IMPEDANCE CONVERTER CIRCUIT AND COMMUNICATION TERMINAL DEVICE

摘要

An impedance converter circuit includes a transformer with a primary coil connected to a power feed port, a phase shifter circuit connected between a secondary coil of the transformer and an antenna port, and a bypass circuit connected between the power feed port and the antenna port. In a high band, an absolute value of impedance of the transformer viewed from the antenna port via the phase shifter circuit is higher than an absolute value of impedance of the bypass circuit. In a low band, the absolute value of the impedance of the transformer viewed from the antenna port via the phase shifter circuit is lower than the absolute value of the impedance of the bypass circuit.

主权项

1. An impedance converter circuit for use in an antenna device that transmits and receives a high frequency signal in a frequency band range including a first frequency band and a second frequency band whose frequency band range is higher than the first frequency band, the impedance converter circuit comprising:
a transformer including a primary coil and a secondary coil, the primary coil being connected to a power feed port; a phase shifter circuit connected between the secondary coil of the transformer and an antenna port; and a bypass circuit connected between the power feed port and the antenna port; wherein in the second frequency band, an absolute value of impedance of the transformer viewed from the antenna port via the phase shifter circuit is higher than an absolute value of impedance of the bypass circuit; and in the first frequency band, the absolute value of the impedance of the transformer viewed from the antenna port via the phase shifter circuit is lower than the absolute value of the impedance of the bypass circuit.