| 摘要 |
PURPOSE:To attain frequency discrimination within a wide frequency range by comparing charges stored in two capacitors at a comparator so as to discriminate the frequency. CONSTITUTION:While a reset pulse is inputted to a reset signal input terminal 2, an N-channel MOS transistor(TR) 11 is turned on and a switch 5 is turned off. That is, a noninverting input terminal of a comparator 10 goes to an L level. On the other hand, a switch 4 is closed by the reset pulse. Then a data clock signal A inputted to a data signal input terminal 1 in this case is inputted to a time constant circuit comprising a resistor 6 and a capacitor 7, and after the reset is released, the switch 4 is opened. Since the width of the reset pulse is equal to one cycle of a data clock signal A, the charge by one clock pulse is stored in the capacitor 7. Thus, an inverting input terminal of the comparator 10 goes to an H level and a noninverting input terminal goes to an L level for a block N1, then an output signal C of the comparator 10 goes to an L level and an output signal D of a binary flip-flop circuit 13 goes to an L level. |
