a logic circuit including first switching devices which receive input write signals and generate control signals. A plurality of predriver circuits includes second switching devices and generates drive signals based on the control signals. A write drive circuit includes third switching devices and generates write drive signals based on the drive signals. The third switching devices have higher threshold voltages than the first and second switching devices.

Abstract: Provided is a method of increasing recording density and a control apparatus for increasing the recording density. The method includes applying a recording current corresponding to a recording signal to a magnetic head of a hard disc drive (HDD), and limiting a current value being applied to the magnetic head to a critical value when the recording current reaches the critical value. In the method, a rising time is reduced by using an overshoot recording current and the recording current is limited to a critical value when an actual recording current reaches the critical value. Thus, write track widths (WTWs) can be reduced at a low recording frequency, thereby increasing tracks per inch (TPI).

Abstract: Two pass writing system and method for patterned media. In a first step, a write head of a hard disk drive writes with a strong write field. In a second step, a write head of the hard disk drive writes with a weak field. In this manner, magnetic islands of patterned media are written in the first step. In the second step, only those magnetic islands with a low switching field are written.

Abstract: A write driver circuit includes a first write driver that communicates with a first node of a write head. A first feedback path communicates with a control input and an output of the first write driver. The first feedback path includes a first resistance connected between the output of the first write driver and the control input of the first write driver. A second write driver communicates with a second node of the write head. A second feedback path communicates with a control input and an output of the second write driver. The second feedback path includes a second resistance connected between the output of the second write driver and the control input of the second write driver.

Abstract: Various embodiments of the present invention provide systems and methods for write pre-compensation. For example, various embodiments of the present invention provide systems for on-the-fly estimation of write pre-compensation values. Such systems include a magnetic storage medium, a read/write head assembly disposed in relation to the magnetic storage medium, and an analog to digital converter that receives an analog signal from the read/write head assembly corresponding to a data set stored on the magnetic storage medium and provides a series of digital samples corresponding to the data set. The storage devices further include a read data processing circuit that receives the same series of digital samples and provides a user data output, and a pre-compensation value calculation circuit that receives the series of digital samples and provides an updated write pre-compensation value.

Abstract: Circuits, systems, and methods for generating bias for a magneto-resistive (MR) sensor in a magnetic storage device. The circuits generally include an amplifier having an input coupled to a magneto-resistive (MR) sensor, a feedback resistive element having an output coupled to the MR sensor, and a feedback control circuit having a first input coupled to an output of the amplifier, an output coupled to an input of the feedback resistive element, and a second input coupled the output of the feedback resistive element, wherein the feedback control circuit is configured to provide a bias current to the MR sensor through the feedback resistive element. The methods generally include amplifying a signal from the MR sensor to produce an amplified signal, producing a feedback signal from the amplified signal, the feedback signal having a predetermined bias characteristic, and applying the feedback signal to the MR sensor.

Abstract: One embodiment of the invention includes a disk-drive write head fault detection system. The system includes an output stage configured to generate a monitored current through the disk-drive write head. The system also includes an open-circuit fault detector configured to compare a magnitude of a first reference current with a magnitude of the monitored current to detect an open-circuit fault condition associated with the disk-drive write head. The system further includes a short-to-ground fault detector configured to compare a magnitude of a second reference current with the magnitude of the monitored current to detect a short-to-ground fault condition associated with the disk-drive write head.

Abstract: Baseline wander is removed. A first decision signal is generated from an input signal using a first detector. Baseline wander associated with the input signal is estimated using the first decision signal. The estimated baseline wander is removed from the input signal. A second decision signal is generated from the input signal with the baseline wander removed using a second detector.

Abstract: Embodiments of the present invention reduce lowering of a recording current and a recording magnetic field that might occur upon execution of write pre-compensation for compensating the NLTS according to a perpendicular magnetic recording method. According to one embodiment, the recording current overshoot is increased for recording a high NLTS recording data pattern. The read signal quality is improved, thereby a highly reliable magnetic disk can be provided.

Abstract: A read-channel module includes a variable-gain amplifier (VGA) module, an analog-to-digital converter (ADC) module, an amplitude measuring module, a gain adjusting module, and a zero phase start (ZPS) module. The VGA module has a variable gain, amplifies input signals, and generates amplified signals. The ADC module converts the amplified signals from analog to digital format and generates samples. The amplitude measuring module receives N of the samples and measures amplitudes of the N samples, where N is an integer greater than 1. The gain adjusting module communicates with the amplitude measuring module and selectively adjusts the variable gain of the VGA module based on the amplitudes. The zero phase start (ZPS) module communicates with the amplitude measuring module, receives the samples, and selectively generates phase information from the samples based on the amplitudes.

