| 摘要 |
PURPOSE: A band switching circuit is provided to easily select one of UHF or VHF terminal using one terminal of microcomputer. CONSTITUTION: A band switching circuit includes a microcomputer(10) driving a transistor(Q3) for switching according to the user selection. An RF signal of an input circuit(40) is inputted to a gate(G1) of a first dual gate FET(TR1), and a power voltage (Vcc) provided from resistors(R4,R5) is provided to a gate(G2), and a drain(D) is coupled with UHF band processing circuit(21). An RF signal of an input circuit(40) is inputted to a gate(G1) of a second dual gate FET(TR2), and a power voltage(Vcc) provided from resistors(R1,R2) is provided to a gate(G2), and a drain(D) is coupled with VHF band processing circuit(31). A diode(D3) controls a driving operation of the first and the second dual gate FER(TR1,TR2) according to the operation of the transistor(Q3). |
