| 摘要 |
<p>PROBLEM TO BE SOLVED: To realize a self-oscillating function that supplies a clock signal, whose spurious radiation noise is suppressed without the need for adjustment by an externally mounted component. SOLUTION: Two tri-state inverters 22, 23 are provided as oscillation inverters and a value set to an inverter control register 28 is used to control whether or not the outputs of the inverters to be set to a high impedance. Two resistor circuits 25, 26 are provided and a value set to a resistor control register 27 is used to control whether or not which of the circuits 25, 26 is to be used for a feedback resistor circuit of the oscillation circuit. Moreover, in order to eliminate a noise signal, included in an oscillated signal Sosc1 obtained from the oscillation circuit as above, a filter circuit 21 is provided, that is a plurality of stages of L-shaped RC circuits connected in cascade, and number of the stages of the L-shaped RC circuits to be connected is controlled by analog switches 10, 11, based on the values set to filter control registers 13f1-13fn.</p> |
