RF VARIABLE GAIN AMPLIFYING DEVICE

摘要

PURPOSE: A RF variable gain amplifying device is provided which prevents varying isolation when an RF switch element provided in a signal bypass circuit is in the OFF state. CONSTITUTION: An RF variable gain amplifying device(1A) comprises an amplifying circuit(10), a switch element(22) connected in parallel with the amplifying circuit, and a resistor(23) connected in parallel with the amplifying circuit and with the switch element. The amplifying circuit does not operate when the switch element is in an ON-state but operates when the switch element is in an OFF-state. A potential at each of input and output terminals of the switch element is lower when the switch element is in the ON state than when the switch element is in the OFF state.