| 摘要 |
A simply structured clock pulse generator operating stably in a wide range of frequencies in response to a timing signal fed from outside a semiconductor integrated circuit. A first frequency signal fed from the external terminal of the semiconductor integrated circuit and a second frequency signal generated within the semiconductor integrated circuit are input to a phase comparator. The output signal of the phase comparator is smoothed by a low-pass filter for conversion to a voltage signal. A compensation circuit uses both a delay signal from a current-controlled delay circuit receiving the first frequency signal and the first frequency signal to generate a current signal corresponding to the frequency of the latter signal. The voltage signal generated by the low-pass filter is converted into a current signal. This current signal is combined with the current signal from the compensation circuit to control the oscillation frequency of a ring oscillator comprising a current-controlled delay circuit the same in structure as the above current-controlled delay circuit. On the basis of the oscillation signal from the ring oscillator, the second frequency signal and clock signals needed in the semiconductor integrated circuit are generated.
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