摘要:
In described embodiments, a receiver includes a clock and data recovery (CDR) circuit with a voltage control oscillator (VCO) having proportional and integral loop control, and a Lock to Reference (L2R) mode circuit using Phase and Frequency Detector (PFD) control of the VCO during the absence of input data to the CDR. A regular CDR second order loop incorporating PFD control of the VCO during the absence of input data to the CDR achieves relatively rapid lock to reference when compared to counter-based lock to reference mode of operation.
摘要:
In described embodiments, a receiver includes a clock and data recovery (CDR) circuit with a voltage control oscillator (VCO) having proportional and integral loop control, and a Lock to Reference (L2R) mode circuit using Phase and Frequency Detector (PFD) control of the VCO during the absence of input data to the CDR. A regular CDR second order loop incorporating PFD control of the VCO during the absence of input data to the CDR achieves relatively rapid lock to reference when compared to counter-based lock to reference mode of operation.
摘要:
Methods and apparatus are provided for adaptation of continuous time-decision feedback equalizers with programmable adaptation patterns. A continuous time-decision feedback equalizer is adapted by obtaining at least one programmable signature pattern that triggers adaptation of one or more of a pole and a gain of the continuous time-decision feedback equalizer; detecting the at least one programmable signature pattern in an incoming signal; and adapting one or more of the pole and the gain of the continuous time-decision feedback equalizer when the at least one programmable signature pattern is detected in the incoming signal. The programmable signature pattern can be selected to ensure an unambiguous direction of change in an error sample when a corresponding one of the pole and the gain are modified.
摘要:
Methods and apparatus are provided for adaptation of continuous time-decision feedback equalizers with programmable adaptation patterns. A continuous time-decision feedback equalizer is adapted by obtaining at least one programmable signature pattern that triggers adaptation of one or more of a pole and a gain of the continuous time-decision feedback equalizer; detecting the at least one programmable signature pattern in an incoming signal; and adapting one or more of the pole and the gain of the continuous time-decision feedback equalizer when the at least one programmable signature pattern is detected in the incoming signal. The programmable signature pattern can be selected to ensure an unambiguous direction of change in an error sample when a corresponding one of the pole and the gain are modified.
摘要:
In described embodiments, a clock alignment system with a digital bang-bang phase detector (BBPD) employs digitally implemented hysteresis. A first BBPD is employed for a phase control loop that compares the phases from two different clock domain sources, where one clock domain source is used as a reference clock for the phase control loop. A second BBPD with delayed reference clock is employed to resolve ambiguous phase relations seen by the first BBPD. An initial state of a BBPD vector, defined as a vector of current values of the first BBPD and the second BBPD, is examined. Based on the initial and subsequent states of the BBPD vector, the non-reference clock is permitted to naturally move to a lock state through action of the phase control loop, or forced to have its phase rotate clockwise or counterclockwise to reach the lock state.
摘要:
A voltage controlled delay loop and method are disclosed for clock and data recovery applications. The voltage controlled delay loop generates clock signals having similar frequency and different phases. The voltage controlled delay loop comprises a plurality of delay elements; and an input that selectively injects a reference clock into any one of the plurality of delay elements. The plurality of delay elements are connected in series, such as in a loop. In one exemplary implementation, each delay element has an associated multiplexer that selects one of the reference clock and a signal from a previous delay element.
摘要:
A compensation circuit for reducing power consumption in at least one digital circuit includes a first sample circuit connected to a first supply voltage, a second sample circuit connected to a second supply voltage, and a controller connected to the first and second sample circuits. The first and second sample circuits are substantially functionally equivalent to one another but optimized for different regions of operation within a specified range of PVT conditions. The controller is operative to receive respective output signals from the first and second sample circuits, to monitor a functionality of the second sample circuit relative to the first sample circuit, and to adjust a level of the second supply voltage to ensure correct operation of the second sample circuit throughout the specified range of PVT conditions. The digital circuit is operative from the second supply voltage.
摘要:
The various embodiments of the invention provide an apparatus, system and method of asynchronous testing a serializer and deserializer data communication apparatus (SERDES) for determining frequency and phase locking to pseudo asynchronous input data having a continual phase offset. An exemplary apparatus includes a data sampler adapted to sample input serial data and to provide output data; a controlled tap delay with a selected tap having a phase offset from the input serial data, in which the selected tap is selectively coupleable to the data sampler to provide pseudo asynchronous input serial data; a first variable delay control adapted to delay a reference frequency provided to the controlled tap delay in response to the pseudo asynchronous input serial data; and a second delay control adapted to adjust the plurality of taps in response to the pseudo asynchronous input serial data. In additional embodiments, the pseudo asynchronous input serial data is provided from an interpolated phase from at least two selected taps.
摘要:
Methods and apparatus are provided for determining the threshold position of one or more latches employed for decision-feedback equalization. A threshold position of a latch employed by a decision-feedback equalizer is determined by constraining input data such that the input data only contains transitions from a first binary value; obtaining a plurality of samples of a single-sided data eye associated with the constrained input data; and determining a threshold position of the latch based on the samples. The constrained input data can comprise (i) transitions from a binary value of 1 to a binary value of 0 or 1; or (ii) transitions from a binary value of 0 to a binary value of 0 or 1. The size of the single-sided data eye can be obtained by analyzing a histogram associated with the single-sided data eye to identify a region having a constant hit count.
摘要:
Methods and apparatus are provided for serializer/deserializer transmitter synchronization. A plurality of channels are synchronized in one or more serializer/deserializer devices by generating a synchronization request in one or more of the channels; generating an enable signal in response to the synchronization request; and generating a gated synchronization signal for only one or more periods of a synchronization signal in response to the enable signal. The gated synchronization signal can optionally be deasserted after the one or more periods of a synchronization signal.