| 摘要 |
A high-frequency circuit for use in a multiband wireless apparatus for switching the connection between an antenna and transmission/reception circuits depending on signals for pluralities of communications systems, comprising a single-pole, multi-throw switch circuit comprising FET switch circuits between a common port connected to an antenna-side circuit and pluralities of single ports connected to the transmission/reception circuits, and a first matching circuit connected to the common port; the first matching circuit comprising a first inductance element connected in series to a signal path between the antenna and the common port, and a first capacitance element connected to the first inductance element on the antenna side and grounded; the first inductance element making the impedance of the single-pole, multi-throw switch circuit inductive when the single port is viewed from the antenna side; and the first capacitance element adjusting impedance matching between the antenna-side circuit and the transmission/reception circuits. |
| 主权项 |
1. A high-frequency circuit for use in a multiband wireless apparatus for switching the connection between an antenna and transmission/reception circuits depending on signals for pluralities of communications systems used in a basic frequency band and higher frequency bands than the basic frequency band, comprising
a single-pole, multi-throw switch circuit comprising FET switch circuits between a common port connected to an antenna-side circuit and pluralities of single ports connected to the transmission/reception circuits, the connection between the antenna and the transmission/reception circuits being switched by controlling the ON/OFF state of each FET switch circuit, and a first matching circuit connected to said common port; wherein the impedance of the single-pole, multi-throw switch circuit is capacitive when viewing from said common port, wherein said first matching circuit comprises a first inductance element connected in series to a signal path between said antenna and said common port, and a first capacitance element connected to said first inductance element on the antenna side and grounded, wherein said first inductance element makes the impedance of said single-pole, multi-throw switch circuit inductive when said single port is viewed from said antenna side when at least a FET switch circuit, through which a higher frequency band passes, is controlled in an ON state, and wherein the capacitance of said first capacitance element is set depending on a synthesized equivalent capacitance of the FET switch circuits in an OFF state, whereby said first capacitance element adjusts impedance matching between said antenna-side circuit and said transmission/reception circuits. |
