Differential current-mode driver for microwave assisted magnetic recording

A hard-disk drive system that facilitates a fast transition during microwave-assisted magnetic recording (MAMR) magnetic recording, the hard-disk drive system comprising:

• a write head employing a MAMR sensor;
• and
• a current-mode (iMode) driver circuitry configured to drive a controlled differential bias current through a field-entry terminal and a field-exit terminal of the MAMR sensor, the iMode driver circuitry comprising:
• a driver circuit configured to provide a controlled differential bias current, the driver circuit having separate source and sink output terminals through which the MAMR sensor receives the controlled differential bias current;
• and
• a common-mode feedback (CMFB) loop coupled to the field-entry and field-exit terminals of the MAMR sensor, the CMFB loop forming a feedback pathway with the driver circuit, the CMFB loop configured to detect common-mode voltage (CMV) and adjust the controlled differential bias current to maintain CMV regulation of the MAMR sensor.

A method that facilitates a fast transition during microwave-assisted magnetic recording (MAMR) magnetic recording, the method comprising:

• providing, by a driver circuit, a controlled differential bias current to a MAMR sensor of a magnetic media read/write channel;
• maintaining, by a common-mode feedback (CMFB) loop coupled to field-entry and field-exit terminals of the MAMR sensor, a common-mode voltage (CMV) regulation of the MAMR sensor;
• and
• switching the controlled differential bias current through the MAMR sensor with:
• a rise time of ten nanosecond or less;
• and
• a fall time of ten nanoseconds or less.