Background：

In view of global warming and the increase in thunderstorms, radio frequency equipment placed outdoors is more likely to be struck by lightning. The transmission rate of the RF port can generally be as high as 1 Gbps, so it will have higher requirements for junction capacitance. Depend on this situation, we have designed a RF port protection solution using ceramic gas discharge tubes (GDTs) and transient voltage suppression diodes(TVS Diodes).

SOCAY's Protection Solution and Electronics Components:

Gas Discharge Tube(GDTs)

Gas Discharge Tube) is the most widely used switching device in lightning protection equipment. Lightning protection of AC and DC power supply and lightning protection of various signal circuits can be used to discharge lightning current into the ground. Its main features are: large discharge current, small inter-electrode capacitance (≤3pF), high insulation resistance (≥109Ω), large breakdown voltage dispersion (±20%), and slow reaction speed (the fastest is 0.1 ~ 0.2 μs). According to the number of electrodes, there are two-pole discharge tube and three-pole discharge tube (equivalent to two two-pole discharge tube in series).  Its shape is cylindrical, there are two types of structure with lead and without lead.

GDT【SC1812-90CSMD】DC Spark-over Voltage：90V±20%，Nominal Impulse Discharge Current（8/20μS）：2kA，Maximum Capacitance＜1.0pF，Minimum Insulation Resistance >1GΩ; 

GDT【SC2E5-90LSMD】DC Spark-over Voltage：90V±20%，Nominal Impulse Discharge Current（8/20μS）：5kA，Maximum Capacitance＜1.0pF，Minimum Insulation Resistance >1GΩ; 

Transient Voltage Suppressor(TVS)

Transient Voltage Suppressor referred to as TVS tube. The electrical characteristics of the TVS diodes are determined by the P-N junction area, doping concentration and wafer resistance. Its surge current capability is proportional to its P-N junction area. TVS diodes is widely used in the protection of semiconductors and sensitive devices, usually used for the protection of secondary power and signal circuits, and anti-static. It is characterized by fast reaction speed (PS level), small size, large pulse power, low clamp voltage. Its 10/1000μs wave pulse power is from 400W to 30KW, and the peak pulse current is from 0.52A to 544A; the breakdown voltage has a series value from 6.8V to 550V, which is convenient for circuits with different voltages.  

TVS【ESD03V32D-LC】Vrwm：3.0V；Vb：4.0V；Vesd：8KV/15KV；Ct（f=1MHz）：0.8pF；Package: SOT-323

Application:

1. Medical devices

2. Video monitoring

3. Optical transmitter

4. Other RF equipment

Solution Notes:

1. The solution use a GDT in the front end.It is connected in parallel between signal line and ground line to attenuate very large surge currents.

2. The TVS junction capacitance at the back end is 1.2pF, which does not affect the data transmission; 

4. the package is SOD-323, which is small in size and saves cost; the residual voltage is low, which effectively protects the RF chip

3.The solution meets the surge standards such as I EC61000-4-5 and GBT17626.5

For more circuit protection solutions, please go directly to the SOCAY to consult the online customer service http://www.socay.com/.