A multi-channel receiver that includes a first clock recovery unit configured to recover a first clock signal associated with a first optical channel is disclosed. A first coefficient estimation unit estimates a first set of coefficients using the first clock signal. A second clock recovery unit configured to recover a second clock signal associated with a second optical channel using the first clock signal as a reference clock signal. A second coefficient estimation unit estimates a second set of coefficients using the first set of coefficients.

An apparatus is provided which comprises: a data slicer to receive first data sampled by a data clock; an edge slicer to receive second data sampled by an edge clock; and a Least Mean Square (LMS) circuitry coupled to the data and edge slicers, wherein the LSM circuitry is to generate a code to adjust a phase of one of data clock and/or edge clock relative to one another.

Phase detectors for clock and data recovery circuits are provided herein. In certain implementations, a phase detector includes sampling circuitry that generates a plurality of samples of an input data signal based on timing of a plurality of clock signals, a binary response circuit that processes the plurality of samples to generate a plurality of binary output signals providing a binary detector response, and a linear response circuit that processes the plurality of samples to generate a plurality of linear output signals providing a linear detector response. The phase detector generates one or more data output signals based on the plurality of samples to thereby recover data from the input data signal.

A method and system implements a repeater in a link of a communication medium. The method and system enables a counter to count alternations of a clock signal received from a host or device over the link, compares a value of the counter to a reference count, adjusts a frequency selection based on the comparison of the value of the counter to the reference count, and locks the frequency selection in response to the counter matching the reference count.

Apparatus and methods are provide for a multichannel clock and data recovery (CDR) device that shares information between channels. In an example, a multiple channel communication circuit can include a plurality of clock and data recovery (CDR) circuits, each CDR circuit of the plurality of CDR circuits associated with a channel of the multiple channel communication circuit. In certain examples, each CDR circuit can be configured to detect an incoming stream of data from the channel, to determine a setting of one or more parameters for correctly sampling the data from the incoming stream, and to share an indication of the setting of the one or more parameters to an adjacent CDR circuit of the plurality of CDR circuits.

A signal recovery circuit includes an oscillator configured to control a frequency of generating first clock, and a feedback circuit configured to control the oscillator in order that input data is synchronized with the first clock in accordance with a phase relation between the input data and the first clock, wherein the feedback circuit includes a controller configured to control the oscillator in accordance with the phase relation between the input data and the first clock, a first phase detector configured to generate a clock phase control signal in accordance with the phase relation between the input data and the first clock, and a state detection circuit configured to detect whether the signal recovery circuit is in a locked state or an unlocked state, based on a magnitude of an amplitude of a first component or a second component of the clock phase control signal.

A method, system and apparatus, for bootstrapping an autonegotiation signal in an intermediate device. The intermediate device initializes using a referenceless clock circuit. The intermediate device then recovers a more accurate clock sourced from a second device via a clock data recovery circuit in the intermediate device. The second device has a physical medium attachment interface within the intermediate device that does not require autonegotiation. The autonegotiation signal is communicated to a first device having a physical medium dependent interface to the intermediate device, thus requiring autonegotiation.

A Continuous Time Linear Equalizer (CTLE) and a method of operating a CTLE in a receiver for a Pulse Amplitude Modulation (PAM) signal are disclosed. The method includes initiating equalization using an initial equalization setting that is optimized to meet a first objective and responsive to a determination, shifting to a final equalization setting that is optimized to meet a second objective.

A CDR circuit includes: a comparison circuit that receives data signal on which a first clock signal is superimposed, and outputs a comparison result obtained by comparing the data signal with three different threshold values at a timing synchronized with a second clock signal; a data pattern detection circuit that detects an occurrence of a data pattern, based on the comparison result; a frequency detection circuit that outputs, when an occurrence of the data pattern is detected, a detection result indicating whether a second frequency of the second clock signal is higher than a first frequency of the first clock signal; an adjustment circuit that outputs, based on the detection result, an adjustment signal for adjusting a phase of the second clock signal and the second frequency; and an oscillator circuit that outputs the second clock signal with the phase and the second frequency adjusted, based on the adjustment signal.

A clock data recovery (CDR) circuit includes: a band select circuit, a low dropout regulator (LDO), a charge pump and a voltage-controlled oscillator (VCO), wherein the band select circuit is arranged to generate a digital signal according to at least a reference voltage; the LDO is arranged to regulate a ground voltage, wherein the LDO adjusts an operating band of the LDO by receiving at least a part of the digital signal to adjust a bias current of an amplifier of the LDO; the charge pump is arranged to generate a control voltage according to at least a part of the digital signal; and the VCO is arranged to generate a clock signal according to the control voltage, wherein the VCO adjusts an operating band of the CDR circuit by receiving at least a part of the digital signal to adjust a bias current of the VCO.