TWO-FREQUENCY SWITCH, DEVICE USING TWO-FREQUENCY ANTENNA IN COMMON, AND MOBILE RADIO COMMUNICATION EQUIPMENT FOR TWO-FREQUENCY BANDS USING THE DEVICE

摘要

A two-frequency switch which is used for mobile radio communication of portable telephone, etc., and can be switched to turned-on/off states in two channels with a simple constitution. The two-frequency switch is composed of a parallel connected body of a PIN diode (101) and its compensation circuit (102) which is constituted of a circuit having at least two series resonance points and one parallel resonance point. Therefore, the impedance of the compensation circuit which is capacitive at a frequency as low as a direct current becomes inductive after passing through the first series resonance point and cancels the parasitic capacitance of the diode (101) in the first channel. In addition, the impedance again can become inductive after passing through the next series resonance point from the parallel resonance point and cancel the parasitic capacitance of the PIN diode (101) in the second channel.