DLL CIRCUIT WITH MASTER-SLAVE STRUCTURE

摘要

PURPOSE: A DLL(Delay Locked Loop) circuit with a master-slave structure is provided to generate an internal clock by using a received external clock. CONSTITUTION: A phase comparator(322) of a master DLL(32) generates a detection signal(DS) by comparing an external clock(ECLK) with a phase of a feedback signal(FD). A delay control portion(324) receives the detection signal(DS) and generates the first delay control signal(DCON1). The first digital delay portion(326) delays the external clock as much as a delay time according to the first delay control signal(DCON1). A compensating delay portion(328) delays an output signal of the first digital delay portion(326) as much as a compensating time and generates the feedback signal. A digital filter(342) removes a high frequency component from the first delay control signal(DCON1) and generates the second delay control signal(DCON2). The second digital delay portion(344) delays the external clock(ECLK) as much as the external clock(ECLK) according to the second delay control signal(DCON2). and generates an internal clock(ICLK).