Abstract: A preamplifier and method writes data synchronized with the passing of a write head in a magnetic storage device over bit islands in discrete patterned recording media. The preamplifier contains a write pre-driver that conditions write data, a synchronization circuit that accepts a delay offset value and a write clock and produces a delayed clock, and a write output driver that is gated by the delayed clock to produce write pulses for magnetizing the bit islands. Gating the write output driver using the delayed clock results in more accurate synchronization than delaying the write data into the preamplifier due to the reduction of the overall length and variability of interconnects and transistors in the intervening circuitry.

Abstract: Methods of generating a write current in response to a write command include generating a reverse preshoot write current having a polarity opposite to a polarity for generating a magnetic transition corresponding to the write command, and then generating a write current to effect the magnetic transition corresponding to the write command. The write current may be used for writing data to a storage disk of a disk drive that includes a write head configured to apply a magnetic field to the storage disk responsive to write currents. A preamplifier circuit includes a write current generator configured to receive a write current command and configured to generate, responsive to the write current command, a reverse preshoot current having a first polarity that is opposite a second polarity for generating a magnetic transition corresponding to the write command.

Abstract: A sample and hold circuit is disclosed that provides longer hold times. The sample and hold circuit can be used in a disc drive to provide improved read-to-write and write-to-read mode transitions. The sample and hold circuit has an input and an output, and includes at least one capacitive element for retaining a charge. The capacitive element is connected to a node between the input and the output. The sample and hold circuit includes at least one input switch to selectively connect the capacitive element to the input and at least one output switch to selectively connect the capacitive element to the output. In addition, an amplifier is connected to the node and has an offset voltage. In this manner, a voltage drop across at least one of the input and output switches is limited to the offset voltage.

Abstract: A gain controller for a gain loop of a read channel includes a comparator circuit, an accumulator circuit, and a function circuit. The comparator circuit determines an error between an actual sample of a read signal and a corresponding ideal sample of the read signal, and the accumulator circuit holds a gain-correction value and adjusts the gain-correction value in response to the error. The function circuit generates a gain-correction signal by performing a predetermined mathematical operation involving the gain-correction value, and provides the gain-correction signal to a variable-gain amplifier that is operable to amplify actual samples of the read signal. Because such a gain controller allows one to locate the variable-gain amplifier (VGA) after the analog-to-digital converter (ADC) in a read channel, the gain controller may significantly reduce the latency of the gain-acquisition (GA) loop or the gain-tracking (GT) loop of the read channel.

Abstract: Methods and apparatus to provide dynamically biased write drivers for hard disk drive applications are described. According to one example, a hard disk drive write system includes a drive signal generator to receive data to be written to a hard disk drive platter and to generate drive signals including a boost signal. A drive circuit is configured to receive the drive signals and to generate currents for output to the transmission line based thereon, wherein the currents include a boost current. A variable bias circuit is configured to detect the boost signal generated by the drive signal generator and to vary a bias signal provided to the impedance matching circuit based on the detection of the boost signal. In such an example arrangement, the impedance matching circuit matches impedances between the drive circuit and the transmission line in response to the bias signal provided by the variable bias circuit.

Abstract: A current mirror circuit providing a fast turn on time. A node within the circuit is held at a first voltage when the current mirror is off to permit the node voltage to quickly reach a necessary value when the current mirror circuit is turned on.

Abstract: An H-bridge driver for a disk drive system includes first and second high side switched legs and first and second low side switched legs. An inductor head for writing data to and reading data from a magnetic media is connected to form a center of the H-bridge. The system includes a voltage regulator circuit that generates a common mode regulated voltage. First and second high side logic circuits, which selectively control operation of the first and second high side switched legs, are coupled between a high reference voltage and the common mode regulated voltage. First and second low side logic circuits, which control the first and second low side switched legs, are coupled between the common mode regulated voltage and ground.

