| 摘要 |
A high-frequency switch is configured of first and second bipolar transistors connected into a cascode configuration. Current to be supplied from the collector of the second bipolar transistor at the subsequent stage is controlled by the "on" and "off" of a control signal which is received by the base of the transistor. Accordingly, the high-frequency switch operates as one which has a gain in its on-control mode and which has high isolation characteristics in its off-control mode. In addition, an adjustable high-frequency switch is configured by placing a plurality of high-frequency switches as described above in parallel. Herein, the bases of the first bipolar transistors are interconnected and receive a common input signal. The bases of the second bipolar transistors can select the destination the input signal is to be outputted by respectively receiving different control signals. By having the bases of the second bipolar transistors receive a common control signal, the adjustable high-frequency switch operates as a power divider in its on-control mode and as an attenuator in its off-control mode. Further, an adjustable high-frequency power amplifier is configured in such a way that the outputs of the adjustable high-frequency switch described above are respectively connected to the bases of third bipolar transistors whose emitters are grounded. The adjustable high-frequency power amplifier can lower power consumption by turning the respective control signals "on" and "off" in accordance with the required output power.
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