Implementing spin torque oscillator power-on oscillation checker using ramped STO bias differentiator in microwave-assisted magnetic recording (MAMR) hard disk drives
First Claim
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1. A method for implementing a spin-torque oscillator (STO) oscillation checker for microwave assisted magnetic recording (MAMR) hard disk drives (HDDs) comprising:
- applying a changing STO bias current to a spin-torque oscillator (STO);
using a differentiator circuit coupled to the STO, monitoring STO resistance responsive to the applied changing STO bias current to identify a STO resistance change and STO oscillation; and
using the identified STO oscillation to ensure stable MAMR HDD write operation.
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Abstract
A method, apparatus, and system are provided for implementing a power-on spin-torque oscillator (STO) oscillation checker to monitor STO resistance to identify STO oscillation with microwave assisted magnetic recording (MAMR) hard disk drives (HDDs). A changing bias current is applied to the STO in the presence of constant write drive current. The STO bias current is changed to observe sudden changes in STO resistance monitored using a differentiator circuit to identify STO oscillation, used to ensure stable MAMR HDD write operation.
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Citations
20 Claims
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1. A method for implementing a spin-torque oscillator (STO) oscillation checker for microwave assisted magnetic recording (MAMR) hard disk drives (HDDs) comprising:
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applying a changing STO bias current to a spin-torque oscillator (STO); using a differentiator circuit coupled to the STO, monitoring STO resistance responsive to the applied changing STO bias current to identify a STO resistance change and STO oscillation; and using the identified STO oscillation to ensure stable MAMR HDD write operation. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for implementing a spin-torque oscillator (STO) oscillation checker for microwave assisted magnetic recording (MAMR) hard disk drive (HDDs), comprising:
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a controller; at least one disk;
said disk including a disk media for storing data;a spin-torque oscillator (STO) for microwave assisted magnetic recording (MAMR); the spin-torque oscillator (STO) oscillation checker comprising a STO bias current source applying a changing STO bias current to the spin-torque oscillator (STO); a differentiator circuit coupled to the STO, said differentiator circuit monitoring STO resistance responsive to the applied changing STO bias current to identify a STO resistance change and STO oscillation; and said controller using the identified STO oscillation to ensure stable MAMR HDD write operation. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A system for implementing a spin-torque oscillator (STO) oscillation checker comprising:
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a microwave assisted magnetic recording (MAMR) hard disk drive (HDD), said MAMR HDD comprising a controller; at least one disk;
said disk including a disk media for storing data;a spin-torque oscillator (STO) for microwave assisted magnetic recording (MAMR); the spin-torque oscillator (STO) oscillation checker comprising a STO bias current source applying a changing STO bias current to the spin-torque oscillator (STO); a differentiator circuit coupled to the STO, said differentiator circuit monitoring STO resistance responsive to the applied changing STO bias current to identify a STO resistance change and STO oscillation; and said controller using the identified STO oscillation to ensure stable MAMR HDD write operation. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification