135 results about "CAS latency" patented technology

An apparatus and method to delay output of data from different regions of a memory device in response to a read enable signal, the delaying of the output of data is based on the location of the regions of the memory device with respect to an output circuit that receives the data, wherein the different regions of the memory device have different CAS latency values dedicated to each region to set the delay time of each region of the memory device.

Systems and methods are described for resolving certain interoperability issues among multiple types of memory modules in the same memory subsystem. The system provides a single data load DIMM for constructing a high density and high speed memory subsystem that supports the standard JEDEC RDIMM interface while presenting a single load to the memory controller. At least one memory module includes one or more DRAM, a bi-directional data buffer and an interface bridge with a conflict resolution block. The interface bridge translates the CAS latency (CL) programming value that a memory controller sends to program the DRAMs, modifies the latency value, and is used for resolving command conflicts between the DRAMs and the memory controller to insure proper operation of the memory subsystem.

A method of selecting CAS latencies in a system. Specifically, a system which includes a plurality of memory devices and a memory controller is provided. Because different memory devices may have different CAS latencies, a system CAS latency is selected wherein the system CAS latency is the fastest common CAS latency of each of the plurality of memory devices. After a read request is delivered to a memory device, the memory controller initiates a transmission flag to the memory device at a time equal to the system CAS latency, indicating that it is safe to transmit the requested data from the memory device to the memory controller. The transmission flags may be used in conjunction with mode registers such that one or both of the transmission flag and the data may be received by or delivered by a corresponding memory device.

A data output control circuit controls a data output in a read operation. A data output control method includes a count shifting mode and a delay mode and can be used in low and high frequency operations, so that a data output can be stably controlled in a broad frequency range. The data output control circuit includes: a low frequency mode controller a high frequency mode controller and a selector selecting any one of first and second command signals through CAS latency information to be output as a data output control signal.

An apparatus, for use in a semiconductor device, for providing a domain crossing operation. The apparatus includes a domain crossing sensing block, in response to an operation mode signal, first and second delay locked loop (DLL) clock signals and a CAS latency, generates a plurality of selection signals. An output enable signal generator, in response to the plurality of selection signals, generates a plurality of output enable signals. A data control block, in response to the output enable signals and the CAS latency, controls a data output operation in the semiconductor device. Each of a plurality of data align block, in response to the selection signals, the first and second DLL clock signals and an address signal, aligns data corresponding to the address signal in the data output operation.

A semiconductor memory device is capable of controlling the data output timing depending on the operating frequency so as to output data with optimized for the operating frequency. Further, in the high frequency operation, the memory device can output data reliably so as to facilitate development of high frequency memory device. The semiconductor memory device comprises a frequency sensing unit for sensing an operating frequency by sensing an amount of lead of a delay locked clock in a delay locked loop compared to an external clock signal, an output enable controlling unit for outputting an output enable signal in response to a CAS latency with controlling the output timing of the output enable signal based on the frequency that is sensed by the frequency sensing unit, and a data output buffer for outputting data that is transferred from a memory core region in response to the output enable signal.

A delay line receives an input clock signal and includes a cascaded plurality of unit delay circuits. A mode register set stores a value indicative of a column-address-strobe (CAS) latency of the memory device, and an adjustment circuit varies a delay time of the unit delay circuits according to the CAS latency stored in the mode register set. A phase detector detects a phase difference between the input clock signal and an output clock signal of the delay line, and a control circuit which controls an enabled state of the unit delay circuits according to an output of said phase detector.

A semiconductor memory includes a control circuit for generating an internal read command signal depending on an externally applied read command signal. A clock generating circuit generates a system clock signal and a time shifted clock signal generated by a DLL circuit. A latency counter circuit comprises a first control circuit for generating a first control signal and a second control circuit for generating a second control signal. The first control signal is used to latch the internal read command signal in one of FIFO-latching cells. The latching is carried out in a system clock domain. The second control signal is used to release a time shifted internal read command signal from one of the FIFO-latching cells in a DLL clock domain. The relationship between first and second control signals determines a CAS latency by which data items appear at a data terminal synchronous with an externally applied clock signal.

An output driver effectively controls the slew rate of an output signal according to CAS latency information including frequency information of an operating clock signal or according to frequency information obtained by detecting the frequency of the operating clock signal. The output driver includes an output terminal, a pull-up driver which pulls-up the output terminal, and a pull-down driver which pulls-down the output terminal. Also, the output driver further includes a mode register set (MRS) which stores CAS latency information of the semiconductor memory device. Driving capabilities of the pull-up driver and the pull-down driver are varied in response to the CAS latency information. The output driver may include a frequency detector which detects and stores the operating frequency of the semiconductor memory device. In this case, the driving capabilities of the pull-up driver and the pull-down driver are varied in response to output signals output from the frequency detector.

A data strobe signal generator according to the present invention includes a control unit, a pulse delay unit, a clock generator, and a data strobe output unit. The control unit generates a CAS latency signal and a preamble signal. The pulse delay unit delays a pulse signal for predetermined time and outputs a delayed pulse signal. The clock generator outputs a control clock signal. The data strobe output unit outputs a data strobe signal. The data strobe signal generator and the semiconductor memory device having the same according to the present invention generate a data strobe signal based on an adjustable preamble value, thereby ensuring the stabilized data output operation of a high-speed memory device.

To provide a semiconductor memory device that can ensure adequate read margin by effectively utilizing a period for assigned CAS latency. CAS latency is preset before reading. An ACT command is input to activate a word line corresponding to a row address. A READ command is input at a zeroth clock pulse of an internal clock and a digit line corresponding to a column address is connected to a sense amplifier. A sense amplifier activation signal is activated independently of CAS latency to start an equalizing and sense operation. Afterwards, a sense amplifier activation signal is deactivated after two through 5 cycles depending on CAS latency, and the equalizing and sense operation are terminated. Subsequently, an output operation for transferring the sensed result from the sense amplifier to an output pin is performed, and first data is available from a fifth through the eighth clock pulse depending on CAS latency.

A memory system, memory device, and method for setting an operating mode of a memory device include a memory cell array; row and column decoders which select a row and a column of the memory cell array, respectively, according to a multi-bit address signal; and a mode control circuit which receives at least one bit from the multi-bit address signal used in the selection of the row or the column, and which sets an operating mode of the memory device according to the at least one bit, wherein the operating mode is one of a burst length mode, a DLL reset mode, a test mode, a CAS latency mode, and a burst type mode.

A semiconductor device includes a latency signal generating circuit for generating a latency signal corresponding CAS latency by measuring a delay amount reflected at a delay locked loop and reflecting the measured delay amount at a read command signal, and a delay locked loop for controlling an internal clock signal applied to the latency signal generating circuit corresponding to the read command and the latency signal. The semiconductor device includes an internal clock signal generating block configured to generate an internal clock signal, a latency generating block configured to generate a latency signal by synchronizing a read command signal with the internal clock signal at a time corresponding to a CAS latency value and a measured delay value, and an input controlling block configured to activate the reference clock signal using an external clock signal in response to the read command signal and the latency signal.

A delay-locked loop (DLL) circuit includes a standby signal generating circuit, a front stage circuit, and a back stage circuit. The standby signal generating circuit generates a first standby signal and a second standby signal in response to an active signal, a crock enable signal, a first column address strobe (CAS) latency signal, and a second CAS latency signal. The front stage circuit compares the phase of an external clock signal and the phase of a feedback signal and delays the external clock signal based on the phase difference between the external clock signal and the feedback signal to generate a first clock signal. The back stage circuit executes interpolation and duty-cycle correction on the first clock signal.