| 摘要 |
<P>PROBLEM TO BE SOLVED: To make precise process calibration for a short time without increasing a circuit area required for a process monitor. <P>SOLUTION: After a digital control oscillator 38 selects an arbitrary oscillation band, a control section 25 switches a switch 44 for a signal of a TDC 41 to be inputted to a process monitor control section 40. The TDC 41 converts a period between a rising edge of a signal VREF and a rising edge of the signal VPRE, closest to it, to a digital value, and a period between a rising edge of the signal VREF and a rising edge of the signal VPRE, second closest to it, to another digital value, and calculates a difference between the digital values. The process monitor control section 40 refers to a look-up table, and compares the calculated value with a preset expected value to determine a process value. The process values are outputted, respectively, to an adjustment control section 26 as a process signal, to perform process calibration. <P>COPYRIGHT: (C)2011,JPO&INPIT |
