| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a technique which allows for sufficient suppression of leakage of the RF signal to a drive circuit, while achieving high speed switching of the capacitance of a variable capacitance element, by estimating the potential at the terminal of the variable capacitance element connected with a RF circuit.SOLUTION: Leakage of RF signals to a drive circuit 1 can be suppressed sufficiently by a first resistor R1 for RF interruption. When a DC current I1 is measured by first current measurement means, potential at one terminal (connection point c) of a variable capacitance element C connected with the first resistor R1 can be estimated simply. Since the potential at one terminal of a variable capacitance element C can be adjusted in a state substantially free from control lag when the output voltage of a DC power supply Vdc is controlled based on the estimation potential, high speed switching of the capacitance of the variable capacitance element C, the capacitance of which changes depending on the magnitude of a DC voltage applied between both terminals, can be achieved.</p> |
