135 results about "CAS latency" patented technology

An output enable signal generation circuit of a semiconductor memory includes: a latency signal generation unit configured to generate a latency signal for designating activation timing of a data output enable signal in response to a read signal and a CAS latency signal; and a data output enable signal generation unit configured to control the activation timing and deactivation timing of the data output enable signal in response to the latency signal and a signal generated by shifting the latency signal based on a burst length (BL).

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 synchronous memory device which generates a data output enable signal corresponding to a set CAS latency mode including: a control clock generator for generating an A-type first control clock and a B-type first control clock; a first redundancy enable signal generator for shifting an internal read signal by a predetermined interval in synchronization with one of the A-type first control clock and the B-type first control clock and generating a plurality of first redundancy enable signals; a second redundancy enable signal generator for synchronizing the plurality of first redundancy enable signals with a DLL clock and generating a plurality of second redundancy enable signals; and an output enable signal generator for selecting one redundancy enable signal corresponding to the set CAS latency mode among the first redundancy enable signals and the second redundancy enable signals and generating the selected redundancy enable signal as the data output enable signal.

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.

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.

Disclosed herein is a semiconductor memory device for reducing an unnecessary current consumption occurred in an idle state or an active state. The semiconductor memory device includes a driving clock supply unit for supplying a driving clock during a read or a write operation of each bank; a delay unit for generating a read address or a write address in synchronization with the driving clock by delaying an address by a predetermined time based on one of an additive latency, a CAS latency and a combination thereof; and an output unit for latching the read address or the write address to output the latched signal as an internal column address.

A data output control circuit for use in a synchronous semiconductor memory device, which has a plurality of CAS latency modes, includes a signal generating unit for generating an internal signal corresponding to an input command; a CAS latency mode control unit for outputting the internal signal as a controlled internal signal; a signal shifting unit for generating a plurality of shifted signals by synchronizing the controlled internal signal with a DLL clock signal; and a data output enable signal generating unit for outputting one of the plurality of shifted signals as a data output enable signal depending on a plurality of control signals, wherein each of the plurality of control signals corresponds to two or more continuous CAS latency modes.

A delay locked loop (DLL) in a semiconductor device, includes an clock buffer receiving an external clock signal and an inverted clock signal and outputting first and second internal clock signals to be used in the DLL circuit; and a variable clock divider receiving the second internal signal from the clock buffer and variably dividing the second internal clock signal to have a predetermined pulse width according to a control signal based on a column address strobe (CAS) latency, which is set according to a frequency of the external clock signal, wherein the control signal is initially set to have a first logic level and is enabled to a second logic level when the CAS latency corresponds to a high frequency.

The present invention discloses a circuit for generating a data strobe signal in a DDR memory device and a method therefor which can precisely distinguish preamble and postamble periods of the data strobe signal by generating pulses for generating the data strobe signal only in a data strobe signal input period by using an internal clock signal according to CAS latency under a read command, and generating the data strobe signal by using the pulses, and which can improve reliability of the circuit operation by precisely controlling operation timing with the internal clock signal.