RF DEVICE WITH A TRANSMIT/RECEIVE SWITCH CIRCUIT

摘要

A transmit/receive switch circuit has a comprises a controllable transmit section and a controllable receive section, having an output and an input coupled to an RF transmit/receive terminal respectively. The transmit section comprises a first transistor having a main current channel coupled between an RF transmit signal input and the RF transmit/receive terminal. The receive section comprises a first transistor having a main current channel coupled between the RF transmit/receive terminal and a RF receive signal output and a second transistor having a main current channel coupled between the RF receive signal output and ground. A signal that is derived from an RF input signal at the RF transmit/receive terminal is rectified. The rectified signal is used to control a control electrode of the second transistor of the receive section to make this transistor increasingly conductive with increasing RF signal amplitude. The rectified signal may also be used to control a control electrode of the first transistor of the transmit section in this way. Thus, the transmit/receive switch circuit is made to perform a limiting function.