| 摘要 |
PURPOSE:To obtain a stable sampling pulse synchronously surely with a synchronizing signal by providing a delay element to a negative feedback path and using a pulse oscillator whose oscillation is controlled in response to the synchronizing signal. CONSTITUTION:The pulse oscillator 18 is provided with an OR gate 20, a delay element 22 and a multiplexer (MUX) 24. Since the output signal B of a synchronizing separator circuit 14 is given to the input terminal of the OR gate 20, the synchronizing signal B is at a high level during synchronizing signal periods T1-T2 and the inverting output level of the OR gate 20 is at a low level independently of the output level of the multiplexer 24. When the synchronizing signal B goes to a low level at the point of time T2, the inverting output of the OR gate 20 goes immediately to a high level. The high level is given to the input terminal of the OR gate 20 after a selected delay time elapses. Since the oscillation is executed by utilizing the delay element digitally, the accuracy and stable oscillation decided by the delay time is obtained just after the point of time T2.
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