Duplexers integrated with Electrostatic Discharge (ESD) protection diodes on the receiver (Rx) port are specially designed to solve the electrostatic damage problem of sensitive RF receiving circuits in complex application environments. The Rx channel of RF transceivers is extremely sensitive to external electrostatic pulses and surge voltages. Static electricity generated by human contact, equipment friction, and environmental electromagnetic induction can generate instantaneous high voltage of several kilovolts, which will break down the precision resonator chips and sensitive circuit structures of the duplexer, causing permanent device failure and transceiver system paralysis. Integrating ESD protection diodes on the Rx port is an efficient and miniaturized protection solution.

The working principle of Rx-port ESD protection duplexers is to use high-speed low-capacitance ESD diodes to absorb and release instantaneous static surge energy. The ESD protection diodes are tightly integrated at the Rx output port of the duplexer, with ultra-low parasitic capacitance design to avoid affecting the RF signal transmission performance of the receiving channel. Under normal operating conditions, the ESD diodes are in a cut-off state, with no impact on the passband insertion loss, isolation, and frequency selectivity of the duplexer. When instantaneous electrostatic high voltage invades the Rx port, the diodes are rapidly turned on to conduct static current to the ground, clamp the port voltage within a safe range, and protect the internal duplexer structure and subsequent LNA chips from electrostatic damage.

This integrated protection design has significant advantages over discrete ESD protection schemes. The on-chip integrated ESD diodes realize miniaturized integration, saving board space and eliminating parasitic loss caused by discrete device wiring. The ultra-low capacitance characteristic of customized RF ESD diodes ensures that the receiving channel has excellent high-frequency performance, with no deterioration of signal sensitivity and bandwidth indicators. This type of duplexer is widely used in portable electronic devices, vehicle-mounted communication equipment, and industrial wireless terminals with complex electrostatic environments. It effectively improves the anti-static capability and environmental adaptability of RF front-ends, reduces equipment failure rates, and prolongs the service life of communication devices.