摘要:
An on-die scope is described. The on-die scope can include one or more scope slicers, phase sweeping circuitry, voltage sweeping circuitry, and eye-diagram data collection circuitry. The clock and data recovery circuitry can receive an input signal, and output a recovered clock signal and a recovered bit-stream. The phase sweeping circuitry can receive the recovered clock signal, and output the scope clock signal by adding a phase offset to the recovered clock signal. A scope slicer can receive the voltage threshold, the scope clock signal, and the input signal, and output a scope bit-stream. The eye-diagram data collection circuitry can detect one or more bit-patterns in the recovered bit-stream, and modify values of one or more scope counters based solely or partly on the scope bit-stream and the recovered bit-stream.
摘要:
Systems and techniques for adapting and/or optimizing an equalizer of a receiver are described. The equalizer's behavior can be adjusted by modifying one or more equalization parameters. At the beginning of the adaptation and/or optimization process, the system can determine robust initial values for the one or more equalization parameters. The system can then adapt and/or optimize the equalizer by iteratively adjusting the one or more equalization parameters. Specifically, in each iteration, the system can use the receiver's clock and data recovery (CDR) circuitry to determine the number of early and late data transitions associated with one or more data patterns. Next, the system can adjust the one or more equalization parameters so that, for each data pattern in the one or more data patterns, the ratio between the number of early data transitions and the number of late data transitions is substantially equal to a desired value.
摘要:
Systems and techniques for adapting and/or optimizing an equalizer of a receiver are described. The equalizer's behavior can be adjusted by modifying one or more equalization parameters. At the beginning of the adaptation and/or optimization process, the system can determine robust initial values for the one or more equalization parameters. The system can then adapt and/or optimize the equalizer by iteratively adjusting the one or more equalization parameters. Specifically, in each iteration, the system can use the receiver's clock and data recovery (CDR) circuitry to determine the number of early and late data transitions associated with one or more data patterns. Next, the system can adjust the one or more equalization parameters so that, for each data pattern in the one or more data patterns, the ratio between the number of early data transitions and the number of late data transitions is substantially equal to a desired value.
摘要:
An on-die scope is described. The on-die scope can include one or more scope slicers, phase sweeping circuitry, voltage sweeping circuitry, and eye-diagram data collection circuitry. The clock and data recovery circuitry can receive an input signal, and output a recovered clock signal and a recovered bit-stream. The phase sweeping circuitry can receive the recovered clock signal, and output the scope clock signal by adding a phase offset to the recovered clock signal. A scope slicer can receive the voltage threshold, the scope clock signal, and the input signal, and output a scope bit-stream. The eye-diagram data collection circuitry can detect one or more bit-patterns in the recovered bit-stream, and modify values of one or more scope counters based solely or partly on the scope bit-stream and the recovered bit-stream.
摘要:
Some embodiments of the present invention provide a voltage-mode transmitter. The transmitter can include configuration circuitry, bias circuitry, and a set of driver slices. Each driver slice can include driver transistors which drive an output value. The outputs of each driver slice can be directly or capacitively coupled with the transmitter's outputs. Each driver slice can also include one or more impedance-matching transistors which are serially coupled to at least some of the driver transistors. The configuration circuitry can configure a subset of driver slices so that the down (or up) impedance of the transmitter is within a first tolerance of a desired impedance value. The bias circuitry can bias the one or more impedance-matching transistors in each driver slice in the subset of driver slices so that the up (or down) impedance is within a second tolerance of the down (or up) impedance.
摘要:
One embodiment of the present invention provides a phase-locked loop (PLL) for synthesizing a fractional frequency. The PLL can include a 1/N frequency divider, a voltage-controlled oscillator (VCO), a programmable phase mixer, and a phase detector. The programmable phase mixer can be coupled between an output of the VCO and an input of the frequency divider, wherein the programmable phase mixer is configured to receive the output clock signal from the VCO and generate a first clock signal of frequency f1 by varying a phase of the output clock signal. The frequency divider is configured to receive the first clock signal from the programmable phase mixer and generate a second clock signal of frequency f2=f1/N. The phase detector can receive a reference clock signal and the second clock signal as inputs, and the phase detector's output can be used to generate the control voltage for the VCO.
摘要:
One embodiment of the present invention provides a phase-locked loop (PLL) for synthesizing a fractional frequency. The PLL can include a 1/N frequency divider, a voltage-controlled oscillator (VCO), a programmable phase mixer, and a phase detector. The programmable phase mixer can be coupled between an output of the VCO and an input of the frequency divider, wherein the programmable phase mixer is configured to receive the output clock signal from the VCO and generate a first clock signal of frequency f1 by varying a phase of the output clock signal. The frequency divider is configured to receive the first clock signal from the programmable phase mixer and generate a second clock signal of frequency f2=f1/N. The phase detector can receive a reference clock signal and the second clock signal as inputs, and the phase detector's output can be used to generate the control voltage for the VCO.
摘要:
An integrated circuit that includes a receive data path is described. The receive data path: equalizes a received analog signal, converts the resulting equalized analog signal to digital data values based on a clock signal, and recovers the clock signal in the digital data values. The integrated circuit also includes an on-chip oscilloscope. The oscilloscope includes: two comparators, a phase rotator that outputs an oscilloscope clock signal whose phase can be varied relative to that of the recovered clock signal, and an offset circuit that outputs a voltage offset. Based on the voltage offset and the oscilloscope clock signal, the comparators output digital values which can be used to determine eye patterns that correspond to the analog signal before and after equalization. The eye patterns can then be correlated with an error rate associated with the received data.
摘要:
Circuitry to facilitate testing of serial interfaces is described. Specifically, some embodiments of the present invention facilitate testing the clock and data recovery functionality of a receiver. A serial interface can include a multiplying phase locked loop (MPLL) clock generator, a transmitter, and a receiver. The MPLL clock generator can generate a first clock signal and a second clock signal, and can vary a phase and/or frequency difference between the first clock signal and the second clock signal. During test, the transmitter and the receiver can be directly or capacitively coupled to each another. Specifically, during test, the serial interface can be configured so that the transmitter transmits data using the first clock signal, and the receiver receives data using the second clock signal. The clock and data recovery functionality of the receiver can be tested by comparing the transmitted data with the received data.
摘要:
Some embodiments of the present invention provide a voltage-mode transmitter. The transmitter can include configuration circuitry, bias circuitry, and a set of driver slices. Each driver slice can include driver transistors which drive an output value. The outputs of each driver slice can be directly or capacitively coupled with the transmitter's outputs. Each driver slice can also include one or more impedance-matching transistors which are serially coupled to at least some of the driver transistors. The configuration circuitry can configure a subset of driver slices so that the down (or up) impedance of the transmitter is within a first tolerance of a desired impedance value. The bias circuitry can bias the one or more impedance-matching transistors in each driver slice in the subset of driver slices so that the up (or down) impedance is within a second tolerance of the down (or up) impedance.