Cavium, Inc.

Omer O Yildirim

Scott E Meninger

David Lin

JingDong Deng

A method and apparatus select an optimal frequency band of a plurality of frequency bands of a multi-band voltage-controlled oscillator (VCO) to achieve a particular output frequency from the multi-band VCO. The optimal frequency band is selected, automatically, based on performing a one-point calibration phase followed by a multi-point calibration phase. The one-point calibration phase produces an initial frequency band selection and the multi-point calibration phase selects the optimal frequency band from a group of frequency bands including the initial frequency band selection, a higher frequency band consecutively higher in frequency relative to the initial frequency band selection, and a lower frequency band consecutively lower in frequency relative to the initial frequency band selection.

Method and apparatus for multi-band voltage-controlled oscillator (VCO) band selection

A frequency divider circuit comprises a first divider chain including at least one first divider cell and a second divider chain coupled to the first divider chain to form an extendable divider chain. The second divider chain includes at least one second divider cell with a respective reset control. An effective length of the extendable divider chain may be altered, dynamically, via the respective reset control. Altering the effective length, dynamically, enables a division ratio of the frequency divider circuit to be changed, dynamically. The frequency divider circuit may be advantageously employed by applications that rely upon a dynamic division ratio, such as a fractional-N (frac-N) phase-locked loop (PLL).

Frequency divider

In an embodiment, a voltage-controlled oscillator circuit includes a gain element and an LC resonator coupled with the gain element, the LC resonator including an inductor section and a capacitor section. The capacitor section has at least two branches connected in parallel and a voltage control input for tuning the LC resonator. Any of the at least two branches is selected from the group of DC-coupled and AC-coupled. Characteristics of the two branches and bias voltages of the AC-coupled branches are selected to provide a tuning curve of the voltage-controlled oscillator circuit that is approximately linear.

Voltage-controlled oscillator with improved tuning curve linearization

According to at least one example embodiment, a method and corresponding system, or circuit, for calibrating a reference voltage of a single-ended receiver, include applying a clock signal and a reference voltage signal as inputs to the differential amplifier of the single-ended receiver. The differential amplifier provides an output signal, the output signal is processed, and an indication of a duty cycle associated with an output signal of the amplifier is evaluated. Based on the evaluated indication of the duty cycle, a control logic module, or circuit, adjusts a level of the reference voltage signal. The process of evaluating the indication of the duty cycle and adjusting the reference voltage level is repeated for a number of iterations.

Method and apparatus for reference voltage calibration in a single-ended receiver

According to at least one example embodiment a two phase calibration approach is employed for calibrating an input/output interface having multiple single-ended receivers. During a first phase, amplifier offset calibration is applied to each of the multiple single-ended receivers. During a second phase, reference voltage calibration is applied to a single-ended receiver of the multiple single-ended receivers to determine a calibration reference voltage value. The calibration reference voltage value is then employed in each of the multiple single-ended receivers during an active phase of the input/output interface.

Method and apparatus for calibrating an input interface

According to at least one example embodiment, a method and corresponding system for calibrating an amplifier offset include applying an input value to both input leads of an amplifier. The amplifier includes one or more digital-to-analog converters (DACs) used to calibrate an offset of the amplifier. A digital value, provided as input to the DAC, is updated over a number of iterations, by a control logic coupled to the amplifier, based on an output of the amplifier. A final value of the digital value being updated, e.g., associated with the last iteration, is employed as input to the DAC of the one or more DACs in the amplifier for calibrating the offset of the amplifier during a data reception phase.

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Marlborough, MA, United States of America

Omer O Yildirim