Abstract: An apparatus and method for controlling the common mode voltage across a data storage device write head. The write current is supplied by a first plurality of parallel current sources each independently activated to limit the common mode voltage generated across the write head. A plurality of parallel resistive elements responsive to current supplied by a second plurality of parallel current sources bias an output transistor that further controls the write current. Each of the plurality of parallel resistive elements and each of the second plurality of parallel current sources is also independently activated to limiting the common mode voltage generated across the write head.

Abstract: A magnetic recording method is provided where ternary data is recorded on a magnetic recording medium by forming a first area that corresponds to a first value of the data and in which a first magnetization state is continued at least during the minimum write width. A second area that corresponds to a second value of the data in which a second magnetization state is oppositely magnetized as compared with the first magnetization state is continued at least during the minimum write width. A third area that corresponds to a third value of the data in which the magnetic intensity detected by the read head corresponds to a “0.” Accordingly, the ternary data can be recorded using the characteristic that a signal having a width narrower than the detection width of the read head is not detected by the read head.

Abstract: A hard disk drive includes a disk pack having at least one disk for recording and/or storing data and a spindle motor that support and rotates the disk, a base to which the disk pack is mounted, a cover that covers an upper surface of the base, and a respective filter disposed close to each of at least one of the major surfaces of the disk and extending in the radial direction of the disk including over at least an inner peripheral region of the disk. The filter has an absorbent layer capable of absorbing particles that come in contact with it. Particles on the surface of the disk, from the inner to the outer peripheral regions of the disk, are removed by the filter when the disk is rotated and the particles are flung off of the disk. Thus, particles will not damage the magnetic head(s) of the hard disk drive nor will the particles cause errors to occur in the recording and/or reproducing of data.

Abstract: A magnetic, head in one embodiment includes a substrate; a write transducer; leads coupled to the write transducer; and a resistor coupled between one of the leads and the substrate or a common line. A magnetic storage system in another embodiment includes a cable having a characteristic impedance associated with a pair of conductors; a write signal generator coupled to the pair of conductors; at least one first device coupled to the cable in series with the write signal generator and at least one of the cable conductors, the at least one first device providing a first impedance; at least one second device providing a second impedance and coupled to a second end of the cable in series with at least one of the cable conductors and the first device; and a head having a write transducer coupled to the at least one second device.

Abstract: According to one embodiment, a storage device includes a rotary actuator, vibration detectors, an analog operation circuit, an analog-to-digital converter, and a rotation vibration compensation controller. The rotary actuator positions a head with respect to a storage medium to perform reading or writing. The vibration detectors are located substantially on both sides of the rotation center of the rotary actuator, detects rotation vibration component of a one-axis direction, and outputs a vibration detection signal. The analog operation circuit calculates a rotation vibration detection signal proportional to rotation vibration disturbance applied to the rotary actuator by differential amplification of the vibration detection signal. The analog-to-digital converter converts the rotation vibration detection signal into a digital signal and outputs rotation vibration detection data.

Abstract: Provided is a method and an apparatus for controlling a write parameter according to a voltage variation. The method for controlling the write parameter includes monitoring a voltage supplied to a pre-amplifier before performing a write operation and adjusting the write parameter supplied to the pre-amplifier based on the monitoring result. Controlling the write parameter includes reading a predetermined write parameter from a write parameter table based on the monitoring result, and adjusting the read write parameter to the write parameter which will be supplied to the pre-amplifier.

Abstract: Embodiments of the present invention provide a mixed-mode amplifier for amplifying signals in data storage devices such as disk drives. In one embodiments, a circuit for amplifying data signals comprises a magnetoresistive sensor having a bias voltage applied thereto; a signal amplifier which amplifies a signal detected by the magnetoresistive sensor having the bias voltage applied thereto; a feedback control block which is coupled to an output of the signal amplifier and outputs a feedback current used to vary a loop gain of the circuit; a bias setting circuit which outputs a bias setting current; and a transimpedance amplifier which receives the bias setting current from the bias setting block and the feedback current from the feedback control block and generates the bias voltage applied to the magnetoresistive sensor.

Abstract: Apparatus, systems, and methods implementing techniques for converting a signal. In an apparatus form, an input circuit receives a differential input signal and produces a single-ended intermediate signal. An amplifier circuit receives the intermediate signal and produces an amplified signal, and a feedback path couples the amplified signal to the intermediate signal. An inverter circuit receives the amplified signal and produces an output signal.

