Electronic products have certain requirements for ESD protection, and relevant electrostatic protection circuits are generally designed at ports that are easy to contact with the outside world to avoid damage to the products by static electricity. For wireless communication products, the relevant design circuits can generally be seen in antennas and other places.
This article collects the recommended design circuits of relevant chip manufacturers for your reference, and welcomes exchanges and supplements.
1, Skyworks introduces two classic protection circuits in its antenna switch Sky13638.
Static electricity is actually direct current, so the protection circuit must have a capacitor to block it, and it also needs to be equipped with an inductor to introduce it. "pi"and "T or L" type circuit form can be selected according to needs, and the capacitance value can also be adjusted according to the matching chip. However, the matching effect of the two ports of the L-type circuit is not as ideal as that of the Pi-type. The T-type will place two capacitors in series in the working link, and the corresponding link loss will be greater.
2. TDK also introduced the design of the protection circuit for the electrostatic sensitive chip of SAW in its SAW product GPS GLONASS Extractor Filter B4340.
for wideband filters the high-pass esd matching structure needs to be at least of 3rd order to ensure a proper matching for any impedance value of antenna and saw filter input. the required component values h**e to be determined from case to case.
TDK recommends that broadband SAW products have at least three third-order circuits for ESD protection and ensure an ideal impedance matching effect. Among them, the varistor should provide an ESD bleed-up path according to the voltage magnitude of the change resistance, and the suppressor diode is also a step-down to suppress the electrostatic voltage.
in cases where minor esd occur, following simplified “esd matching” topologies can be used alternatively.
For cases where the ESD hazard is relatively small, a lite protection circuit is recommended.
in all three figures the shunt inductor lp2 could be replaced by a shorted microstrip with proper length and width. if this configuration is possible depends on the operating frequency and **ailable pcb space.
For inductors in ESD circuits, LP2 can also be replaced with short microstrip lines (length and width parameters are adjusted according to the requirements of the scene). Of course, for some scenarios with relatively high requirements, it may be necessary to add some special ESD protection devices.
effectiveness of the applied esd protection has to be checked according to relevant industry standards or customer specific requirements
On the whole, the recommendations of these two companies for ESD protection circuits are relatively similar, and they can be used as references to each other.