Laser power monitoring in hard disk drives
AssigneeAvago Technologies International Sales Pte. Limited
InventorsScott O'Brien, Greg Starr, Andrew Krebs
Life of this patent
Estimating the term…
Abstract
Hard disk drives (HDD), preamplifiers for HDDs, and preamplifier circuits for HDDs. In an aspect, a preamplifier circuit might comprise one or more digital-to-analog converters (DAC) that can help reduce a thermal drift of a laser that assists in writing data to a storage medium of the HDD. A first DAC might skew a bias current between a laser power transducer and a temperature sensing transducer to reduce thermal drift. A second DAC might modify a differential current between two legs of the preamplifier circuit to further reduce thermal drift. In some cases, a calibration DAC can calibrate the output of the circuit.
Claims20
A laser diode preamplifier that drives a laser diode in a hard disc drive, the preamplifier comprising:
- a circuit, comprising:
- one or more inputs;
- one or more outputs;
- hardware and/or firmware logic to monitor at least one output;
- a bias-current-skewing (BCS) digital-to-analog converter (DAC) that scales a first current from at least one of the one or more inputs;
- hardware and/or firmware logic to determine a value of the BCS DAC (the “BCS DAC value”) that reduces a thermal drift of output power of the laser diode;
- and
- hardware and/or firmware logic to set the BCS DAC to the determined BCS DAC value.
A laser diode preamplifier that drives a laser diode in a hard disc drive, the preamplifier comprising:
- a circuit, comprising:
- a bias-current-skewing (BCS) digital-to-analog converter (DAC) that scales a first current from at least one of the one or more inputs;
- hardware and/or firmware logic to reduce thermal drift of output power of the laser diode by setting the BCS DAC to a determined BCS DAC value;
- a temperature compensation DAC that modifies a differential between a second current in a positive leg and a third current in a negative leg of the circuit;
- and
- hardware and/or firmware logic to further reduce the thermal drift of the output power of the laser diode by setting the temperature compensation DAC to a determined temperature compensation DAC value.
A hard disk drive, comprising:
- a storage medium;
- a write head;
- a laser diode that assists the write head in recording data to the storage medium;
- and
- a laser diode preamplifier, comprising:
- a circuit, comprising:
- one or more inputs;
- one or more outputs;
- hardware and/or firmware logic to monitor at least one output of the circuit;
- a bias-current-skewing (BCS) digital-to-analog converter (DAC) that scales a first current from at least one of the one or more inputs;
- and
- hardware and/or firmware logic to reduce thermal drift of output power of the laser diode by setting the BCS DAC to a determined value.
Dependencies are inferred from the claim text.