| 摘要 |
PURPOSE:To detect the large/small relation between signal frequencies by comparison with high precision by providing two circuits which vary in resistance value with the frequency of an input signal and have a positive and a negative equivalent resistance, an integrating the composite current of output currents of those two circuits. CONSTITUTION:A negative switched capacitor circuit 10 has its resistance value set according to a frequency to be compared with a reference frequency and also has the negative equivalent resistance, and a positive switched capacitor circuit 20 has its resistance value set according to the reference frequency and also has the positive equivalent resistance. A constant DC voltage V is applied to one-side terminals of those two switched capacitor circuits 10 and 20 in parallel. The other-side terminals of the switched capacitor circuits 10 and 20 are connected in common so as to obtain the composite current of the output currents of those circuits 10 and 20, and the composite current is integrated 3. A frequency shift is detected from the integral value. |