Abstract: A hard disk drive write driver circuit is described that can change the output impedance of the write driver by use of a lookup table of control values. A control value is selected from the lookup table by using an address based on a dynamic system variable and a program controlled value. The dynamic system variable is converted to a digital representation. The digital representation and a portion of the program controlled value are used as an address to the lookup table to select a control value. The write driver is responsive to the selected control value to control overshoot current. A method to digitally program the output impedance of a preamp write driver based on realistic operating data is also discussed. An additional approach to controlling overshoot current in a write driver through digital control of overshoot duration is also described.

Abstract: Provided are a method of improving a recording performance of a hard disk drive (HDD) by controlling write strength according to a flying height of a head and a computer-readable recording medium having recorded thereon a computer-readable program suitable for the method. The method of controlling write strength of the HDD includes calculating the flying height of the head before starting a recording operation and controlling the write strength according to the calculated flying height. Accordingly, optimal writing can be performed by the write strength according to the head flying height.

Abstract: Disclosed is a self servo-writing disk drive that pre-programs a preamplifier to improve servo-writing characteristics in writing servo sectors to a disk. The disk drive implements operations including: writing servo sectors to define track bands according to sets of write setting values wherein the preamplifier adjusts write signals utilizing a set of write setting values for each track band; reading servo variable gain amplifier values from the tracks bands; selecting a set of write setting values associated with a minimum servo variable gain amplifier value; programming the preamplifier's write settings with the selected set of write setting values; and self-servo writing the disk with servo sectors utilizing the selected set of write setting values that are pre-programmed in the preamplifier.

Abstract: A circuit is adapted to activate a writer head of a data storage media drive during both the boost periods as well as the steady state periods. The current supplied to the writer head during the boost periods exceeds the steady state current and flows between positive and negative voltage supplies so as to provide the required magnetic flux change in the inductor disposed in the write head. During the steady state periods, a switch circuit is turned on to provide a second current path across the writer head. During the steady state periods, the current flows between the positive voltage supply and the ground to reduce power consumption. The switch circuit is turned off during the boost periods.

Abstract: There is provided a magnetic disk device or the like which is capable of improving signal quality by suppressing occurrence of erasure of adjacent tracks due to spreading of a writing spot. The magnetic disk device is capable of controlling a steady state value of a write current for writing into a magnetic disk, an overshoot value, or a width thereof. The magnetic disk device comprises a VMM measurement section that measures a VMM, and a write current setting section that sets the write current, based on a value of the VMM measured by the VMM measurement section, such that a data writing spot is prevented from spreading during writing into the medium and occurrence of side erasure is prevented.

Abstract: Embodiments in accordance with the present invention provide a disk drive and a control method in the disk drive which can obtain good recording performance by amplifying the write current according to the recording method and the recording frequency. A HDD in accordance with an embodiment of the present invention comprises a write current supply section and a write head. The write current supply section generates a write signal for recording to a disk and, based on the write current, generates a write current IW. The write head records data to the disk by the write current IW. The write current supply section comprises a write channel to generate a write signal, a write driver to generate a write current from the write signal, a high frequency pattern extracting circuit to extract high frequency pattern parts from the write signal, and a write driver to generate a write current IB from the extracted high frequency pattern parts.

Abstract: A perpendicular recording system includes a summing module that has a first input that receives a read signal. A DC correction module selectively generates a DC correction signal to reduce DC offset in the read signal. The DC correction signal is output to a second input of the summing module. A detecting module compares an output of the summing module to a predetermined threshold and selectively detects Thermal Asperity (TA).

Abstract: A hard disk drive that stores data on a disk. An overshoot duration is used to write data onto the disk. The value of the overshoot duration is a function of the data rate, which can vary for different areas of the disk. For example, the data rate can be higher at an outer diameter of the disk than at an inner disk diameter. The overshoot duration can therefore be different when writing data at the outer diameter than the duration used to write data at the inner diameter. The data rate can be determined by analyzing a preamble of the data written onto the disk.

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 technique for de-gaussing the pole tips and yoke of a write transducer in a perpendicular magnetic recording system is provided. An oscillator in the read channel is configured to produce an adjustable signal pattern output to the preamplifier when a write operation ends for a given time and at a predetermined frequency, such that as the preamplifier write current decays, it decays with transitions (polarity reversals). This results in a decaying AC field being applied to the write transducer at the end of a media write operation, effectively de-gaussing it and reducing the effects of remanent magnetization remaining in the poles and yoke of the magnetic recording head after a write current is turned off. This defeats a potential pole tip lockup or yoke lockup circumstance in the magnetic recording media which can result in an inability to write further data or a possible erasure of valid data on the hard disk with which the write head is associated.

