Texas Instruments Corporation

Vtc Inc.

Douglas Warren Dean

Indumini W Ranmuthu

Shengyuan Li

Craig Matthew Brannon

Tuan V Ngo

Jeremy Robert Kuehlwein

Raymond Elijah Barnett

Robert John Schuelke

John Anthony Schuler

A damping circuit having an input terminal and an output terminal is described. The damping circuit comprises a driver having an input and an output; an RC circuit coupled between the input terminal and the output; and a resistor coupled between the output and the output terminal, wherein the RC circuit delays passing a signal from the output terminal to the input terminal and a low impedance associated with the driver generally reduces ringing.

Laser diode driver damping circuit

A disk drive preamplifier integrated circuit. The integrated circuit comprises a differential output driver configured to drive readback data to an output load, wherein the output driver comprises a differential mode filter configured to filter alternating current of an on-chip power supply.

Disk drive preamplifier R/C differential mode filter of power supply

Disk drive pre-amplifier output stage circuitry is presented including a high pass input filter for removing DC offsets from differential read data signals and providing an input to AB drivers of the output stage, in which an offset test circuit selectively drives the high pass filter output nodes according to the offset at the filter input to facilitate measurement of the preceding circuit offset at the driver output terminals, and a common mode regulator circuit regulates common mode voltages at the first and second driver output nodes to a predetermined value in read and write modes.

Pre-amplifier output stage with integrated test buffer

Various apparatuses, methods and systems for damping a current driver are disclosed herein. For example, some embodiments provide an apparatus for supplying current, including an output transistor connected between a voltage supply and a current output, and an active clamp connected between the current output and a current sink. The active clamp is adapted to connect the current output to the current sink when a voltage at the current output reaches a predetermined state relative to a voltage at a control input of the output transistor.

Current driver damping circuit

An optical disk drive system associated with a laser diode is described. The optical disk drive system comprises a current generator for receiving input signals; a current switch coupled to receive timing signals; a current driver coupled to receive output signals from the current switch and the current generator, the current driver further comprising a driver with wave shape control selected from the group consisting of a laser diode read driver and a laser diode write driver, wherein the driver with shape control is operative for transmitting at least one output signal that is a scaled version of at least one of the output signals received from the current generator, wherein the current driver is operative for transmitting at least one output signal driving the laser diode.

Laser diode driver with wave-shape control

Laser diode write driver feedback, current mirror, and differential-pair circuitry

An apparatus is provided. The apparatus includes a lasing element, a laser driver and logic. The laser driver is configured to drive the lasing element at multiple current levels, and the laser driver includes a switching network, multiple direct current (DC) loops, and an output circuit. The switching network receives a differential input signal, and each DC loop is coupled to the switching network. The output circuit is also coupled to the lasing element, and the logic is coupled to each of the DC current loops, where the logic selects one or more of the DC loops in each (of several) modes. Each mode generates one or more output lasing currents for the lasing element that corresponds to a one or more of the current levels in response to the differential input signal.

Laser driver

A laser diode read driver includes a first transistor producing a first voltage in response to receiving a first current signal. A transconductor has a first input coupled to receive the first voltage and produces a second current signal in response to differences between signals received on the first input and a second input. A second transistor is coupled to the second input and produces a third current signal in response to receiving the second current signal. A third transistor is coupled to the second transistor and the second input and produces an output current signal in response to receiving the third current signal. The first transistor is scaled to the first transistor by the inverse of a gain factor. First and second resistors are coupled between the first and third transistors and a low voltage supply, and are scaled to each other by the gain factor.

Laser diode read driver

A laser diode write driver is described. This laser diode write driver comprises: a feedback loop coupled for receiving an input current signal, the feedback loop operative for reaching a steady state and comprising a Class AB driver in series with a Class A driver, wherein the feedback loop transmits a first current signal; a current mirror adapted to receive the first current signal, the current mirror operative for replicating the first current signal and transmitting a second current signal; a differential device adapted to receive the second current signal, the differential device operative for steering current in at least one direction and transmitting a first voltage signal; a second class AB driver adapted to receive the first voltage signal and transmit a first drive signal, a second Class A driver adapted to receive the first drive signal and transmit a second drive signal; and an output device coupled to the second drive signal and operative for transmitting a driver output signal that drives the light source in response to receiving the second drive signal.

Laser diode write driver

A first transistor produces a first voltage in response to a first current signal. A first resistor is coupled between the first transistor and a low voltage supply. A transconductor has a first input receiving the first voltage and producing a second current signal in response to differences between signals received on the first input and a second input. A second transistor is coupled to the second input and produces a third current signal in response to the second current signal. A third transistor, coupled to the second transistor and the second input, produces an output current signal in response to the third current signal. The first transistor is scaled to the third transistor by the inverse of a gain factor. A second resistor is coupled between the third transistor and a low voltage supply. The first resistor is scaled to the second resistor by the gain factor.

A preamplifier circuit for a disk drive system is disclosed. The preamplifier circuit has first and second inputs that sense the voltage on either side of a magnetoresistive (MR) head element, which presents a varying resistance according to the localized magnetic field at a nearby disk surface. The preamplifier circuit includes a programmable input impedance circuit, which presents an impedance in parallel to feedback impedance at each of the first and second inputs. The parallel impedance presented by the programmable input impedance circuit is controlled by controlling a current source in the programmable input impedance circuit; a higher current results in a lower input impedance.

Magnetoresistive head preamplifier circuit with programmable input impedance

One embodiment of the invention includes an amplifier system. The amplifier system comprises an amplifier stage configured to receive an input signal at an amplifier input and to provide an amplified output signal. The amplifier system also comprises a programmable input impedance stage comprising a plurality of transconductance stages. At least one of the plurality of transconductance stages can be selectively activated based on a selection signal, the at least one of the activated transconductance stages providing current through the amplifier input that adjusts an impedance associated with the amplifier input based on the amplified output signal.

Growing community of inventors

Eagan, MN, United States of America

Douglas Warren Dean