| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To facilitate the control of a gain control circuit of a high frequency circuit block and to reduce the frequency dependence of a gain control characteristic by a mobile communication terminal corresponding to a multiband. <P>SOLUTION: The gain control circuit of the high frequency circuit block comprises a FET 240 inserted in a series position with a signal line connecting a signal input terminal 231 and a signal output terminal 232; FETs 245 and 251 inserted in parallel with the signal line; two reference voltage terminals 234 and 235; and one control terminal 233. Reference voltages Vref1 and Vref2 and a control voltage Vc are applied to the three FETs 240, 245 and 251, respectively, while the FETs 240, 245 and 251 are made to serve as variable resistors. As such, the gain control circuit is constructed. Further, resistors 241, 244, 247, 250 and 253 are respectively connected to the PETs 240, 245 and 251 to minimize influence by the frequency characteristic of a passage characteristic of the FETs 240, 245 and 251. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
