Apple Inc.

Wenbo Liu

Sanjeev K Maheshwari

Ming-Shuan Chen

Lizhi Zhong

Raman S Thiara

Wing Liu

Vishal Varma

Sunil Bhosekar

Jaeduk Han

Gary A Rogan

Gokce Gurun

Shingo Hatanaka

Ajay M Rao

Wei-Ming Lee

A phase detector circuit for use with a multi-level signaling communication protocol on a serial communication link is disclosed. The phase detector circuit employs multiple phase and logic circuits to detect data state changes between adjacent ones of voltage levels corresponding to different data states in the communication protocol, and generates early/late signals using the detected data state changes. The phase detector circuit statistically filters data state transitions between non-adjacent voltage levels to improve phase locking and reduce recovered clock jitter.

Phase detector circuit for multi-level signaling

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

A voltage regulator circuit included in a computer system may include a switch device coupled between an input power supply node and a regulated power supply node. The switch device may change a value of a supply current flowing from the input power supply node and the regulated power supply node to regulate a voltage level of the regulated power supply node. A noise cancelation current may be feed forward onto a control terminal of the switch device to cancel noise on the regulated power supply node resulting from noise present on the input power supply node.

Low dropout regulator with feedforward power supply noise rejection circuit

A multi-stage clock generation circuit is disclosed. The circuit includes first and second ring oscillators. The ring oscillators include a corresponding plurality of delay elements coupled in series, with a plurality of shunt circuits in parallel with corresponding inverters. The shunt circuits include respective interpolation nodes, which are resistively coupled to input and output nodes of their corresponding inverters. The interpolation nodes of the first ring oscillator are coupled to delay element input and output nodes of the second ring oscillator. Similarly, the interpolation nodes of the second ring oscillator are coupled to delay element input and output nodes of the first ring oscillator.

Multi-stage clock generator using mutual injection for multi-phase generation

Techniques are disclosed relating to clock and data recovery circuitry. In some embodiments, a slicing circuit may be configured to sample an input signal to generate a first and second sampled data signal. In some embodiments, a phase detector circuit may be configured to compare the phases of the first and second sampled data signals. In some embodiments, a first charge pump may be configured to supply a first current to a circuit node, and a second charge pump may be configured to supply a second current to the circuit node. In some embodiments, a voltage-controlled oscillator may be configured to adjust a frequency of first and second clock signals based on a voltage of the circuit node.

Jitter reduction in clock and data recovery circuits

A wired-line transmitter may include architecture that provides control of the current profile during power-up and/or power-down of the transmitter. The current profile may include a sloped ramp up during power-up and/or a sloped ramp down during power-down. The sloped ramps of the current profile mitigate supply bouncing during power-up and/or power-down. Individual enable signals may be derived from an enable signal provided to the transmitter. These individual enable signals may be provided (or turned off) in a time delayed (e.g., staggered) manner to provide the sloped ramps for the current profile.

Mitigation of power supply disturbance for wired-line transmitters

In some embodiments, a digital-to-analog converter (DAC) system includes an output segment, a main branch, first and second edge segments, and a sub-segment. The output segment includes secondary switches that selectively connect conductive paths to an output. The main branch includes unit resistance elements, each including a resistor and a switch. The first and second edge segments each include a respective group of secondary switches that selectively connect a respective conductive path to a unit resistance element. The sub-segment includes terminal resistors connected to at least one conductive path and includes main switches that selectively connect respective terminal resistors to the unit resistance element. The main switches and the unit resistance element switches use a single switch design. The DAC system may have an improved differential non-linearity (DNL), as compared to a DAC system that does not include the unit resistance element switches or the first and second edge segments.

Growing community of inventors

Cupertino, CA, United States of America

Wenbo Liu