Nvidia Corporation

Gautam Bhatia

Robert Bloemer

Sunil Rao Sudhakaran

Kyutaeg Oh

Lizhi Zhong

Peter C Mills

Vishnu Balan

Various embodiments include a memory device that is capable of performing write training operations. Prior approaches for write training involve storing a long data pattern into the memory followed by reading the long data pattern to determine whether the data was written to memory correctly. Instead, the disclosed memory device stores a first data pattern (e.g., in a FIFO memory within the memory device) or generates the first data pattern (e.g., using PRBS) that is compared with a second data pattern being transmitted to the memory device by an external memory controller. If data patterns match, then the memory device stores a pass status in a register, otherwise a fail status is stored in the register. The memory controller reads the register to determine whether the write training passed or failed.

Techniques for performing write training on a dynamic random-access memory

Various embodiments include a memory device that is capable of transferring both commands and data via a single clock signal input. In order to initialize the memory device to receive commands, a memory controller transmits a synchronization command to the memory device. The synchronization command establishes command start points that identify the beginning clock cycle of a command that is transferred to the memory device over multiple clock cycles. Thereafter, the memory controller transmits subsequent commands to the memory device according to a predetermined command length. The predetermined command length is based on the number of clock cycles needed to transfer each command to the memory device. Adjacent command start points are separated from one another by the predetermined command length. In this manner, the memory device avoids the need for a second lower speed clock signal for transferring commands to the memory device.

Techniques for transferring commands to a dynamic random-access memory

First symbols are generated on a plurality of data channels by applying PAM-N encoding on a first subset of bits of a data burst, the first symbols generated without maximum transitions; second symbols are generated on at least one optionally-activated additional data channel, the second symbols generated by applying the PAM-N encoding on a second subset of bits of the data burst, the second symbols generated without maximum transitions; and third symbols are generated on a channel for communicating error correction bits for the first bits and second bits, the third symbols generated by applying hybrid PAM-N encoding on the error correction bits and a third subset of bits of the data burst, the hybrid PAM-N encoding comprising an interleaving of symbols with N voltage levels and symbols with less than N voltage levels.

Error detection pin encoding scheme to avoid maximum transitions and further improve signal integrity on high speed graphic memory interfaces

Various embodiments include a memory device that recovers from write errors and read errors more quickly relative to prior memory devices. Certain patterns of write data and read data may result on poor signal quality on the memory interface between memory controllers and memory devices. The disclosed memory device, synchronously with the memory controller, scrambles read data before transmitting the data to the memory controller and descrambles received from the memory controller. The scrambling and descrambling results in a different pattern on the memory interface even for the same read data or write data. Therefore, when a write operation or a read operation fails, and the operation is replayed, the pattern transmitted on the memory interface is different when the operation is replayed. As a result, the memory device more easily recovers from data patterns that cause poor signal quality on the memory interface.

Techniques for data scrambling on a memory interface

A transceiver configured to communicate a burst of data bits and meta-data bits for the data bits includes data channels, auxiliary data channels, and at least one error correction channel. The transceiver includes an encoder that applies 11b7s encoding to a first number of the data bits to generate first PAM-3 symbols on some or all of the communication channels, and that applies 3b2s encoding to a second number of the data bits to generate second PAM-3 symbols on at least some of the communication channels.

Hardware-efficient PAM-3 encoder and decoder

Various embodiments include a memory device that is capable of performing memory access operations with reduced power consumption relative to prior approaches. The memory device receives early indication as to whether a forthcoming memory access operation is a read operation or a write operation. The memory device enables various circuits and disables other circuits depending on whether this early indication identifies an upcoming memory access operation as a read operation or a write operation. As a result, circuits that are not needed for an upcoming memory access operation are disabled earlier during the memory access operation relative to prior approaches. Disabling such circuits earlier during the memory access operation reduces power consumption without reducing memory device performance.

Techniques for reducing DRAM power usage in performing read and write operations

Data bits are encoded in one or both of an eleven bit seven pulse amplitude modulated three-level (PAM-3) symbol (11b7s) format and a three bit two symbol (3b2s) format on a plurality of data channels and on an error correction channel. One or more of a cyclic redundancy check (CRC) value, a poison value, and a severity value are encoded as 11b7s and/or 3b2s PAM-3 symbols on the error correction channel.

Various embodiments include a memory device that is capable of performing command address interface training operations, to determine that certain timing conditions are met, with fewer I/O pins relative to prior approaches. Prior approaches for command address interface training involve loading data via a set of input pins, a clock signal, and a clock enable signal that identifies when the input pins should be sampled. Instead, the disclosed memory device generates a data pattern within the memory device that matches the data pattern continuously being transmitted to the memory device by an external memory controller. The memory device compares the generated data pattern with the received data pattern and transmits the result of the comparison on one or more data output pins. The memory controller receives and analyzes the result of the comparison to determine whether the command address interface training passed or failed.

Techniques for performing command address in interface training on a dynamic random-access memory

Various embodiments include a memory device that is capable of performing write training operations, to determine that certain timing conditions are met, without storing data patterns in memory. Prior approaches for write training involve storing a long data pattern into the memory followed by reading the long data pattern to determine whether the data was written to memory correctly. Instead, the disclosed memory device generates a data pattern within the memory device that matches the data pattern being transmitted to the memory device by an external memory controller. If the data pattern generated by the memory device matches the data pattern received from the memory controller, then the memory device stores a pass status in a register. If the data patterns do not match, then the memory device stores a pass status in a register. The memory controller reads the register to determine whether the write training passed or failed.

A method comprises receiving an input signal at an input of a receiver and retrieving a data sample signal and an error sample signal from the input signal. The method also comprises applying an adaptive procedure to generate a feedback code using the data sample signal and the error sample signal for feeding back into a decision feedback equalization (DFE) module. Further, it comprises converting the feedback code into a corresponding voltage value and assigning the corresponding voltage value as a tap weight for the DFE module. Finally, it comprises generating an edge sample signal by applying DFE to the input signal using the DFE module, wherein the DFE is based on the tap weight.

Adaptation of crossing DFE tap weight

One embodiment provides a data-receiving device component comprising a phase shifter, timer logic, and control logic. The phase shifter is configured to release a train of clock pulses with a controlled phase shift. The timer logic is configured to receive data from a data-sending device, and for each transition of the data received, to determine whether a clock pulse from the train is early or late with respect to the transition, and to tally the late clock pulses relative to the early clock pulses. The control logic, operatively coupled to the phase shifter and to the timer logic, is configured to incrementally advance the phase shift when the late clock pulses outnumber the early clock pulses by a non-integer power of two.

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Mountain View, CA, United States of America

Gautam Bhatia