A transmit-receive switch has a transmit port, an antenna port, and a receive port. A first switch couples the transmit port to the antenna port when a signal TxON is asserted. A LOW_BAND signal indicates the selection of a lower band of frequencies. A tuning structure is formed by a second and third switch in series which couple the antenna port to ground through a first capacitor when TxON and LOW_BAND are both asserted, and LOW_BAND may be provided to one or more such tuning structures for multi-band frequency operation. A second capacitor couples the antenna port to ground when a fourth switch is enabled. An inductor couples the antenna port to the receive port. A third capacitor is placed across the receive port and ground. A fifth switch is closed when TxON is asserted. The first through fifth switches can be a CMOS FET with an isolated substrate coupled to ground through an associated resistor.