An apparatus includes a plurality of impedance matching networks, a common port, a first switch circuit and a second switch circuit. The impedance matching networks may be (i) connected in series between an input port and an output port and (ii) configured to generate a power detection signal in response to a radio-frequency signal. The radio-frequency signal may be a transmit signal or a receive signal. The common port may be (i) connected to the impedance matching networks and (ii) connectable to an antenna. The first switch circuit may be configured to switch the input port and a circuit ground potential. The second switch circuit may be configured to switch the output port and the circuit ground potential.