Precautions for using SMD transistors

Precautions for using SMD transistors

When using SMT transistors, the following 6 elements need to be noted:

1. Pay attention to the influence of bypass capacitance on voltage gain;

2. Pay attention to the influence of the junction capacitance inside the transistor. Due to semiconductor manufacturing processes, there will inevitably be a certain capacitance of junction capacitance inside the SMT transistor. When the input signal frequency reaches a certain level, they will greatly reduce the amplification effect of the SMT transistor, and worse, it will also cause additional phase difference as a result;

3. When serving as a switch, attention should be paid to its reliability;

4. Clearly grasp the cutoff frequency of the transistor;

5. The switching speed of SMT transistors is generally unsatisfactory;

6. It is necessary to understand the principle of an emitter follower. One of the biggest benefits of an emitter follower is its high input impedance, which enhances its load-bearing capacity and may cause unexpected "problem sources".