HIGH FREQUENCY SWITCH

摘要

PROBLEM TO BE SOLVED: To provide a SPnT type high frequency switch for suppressing leakage in an open switch state. SOLUTION: When a desired high frequency signal is transmitted from a Port-1 to a Port-2, it is required that the impedance when viewed from the right is equal to the impedance when viewed from the left from the Ports 1, 2 respectively. In this case, it is required that the real parts of the impedances Z3, Z4are equal to each other and the imaginary parts of the impedances Z3, Z4are in a conjugate relation in Fig.B. When the capacitance of a variable capacitor Cvarireaches a high capacitance CH, a switch circuit 201 is switched on. When the transmission of the desired high frequency signal is shut off from the Port-1 to the Port-2, it is required that an impedance Z5is to be a high impedance. In this case, since a relation of Z6=1/jωC4holds, the capacitance of a fourth capacitor C4is decreased to the utmost to bring the Z6to a high impedance. Further, when the impedance Z5reaches a high impedance, it is solved by making Z2zero and bringing Z3to a high impedance. The switch circuit 201 is switched off when the capacitance of the variable capacitor Cvarireaches a low capacitance CL. COPYRIGHT: (C)2006,JPO&NCIPI