| 摘要 |
PURPOSE:To detect a shift in signal frequency with high precision by providing two circuits which vary in resistance value with a signal frequency and have a positive and a negative equivalent resistance, and detecting the composite current value 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 value of the output currents of those circuits 10 and 20, and the value of the composite current flowing through the common-connection point is detected by a circuit 30. A frequency shift is detected with the output of the circuit 30. |
