Marvell International Limited

Leechung Yiu

Sehat Sutardja

Farbod Aram

Yi Cheng

Calvin Fang

William Lo

Willaim Lo

A first network device comprises first and second transformers that communicate with a second network device. A switch selectively connects power to the first and second transformers. A physical layer device communicates with the first and second transformers and includes a signal generator, a detector, and a controller that communicates with the switch, the signal generator and the detector. The signal generator generates a test signal comprising n sub-pulses, where n is an integer greater than 2. When the detector detects j pulses that are greater than a predetermined threshold, 1&#x2266;j&#x3c;n, the controller supplies power to the second network device, where j is an integer.

Method and apparatus for detecting and supplying power by a first network device to a second network device

A first network device supplies power to a second network device in communication therewith. The first network device comprises a physical layer device which includes a pulse generator to generate a test signal comprising n sub-pulses to be transmitted to the second network device, wherein in n being greater than 2. A detector is responsive to the second network device, and a controller is in communication with the detector and the pulse generator. When the detector detects j pulses which are greater than a predetermined threshold, 1&#x2266;j&#x3c;n, the controller, responsive to the detector, enables power to be transmitted to the second network device.

A high-speed transmission circuit includes an inductive head. The high-speed transmission circuit also includes a non-uniform transmission line having a variable characteristic impedance. The non-uniform transmission line is coupled between the inductive head and an endpoint node such that pulses are conducted over the non-uniform transmission line. The variable characteristic impedance is greater near the inductive head than near the endpoint node.

Write channel having a preamplifier and a non-uniform transmission line

A high speed data transmission channel, preferably embodied in a circuit for writing to a read channel for a hard disk drive, is provided. The channel includes a preamplifier writer, a non-uniform transmission line, and a head. The writer is configured to transmit pulses to the head via the transmission line at a transmission speed. Each pulse has a pulse width. Each pulse may experience interference. The writer is also configured to eliminate interference to each pulse by causing the interference to occur in a differential mode, which causes the interference to cancel out. A transmission time for each pulse is inversely proportional to the transmission speed. The non-uniformity of the transmission line may entail an exponential broadening of a trace width of the transmission line such that when the pulse width is greater than or approximately equal to the transmission time, the pulse propagates from the writer to the head substantially undistorted.

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Fremont, CA, United States of America

Leechung Yiu