TUNED RING OSCILLATOR CIRCUIT

摘要

PURPOSE: To produce a time reference signal tuned to a variable system reference signal. CONSTITUTION: An oscillator circuit 20 is tuned to the spindle index pulse of a rotary magnetic storage disk device, for example. A ring oscillator circuit 20 includes a serial transmission gate. This gate is controlled by the output given from a programmable delay line and interrupts the operation of the ring oscillator 22 to perform the fine control of the frequency of the ring oscillator 22 according to the program steps. The output signal of the ring oscillator 22 is divided by a programmable divider 40 to perform the rough control of frequency against an output pulse. The frequency of the output pulse is compared with that of the device reference pulse. Based on this comparison result, a control signal is produced by a microprocessor to the ring oscillator 22.