| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a digital DLL circuit with a simple configuration capable of easily obtaining a delay feedback value without using a phase comparator or the like and easily executing complicated control. <P>SOLUTION: The digital DLL circuit includes: a register 11 for holding a delay target value; a ring oscillator 12; a first counter 13 for counting an external reference clock RCLK for determining a measurement period; a second counter 14 for counting an oscillated output clock CLK of the ring oscillator 12 by each measurement period depending on the first counter 13; a digital control variable delay circuit 15; and a control circuit 16 that performs control of resetting, starting, and stopping as required of the first and second counters 13, 14 on the basis of control signals CTL1, CTL2, digitally calculates a count C2 of the second counter 14 and the delay target value DV of the register 11, and provides a result of the arithmetic operation to the variable delay circuit 15 as a delay control variable DCV on the basis of a count value C1 of the first counter 13. <P>COPYRIGHT: (C)2007,JPO&INPIT |
