Time-delay locking loop circuit for internally correcting dutyratio and method for correcting duty cycle thereof

Abstract

A delay locked loop (DLL) circuit having a duty cycle corrector (DCC) that has a broad range of duty cycle correction, consumes only a small amount of power, has few restrictions on operating frequency, and improves the characteristics of a memory device is described. The delay locked loop circuit includes an additional loop for duty cycle correction as well as loops for controlling a rising edge and a falling edge of output signals. Thus, the delay locked loop circuit can internally correct the duty cycle without the use of a phase blender.

Description

[0001] This application claims priority from Korean Patent Application Serial No. 2002-60814 filed with the Korean Intellectual Property Office on October 5, 2002, the disclosure of which is hereby incorporated by reference in its entirety. technical field [0002] The invention relates to a delay locked loop (Delay Locked Loop, DLL) circuit, in particular to a DLL for internally modifying the duty cycle and a method for modifying the duty cycle. Background technique [0003] In data transmission between, for example, a memory device and a memory controller, by synchronizing the data with a clock signal before sending the data, the bus load and the transmission frequency increase. Therefore, it is increasingly important to synchronize data with a clock signal. That is, the time required to load data onto the bus in response to a clock signal is compensated to place the data on the edge or center of the clock signal. Between a phase locked loop (PhaseLocked Loop, PLL) circui...

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Problems solved by technology

[0009] However, the duty ratio correction method using the phase mixer 20 has the following defects: First, the range of DCC is related to the slope of the signals IN1 and IN2

If the duty cycle of an external clock signal ECLK has a ratio of 40 to 60 or 60 to 40, the DCC may not work properly and at the same time the power consumption increases, which limits the operating frequency

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