| 摘要 |
In a phase shifter for digitally shifting the phase of an RF (Radio Frequency) signal by changing a switched line which is connecting two main lines into another switched line, at least one of the switched lines is always connected to one of the main lines so as to operate as an open stub when the RF signal is not passed through the switched line. A concrete example of the phase shifter includes a first main line, a second main line which is placed a predetermined distance apart from the first main line, a first switched line which is placed between the first main line and the second main line, a second switched line which is placed between the first main line and the second main line and which is always connected to the second main line, a first switch for controlling the connection/disconnection between the first main line and the first switched line, a second switch for controlling the connection/disconnection between the second main line and the first switched line, and a third switch for controlling the connection/disconnection between the first main line and the second switched line. The second switched line operates as the open stub when the RF signal is not passed through it, thereby phase shift deviation is reduced and phase shift-frequency relationship is improved. In addition, the number of switches can be reduced in comparison with a conventional switched line phase shifter.
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