Differential laser diode driver apparatus and systems

Abstract

Apparatus and systems create differential drive signals suitable for HAMR data recording. A laser diode differential driver provides heating current pulses at a time Φ1. The pulses energize a laser diode to pre-heat the magnetic medium to be written. Some embodiments duplicate portions of the laser diode circuit architecture to create a magnetic write head differential driver. The write head driver provides write current pulses to a magnetic write head in one direction with θ1 timing and in the opposite direction with θ2 timing. Both drivers utilize sets of reference voltages capable of being switched to one terminal or the other of the element to be driven. In the laser diode case, the common mode is split between the anode and cathode sections of the driver. A feedback element is added between the cathode and anode sections to provide current accuracy independent of the electrical characteristics of the selected laser diode.

Description

TECHNICAL FIELD[0001]Structures described herein relate to semiconductor integrated circuits, including laser diode driver apparatus and heat assisted magnetic recording (HAMR) systems.BACKGROUND INFORMATION[0002]Social media and other technologies continue to drive the recording and archiving of large amounts of data, including voice, video and other high data rate files. In spite of inroads made by solid-state drive (SSD) and other non-magnetic mass storage technologies, the computer industry continues to look to the evolution of magnetic recording (so-called “HDD”) technologies to satisfy the rapidly-increasing worldwide data storage demand.[0003]One such technological evolution is a magnetic recording technique referred to as Heat Assisted Magnetic Recording (“HAMR”). Increasing storage densities require hard drive platter materials of increased magnetic coercivity. Such materials in turn require increasingly (and impractically) large magnetic fields to align the ferrous molecul...

AI Technical Summary

Benefits of technology

[0015]Although the load requirements are considerably different for the laser diode driver as compared to those of the magnetic recording head driver, embodiments of the two circuits herein are designed to be similar. Doing so results in a high degree of tracking between the heating and writing processes across bias current, temperature and process ranges.

[0016]Both drivers utilize sets of reference voltages capable of being switched to one terminal or the other of the element to be driven, whether laser diode or magnetic write head. In the laser diode case, the common mode is split between the anode and cathode sections of the driver. A feedback element is added between the cathode section output and the anode section common mode junction to provide current accuracy independent of the electrical characteristics of the selected laser diode.

Problems solved by technology

Such materials in turn require increasingly (and impractically) large magnetic fields to align the ferrous molecules below the write head and thus perform recording operations.

Structures and techniques associated with signal drivers for current-technology HDD magnetic recording head technologies may not be suitable for HAMR and other advanced technologies.

Likewise, structures and techniques associated with laser diode drivers used in current-technology optical recorders (e.g., CD, DVD, etc.) may not be suitable for HAMR and other ultra-density recording techniques.

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