| 摘要 |
PROBLEM TO BE SOLVED: To enable high frequency section of the transmission section of a portable phone terminal to control gain linearly (flatness±1 dB) over a wide range of 70 dB or higher with respect to one control voltage. SOLUTION: An attenuator is configured as in the following to allow the high frequency section of the transmission section of a portable phone terminal to control a gain over a range of 70 dB or higher. That is, a high frequency signal input section 34 and a signal output section 35 are interconnected by a signal line 55 consisting of at least two series variable resistors 51, 52 parallel variable resistors 53, 54 are connected among the signal input section 34 and the signal output section 35 and a ground line 57 respectively to connect a gain control line 56 to variable resistors 51, 52, 53, 54, reference voltage application sections 23, 27, 31, 33 are connected to the variable resistors 51, 52, 53, 54 respectively, and a gain control voltage application section 19 is connected to the variable resistors 51, 52, 53, 54 respectively via the gain control line 56.
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