Abstract: Embodiments of the present invention provide a write-current control chip capable of effectively preventing adjacent track interference (ATI) that occurs depending on how a magnetic disk drive is used, and to provide a magnetic disk drive using the write-current control chip. In one embodiment, a write-current control chip and a magnetic disk drive using the same are provided. The write-current control chip includes: an acquisition module for acquiring the number of times of write processing in which a magnetic head writes data to a magnetic disk in the magnetic disk drive; a determination module, on the basis of the acquired number of times of write processing, for determining a write-current value used when the magnetic head writes data to the magnetic disk; and an instruction mechanism for instructing the magnetic head to write the data to the magnetic disk by use of the determined write-current value.

Abstract: An impedance matched write circuit is provided that shunts one or more matching resistors. The impedance matched write circuit includes an interconnect for connecting to a write head and at least one resistor between a control voltage and the interconnect for impedance matching to the interconnect. A transistor can be connected across the resistor to shunt current that would otherwise pass through the resistor during an overshoot mode. The transistor may be a PMOS transistor or a combination of PMOS and NMOS transistors. A gate voltage of the transistor is controlled by a source such that the transistor is turned on in an overshoot mode and turned off during a steady state mode.

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: In a data-recording mode, a driver circuit supplies a recording head with a recording current corresponding to write data. In a degaussing mode, the driver circuit supplies the recording head with a degaussing current for eliminating the residual magnetism of the head as the recording current. The degaussing current has a rising period and falling period set longer than those of the recording current supplied in the data-recording mode.

Abstract: System and method for write current drivers for inductive heads used in mass storage drives. A preferred embodiment comprises a write current circuit coupled to an inductive write head, a MOS transistor boost circuit and a matching circuit, both coupled to the write current circuit. The write current circuit provides a first current to the inductive write head, while the MOS transistor boost circuit provides a second current for a specified duration to the inductive write head when the MOS transistor boost circuit receives a control signal. The matching circuit selectively decouples a resistive element from the inductive write head when it receives the control signal. The MOS transistor boost circuit can accelerate the transition in a switching of the polarity of the write current and the matching circuit helps to reduce ringing without negatively affecting the speed of the polarity switching by decoupling when the second current is provided.

Abstract: The present invention achieves technical advantages as a preamplifier write driver (10) having a varying common-mode output voltage. This varying common-mode output voltage also adjusts the derivative of the common-mode voltage, which is proportional to the amount of current coupled onto the MR head through parasitic capacitance. Currents of a first circuit (Q0,Q3) and a second circuit (Q1,Q2) are matched to overcome process variations and modeling errors. A pair of transresistance amplifiers (16) are driven by control lines (14) to achieve these matched currents.

Abstract: A write driver (11) for a disk drive system is disclosed. The write driver (11) includes a normal H-bridge drive circuit (30) and a boost H-bridge drive circuit (32). The normal and boost H-bridge drive circuits (30, 32) are both biased from a Vcc power supply; however, system ground (GND) biases the normal H-bridge drive circuit (30), while a Vee power supply voltage, which is negative relative to system ground (GND), biases the boost H-bridge drive circuit (32). Diodes (46Y, 46X) are provided in the pull-down paths of the normal H-bridge drive circuit (30). During the boost portion of the write cycle, both of the normal and boost H-bridge drive circuits (30, 32) are on, and the pull-down current from the write head (HD) is conducted to the Vee power supply voltage. After the boost portion of the cycle, and thus after the desired overshoot current has been applied, only the normal H-bridge drive circuit (30) drives the steady-state write current, which is conducted to system ground (GND).

Abstract: A magnetic recording device capable of reducing the size of a writing circuit and the power consumption by readily adjusting the overshoot of the write current pulses is provided. Two or more transmission lines having different characteristic impedances are provided between an output driver having an impedance Zs and a magnetic head, the transmission lines are formed so that the characteristic impedances Z1, Zn?1, and Zn (n?2) thereof on the output driver side are higher than those on the magnetic recording head side (Z1>Zn?1>Zn), and the impedance Zs of the output driver is equal to or higher than the characteristic impedance Z1 of the transmission line.