| 摘要 |
PROBLEM TO BE SOLVED: To provide an oscillation circuit ensuring a stabilized oscillation frequency regardless of variation in power supply voltage, ambient temperature or manufacturing process. SOLUTION: The oscillator comprises a means for counting the number of clocks at current oscillation frequency during the "H" level period or "L" level period of an "H" level signal or an "L" level signal having a predetermined period when it is inputted externally, and a means for storing the number of clocks in association with a digital value for current control, and regulates bias voltages PBIAS and NBIAS to the transistors 31 and 33 of a ring oscillator 20 by controlling mirror currents A and B flowing through a current control circuit 20 depending on the digital value. A digital value corresponding to the count of the count means is fed back, as a frequency regulation control signal, to the current control circuit 20 using a Look Up Table as a storage means thus regulating the oscillation frequency. COPYRIGHT: (C)2006,JPO&NCIPI
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