Nvidia Corporation

Vipul Katyal

Virendra Kumar

Ish Chadha

Abhijith Kashyap

Hao-Yi Wei

Bobak Modaress-Razavi

Techniques for improving the accuracy of delay line calibration schemes. For example, an amount of offset may be determined between one or more first portions of a first clock signal and one or more second portions of a second clock signal that is delayed relative to the first clock signal. The first portion(s) may correspond to the second portion(s) based at least on the second clock signal being delayed relative to the first clock signal. In some examples, a value may be determined based at least on the amount of offset. The value may correspond to an amount to adjust the first clock signal to reduce the amount of offset. In some examples, a delay line may then be calibrated, based at least on the second value, to adjust the first clock signal.

Delay line calibration based on derived reference signals

Embodiments include a memory device with an improved circuit to mitigate degradation of memory devices due to aging. Memory device input/output pins include delay elements for adjusting the delay in each memory input/output signal path to synchronize the input/output signal paths with one another. Certain data patterns, including a long series of logic zero values or a long series of logic one values, can cause asymmetric degradation of transistors included in the delay elements. This asymmetric degradation can reduce the operating frequency of the memory device, leading to lower performance. The disclosed embodiments change the polarity of signals passing through the delay elements to mitigate the effects of asymmetric degradation resulting from these data patterns. As a result, the performance of memory devices is improved relative to prior approaches.

Mitigating duty cycle distortion degradation due to device aging on high-bandwidth memory interface

Embodiments include a memory device with an improved calibration circuit. Memory device input/output pins include delay lines for adjusting the delay in each memory input/output signal path. The delay adjustment circuitry includes digital delay lines for adjusting this delay. Further, each digital delay line is calibrated via a digital delay line locked loop which enables adjustment of the delay through the digital delay line in fractions of a unit interval across variations due to differences in manufacturing process, operating voltage, and operating temperature. The disclosed techniques calibrate the digital delay lines by measuring both the high phase and the low phase of the clock signal. As a result, the disclosed techniques compensate for duty cycle distortion by combining the calibration results from both phases of the clock signal. The disclosed techniques thereby result in lower calibration error relative to approaches that measure only one phase of the clock signal.

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San Jose, CA, United States of America

Vipul Katyal