| 摘要 |
PURPOSE:To eliminate the shift in edge timing due to the transfer characteristics of a signal transmission system, by performing synchronism through the extraction of only a falling edge in the timing permissible on signal format. CONSTITUTION:An input digital signal 1 is inputted to a falling edge detecting circuit 2, where a falling edge signal 3 is produced. The signal 3 clears a counting circuit 5. The circuit 5 counts a signal 4 other than the clear time and its output 6 is detected 7 to input a decode output 8 to an OR gate 20. The output of a gate 20 is latched to a latch circuit 10 in the timing of a signal 9, a latch output 11 and the signal 3 are made coincident at an AND gate 12 and a coincident output 13 is taken as a phase synchronizing signal to a start-stop type synchronizing circuit 15 to produce a data strobe pulse 16. An output 17 of the circuit 15 is decoded at a decoder 18, a decode output 19 is inputted to a gate 20 and an OR output 21 is inputted to the circuit 10. Thus, an abnormal edge is eliminated and a signal of the falling edge next to the abnormal edge passes through as the phase synchronizing signal. |
