If you've seen what a printed circuit board looks like before, you know that there are many components on a printed circuit board. The one-stop PCB assembly company installs these pcb components on the bare pcb board in various ways. These components are an important part of the circuit board. FS Tech will introduce you to several particularly important PCB components.

PCB component one: varactor diode

The varactor diode is specially designed according to the principle that the capacitance can change with the change of the applied reverse voltage. It is more capable than conventional diodes. This special diode is generally used in high-frequency modulation circuits such as mobile phones. It can modulate low-frequency signals to high-frequency signals and transmit them. During operation, the voltage of the varactor diode is generally added to the negative electrode, so that the internal junction capacitance of the varactor diode changes with the change of the modulation voltage.

When the varactor diode fails, the following two situations mainly occur:

1. When leakage occurs: the high-frequency modulation circuit will not work or the modulation performance will deteriorate.
2. When the variable capacitance performance becomes poor: the operation of the high-frequency modulation circuit is unstable, and the information received by the other party will be distorted.

When one of the above situations occurs, FS Technology recommends that you replace the varactor diode of the same type. We have strong pcb component procurement ability, if you want to assemble this special pcb original to your pcb board, FS Technology is happy to serve you. We're pretty good at dealing with these varactors.

PCB Component 2: Transistor

In PCB components, it is usually represented by "Q" plus a number, for example: No. 17 transistors are represented by Q17.

Features of transistors

There are 2 PN junctions inside, and this pcb component has amplification capability. There are two types of transistors: NPN type and PNP type. Generally speaking, on an assembled PCB you will find two types of transistors, NPN and PNP, to make them complement each other. The so-called pair tube in the OTL circuit is paired with the PNP type and the NPN type. The components used in the PCB board used in the phone are usually: A92, 9015, A42, 9014, 9018, 9013, 9012 and other models.

PCB component three: FET

It can be extremely low noise and a high degree of input impedance. A FET is a voltage-controlled element, while a transistor is a current-controlled element. When your PBC board only allows a small current to pass, FS Technology recommends that you should choose a field effect transistor. The transistor is selected when the voltage is low and the signal is poor. 

More knowledge of important PCB components can be found in FS Technology's PCBA blog.