Systems, apparatuses, and methods for performing asynchronous memory clock changes on multiple displays are disclosed. From time to time, a memory clock frequency change is desired for a memory subsystem storing frame buffer(s) used to drive pixels to multiple displays. For example, when the real-time memory bandwidth demand differs from the memory bandwidth available with the existing memory clock frequency, a control unit tracks the vertical blanking interval (VBI) timing of a first display. Also, the control unit causes a second display to enter into panel self-refresh (PSR) mode. Once the PSR mode of the second display overlaps with a VBI of the first display, a memory clock frequency change, including memory training, is initiated. After the memory clock frequency change, the displays are driven by the frame buffer(s) in the memory subsystem at an updated frequency.

A semiconductor memory device includes a quadrature error correction circuit, a clock generation circuit and a data input/output (I/O) buffer. The quadrature error correction circuit performs a locking operation to generate a first corrected clock signal and a second corrected clock signal by adjusting a skew and a duty error of a first through fourth clock signals generated based on a data clock signal and performs a relocking operation to lock the second corrected clock signal to the first corrected clock signal in response to a relock signal. The clock generation circuit generates an output clock signal and a strobe signal based on the first corrected clock signal and the second corrected clock signal. The data I/O buffer generates a data signal by sampling data from a memory cell array based on the output clock signal and transmits the data signal and the strobe signal to a memory controller.

Methods of operating a memory device are disclosed. A method may include asserting, at a semiconductor device, an internal signal in response to receipt of a command. The method may also include holding the internal signal in an asserted state for at least a predetermined time duration upon assertion of the internal signal. Further, the method may include generating an enable signal based on the internal signal and a clock signal. Associated devices and systems are also disclosed.

Methods, systems, and devices for detection of illegal commands are described. A memory device, such as a dynamic random access memory (DRAM), may receive a command from a device, such as a host device, to perform an access operation on at least one memory cell of a memory device. The memory device may determine, using a detection component, that a timing threshold associated with an operation of the memory device would be violated by performing the access operation. The memory device may refrain from executing the access operation based on determining that performing the access operation included in the command would violate the timing threshold. The memory device may transmit, to the device, an indication that performing the command would violate the timing threshold.

An apparatus includes a host and a memory device connected to the host through a bus. The bus is used to communicate a data clock controlling data write timing during a write operation executed by the memory device and a read clock controlling data read timing during a read operation executed by the memory device. The memory device performs first duty cycle monitoring that monitors a duty cycle of the data clock, generates a first result, and provides a timing-adjusted data clock, performs second duty cycle monitoring that monitors a duty cycle of the read clock, generates a second result, and provides a timing-adjusted read clock, calculates an offset of the read clock based on the timing-adjusted data clock, the result and the second result, and corrects a duty error of the read clock using a read clock offset code derived from the offset of the read clock.

Technology is disclosed herein for semi receiver side write training in a non-volatile memory system. The transmitting device has delay taps that control the delay between a data strobe signal and data signals sent on the communication bus. The delay taps on the transmitting device are more precise that can typically be fabricated on the receiving device (e.g., NAND memory die). However, the receiving device performs the comparisons between test data and expected data, which alleviates the need to read back the test data. After the different delays have been tested, the receiving device informs the transmitting device of the shortest and longest delays for which data was validly received. The transmitting device then sets the delay taps based on this information. Moreover, the write training can be performed in parallel on many receiving devices, which is very efficient.

A memory device according to the present invention may comprise: a memory cell array in which memory cells are connected in matrix form to word lines and bit lines; a plurality of mergers connected in series to transfer data that is read from a selected memory cell among the memory cells included in the memory cell array and is transformed into one of a direct current form or a pulse form; and a sorter that synchronizes an edge of first output data, output by one of the plurality of mergers, with an edge of a control pulse, thereby delaying the edge of the first output data. First data, which is either data bit “0” or data bit “1”, can be input to the mergers in the form of a direct current of first logic, and second data, which is another piece of data, can be input to the mergers in the form of a pulse that changes from the first logic to the second logic and back to the first logic. When the first data is input, the sorter can allow the first data to pass as-is and output the first data as second output data in the form of a direct current of the first logic. When a first edge that changes from the second logic to the first logic is input, the sorter can delay the first edge by synchronizing the same with a rising edge or falling edge of the control pulse, and output the first edge as the second output data.

In an embodiment, a system includes an energy source and an integrated circuit that is coupled to one or more memory devices via a plurality of memory channels. A memory controller in the integrated circuit is programmable with a plurality of identifiers corresponding to the plurality of channels, and is further programmable with a command and a first identifier associated with the command. Responsive to the command, the memory controller is configured to perform one or more calibrations on a subset of the plurality of channels for which corresponding identifiers of the plurality of identifiers match the first identifier. Other ones of the plurality of channels, for which the corresponding identifiers do not match the first identifier, do not perform the calibration.

A memory controller includes a first receiver configured to compare a read reference voltage with a piece of data received through a first data line and output a first piece of data; a first duty adjuster configured to adjust a duty of the first piece of data; a second receiver configured to compare the read reference voltage with a piece of data received through a second data line and output a second piece of data; a second duty adjuster configured to adjust a duty of the second piece of data; and a training circuit configured to perform a training operation on pieces of data received through a plurality of data lines, to obtain a target read reference voltage for each piece of data and correct a duty of each piece of data based on a level of the target read reference voltage for each piece of data.

A method of operating a memory device includes receiving a duty training request, performing first training for a write path in a first period, storing a result value of the first training, performing second training for a write path in a second period, storing a result value of the second training, transmitting the result value of the first training to an external device, and receiving a duty cycle adjuster (DCA) code value corresponding to the first training result value from the external device.