479 results about "Clock buffer" patented technology

A memory device minimizes the skew between an external clock and a DQS (or DQ) after the locking state by regulating a delay ratio of a replica delay model to compensate errors of process, temperature or voltage change. The memory device comprises: an input clock buffer for buffering an externally inputted external clock to generate an internal clock; a DLL for delaying the internal clock to synchronize a phase of the external clock with that of a DQS; an output clock buffer for buffering an output clock outputted from the DLL; and an output control unit for generating the DQS using a clock outputted from the output clock buffer. Here, the DLL comprises a replica delay model for modeling delay factors of the input clock buffer and other delay factors until the output clock outputted from the delay line is outputted to the outside of a chip, and for regulating a delay ratio in response to a plurality of control signals inputted externally in a test mode.

A novel iterative latch placement scheme wherein the latches are gradually pulled by increasing attraction force until they are eventually placed next to a clock distribution structure such as a local clock buffer (LCB). During the iterations, timing optimizations such as gate sizing and re-buffering are invoked in order to keep the timing estimation accurate. By applying the iterative clock net weighting adjustment, the present invention allows tighter interaction between logic placement and clock placement which leads to higher quality timing and significant power savings.

A delay-locked loop (DLL) of an integrated circuit (IC) with testing circuitry and a method for testing a DLL. During test mode, a phase comparator of the DLL receives a test clock in place of the reference clock and determines the phase difference between the test clock and the dock fed back to the DLL from a clock buffer tree. A variable delay element of the DLL then shifts the reference clock in time by an amount that depends on that phase difference. The variable delay element can be exercised by varying the phase of the test clock with respect to the reference clock by a known phase offset to cause the variable delay element to produce a range of delays. Whether the variable delay element is functioning properly can be determined by checking whether the phase of the test clock is aligned with the phase of the feedback clock.

A clock control circuit includes a multiphase clock generating circuit receiving an output signal of a input buffer for generating multiphase clocks; a selector circuit receiving multiphase clocks output from the multiphase clock generating circuit for selecting one of the multiphase clocks; a first variable delay circuit for delaying the output of the selector circuit; a clock buffer dummy receiving the output signal of the variable delay circuit; a phase comparator circuit for detecting a phase difference between an output from the multiphase clock generating circuit and an output of the clock buffer dummy; and a filter for smoothing the output of the phase comparator circuit. The first variable delay circuit has its delay time varied by the output of the filter. The clock control circuit further includes a second variable delay circuit, receiving the output signal of the input buffer, having its delay time varied by the output of the filter; an adder circuit for adding the filter output and an input set value; a third variable delay circuit, receiving the output signal of the input buffer, having its delay time varied by the output of the adder circuit; and clock buffers receiving output signals of respective ones of the second and third variable delay circuits.