Texas Instruments Corporation

Motomu Hashizume

Naoko Jinguji

Indumini W Ranmuthu

Hiroyuki Mukai

Yukoh Matsumoto

Naoko Takemoto

Jinguji Naoko

Neel Seshan

Takashi Takamizawa

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.

Resistivity sense bias circuits and methods of operating the same

A disk drive controller including a preamplifier and a controller is disclosed, in which communications between the controller and the preamplifier are carried out over at least some shared terminals and conductors. A first pair of differential lines is provided to communicate data, sensed at read/write heads of the disk drive, from the preamplifier to the controller, and a second pair of differential lines communicates data to be written to the disk drive from the controller to the preamplifier. Control signals are communicated over a serial interface between the controller and preamplifier, over the first pair of differential lines, so that serial communication can be carried out simultaneously with the writing of data from the controller to the preamplifier. Alternatively, the control signals are communicated over the second pair of differential lines, simultaneously with the reading of data from the preamplifier to the controller.

Hard disk drive preamplifier with reduced pin count

Methods and apparatus to perform hard-disk drive head proximity detection in a preamplifier are described. One example method of detecting head position in a hard-disk drive includes obtaining a read signal from a head reading information from a disk; determining a signal envelope of the read signal; comparing the signal envelope to a first threshold to produce a first comparison; filtering the signal envelope; comparing the filtered signal envelope to a second threshold to produce a second comparison; combining the first comparison and the second comparison; and determining if the combination of the first comparison and the second comparison indicates head position oscillation.

Methods and apparatus to perform hard-disk drive head proximity detection in a preamplifier

An amplifier apparatus for use with a sensor includes: (a) a first and a second amplifying circuit segment coupled with the sensor and cooperating to effect substantially balanced handling of signals received from the sensor; the first amplifying circuit segment includes a first transistor device; the second amplifying circuit segment includes a second transistor device; (b) a countercurrent unit coupled with the first and second amplifying circuit segments for receiving a first indicator signal from the first transistor device and a second indicator signal from the second transistor device; the first indicator signal represents a first parameter in the first transistor device; the second indicator signal represents a second parameter in the second transistor device; the countercurrent unit provides feedback signals to at least one of the first transistor and second transistor devices to reduce input impedance of the apparatus.

Amplifier apparatus for use with a sensor

The present invention provides a current-sense bias circuit for use with a magnetoresistive head. In one embodiment, the current-sense bias circuit includes a voltage biasing portion configured to provide a bias voltage across the magnetoresistive head thereby establishing a bias current through the magnetoresistive head. Additionally, the current-sense bias circuit also includes a current sensing portion coupled to the voltage biasing portion and configured to sense a change in the bias current based on a resistivity change of the magnetoresistive head.

Current-sense bias circuit for a magnetoresistive head and method of sensing a current therethrough

An apparatus for driving a write head in response to a data signal includes: (a) a first drive unit coupled with the write head; (b) a second drive unit coupled with the write head; and (c) a control unit coupled with the first and second drive units. The control unit receives the data signal and generates control signals to the first drive and second drive units in response to the data signal. The control signals control the first drive unit to apply a first drive signal to a first write head side in a first signal polarity and control the second drive unit to apply a second drive signal to the a second write head side in a second signal polarity opposite to the first signal polarity when the data signal effects a signal excursion. The first drive signal and the second drive signal are equal in magnitude time coincident.

Apparatus and method for driving a write head

Disclosed are methods and circuits for impedance-controlled write drivers using matched impedance control circuits coupled in parallel with a magnetic write head.

Impedance-controlled write driver for low power preamp

Modem comprising a delta modulation (DM) encoder and a DM decoder which has noise-reducing capability in the demodulation of encoded binary pulse signals representative of constant amplitude signals. The DM decoder includes a 1-click delay circuit operable in conjunction with a logic circuit and an integrator to produce a demodulated output signal which is the same as the preceding signal when the input signals to the DM encoder are constant amplitude signals, thereby eliminating are substantially reducing granular noise arising from a constant analog input to the modem without requiring a special filter. The logic circuit of the DM decoder may be an exclusive NOR gate which compares the 1-clock delayed binary pulse signal with the binary pulse signal and provides a control signal output based upon the comparison. The control signal output from the exclusive NOR gate controls the output of the integrator and enables the integrator to produce a substantially noise-free demodulated output signal.

Modem with noise-reducing decoder in demodulation of encoded binary

A read only memory device with a matrix of series connected FET's addressed with X and Y decoding, a control switch between the output line and a voltage source operant to connect or not the voltage source to the output line in response to a control signal phi, and a second control switch, responsive to the same signal phi, provided between ground and each string of series connected FET's.

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Tokyo, Japan

Motomu Hashizume