Apple Inc.

Vishal Varma

Sanjeev K Maheshwari

Lizhi Zhong

Jose A Tierno

Wenbo Liu

Wing Liu

Sumeet Gupta

Wenyi Jin

Sunil Bhosekar

Jaeduk Han

Gary A Rogan

Ming-Shuan Chen

Dhaval H Shah

Yu Cheng Chen

Yu Chen

A receiver circuit including mechanisms for analog channel equalization and channel adaptation is disclosed. The receiver includes a front-end circuit configured to generate a filtered signal by performing filtering of an incoming signal that includes a stream of data symbols. A sample recovery circuit configured to sample an equalized signal, based on the filtered signal, to generate a plurality of recovered data symbols. A decision feedback equalization (DFE) circuit configured to generate the feedback signal based on the plurality of recovered data symbols. A logic circuit is configured to cause adjustment to one or more filters in the front-end circuit based on the plurality of recovered data symbols.

Analog channel equalization and channel adaptation

A serial data receiver subsystem of a computer system includes a data rate detection circuit and a receiver circuit. The data rate detection circuit is configured to detect that a communication link operates in a high-speed mode rather than in a low-speed mode by detecting that a number of transitions in a serial data stream over a reference period of time exceeds a threshold value. The date rate detection circuit is further configured to activate a data rate detection signal indicating that the communication link operates in the high-speed mode, the data rate detection signal activated in response to detection that the number of transitions in the serial data stream over the reference period of time exceeds the threshold value. The receiver circuit is configured to activate one or more of a plurality of subcircuits included in the receiver circuit in response to activation of the data rate detection signal.

Data detection on serial communication links

A serial data receiver subsystem included in a computer system may include a data detection circuit, a speed detection circuit, and a receiver circuit that includes multiple subcircuits. The data detection circuit performs a comparison of a reference voltage to the magnitude of signals received via a communication link that encodes a serial data stream consisting of multiple data symbols. Using a result of the comparison, the data detection circuit may activate a signal present indicator indicating the presence of data on the communication link. Once the signal present indicator is active, the speed detection circuit checks the number of transitions to determine a rate at which data is being transmitted. In response to a determination that the rate of the data being transmitted exceeds a threshold value, the receiver circuit activates one or more of the multiple subcircuits.

An apparatus includes a receiver buffer, a phase compensation circuit, a data sampler circuit, and an error sampler circuit. The receiver buffer may generate an equalized signal on a signal node using an input signal received via a channel. The phase compensation circuit may, in response to an initiation of a training mode, replace the equalized signal on the signal node with a reference signal. The data sampler circuit may sample, using a data clock signal, the reference signal to generate a plurality of data samples. The error sampler circuit may sample, using an error clock signal, the reference signal to generate a plurality of errors samples. The phase compensation circuit may also adjust a phase difference between the data clock signal and the error clock signal using at least some of the plurality of data samples and at least some of the plurality of error samples.

Serial data receiver with sampling clock skew compensation

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Fremont, CA, United States of America

Vishal Varma