| 摘要 |
PURPOSE:To obtain a frequency comparator with stable operation by a simple constitution, by constituting the circuit with 5 FF circuits, 4 NOR gates and 2 AND gates. CONSTITUTION:Two inputs of an FF100 are connected to input terminals A, B, via coincidence gates 7, 8 consisting of NOR gates and a combination circuit of FFs 200,300. The output of the FF100 is connected to one input of AND gates 3, 4, via coincidence gates 13, 14 consisting of NOR gates and a combination circuit of FF400, and the output of the gates 7, 8 is connected to another input of the gates 3, 4, and the output of the gates 3, 4 is inputted to an FF500 for high and low comparison of frequency, respectively. When the input frequency at the terminal A is higher than that at the terminal B, the output of the gates 7, 3 is at H level, a terminal C is at H and a terminal D is at L level. When the input frequency at the terminal B is higher than that at the terminal A, the gates 7, 3 are inverted, resulting that the terminal D is at H and the terminal C is at L level, and the input frequency can be compared with the level of the terminals C, D. |
