| 摘要 |
<p>PURPOSE:To determine the output frequency of a VCO only with a power source voltage, a frequency control voltage, and a time constant by providing an analog switch circuit between the output of an operational amplifier and the in-phase input of the operational amplifier. CONSTITUTION:An analog switching circuit 2 is provided between an output (a) of an operational amplifier 1 and an in-phase input (b) of the operational amplifier 1. Its turning-on/off is controlled by the voltage of this output (a), and an external control signal Vi is applied to the in-phase input (b) when it is turned on. When it is turned off, a bias V0 due to a bias generating circuit 3 is applied to the in-phase input (b). When a positive power source voltage VC is applied to a gate input (g) of the switching circuit 2, the circuit 2 is turned on, and the signal Vi applied to a terminal (e) is led out to a terminal (f). When a negative power source voltage VE is applied to the gate input (g), it is turned off. Thus, the output frequency of the VCO is determined only by the power source voltage, the frequency control voltage, and the time constant.</p> |
