| 摘要 |
PURPOSE: A variable band pass filter is provided to selectively filter a desired signal by band-pass filtering an amplified signal. CONSTITUTION: A switch at a bank terminal, which has bandwidth, is switched on. According to the switching operation, a specific frequency band, which is filtered through a bandpass filter, is changed by using the capacitor value of a fixed capacitor(205) and a capacitance value of a corresponding bank. The switch is combined with a space between a capacitor at the bank terminal and the ground. By controlling a voltage supplied from a power supply part, the internal capacitor value of a varactor diode(203b) is determined. By using the determined capacitor value, a central frequency in a specific band is minutely adjusted. |
