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High frequency triode

High frequency triode

Introduction to product description: High-frequency transistors are generally used in high-frequency broadband low-noise amplifiers such as VHF, UHF, CATV, wireless remote control, and RF modules. Most of these applications are used under low voltage, small signal, small current, and low noise conditions. The maximum power is 2.25 watts, and the maximum collector current is 500 mA. The principle of selection during use is (1) When the ambient temperature of the transistor is higher than 30℃, the power dissipation Pcm should be derated by 60-80%. . (2) The triode should be as far away from the heating element as possible to ensure that the triode can work stably and normally.

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product description:

High-frequency transistors are generally used in high-frequency broadband low-noise amplifiers such as VHF, UHF, CATV, wireless remote control, radio frequency modules, etc. These applications are mostly used under low voltage, small signal, small current, and low noise conditions, and their maximum power is 2.25 Watt, the maximum collector current is 500 mA, and the selection principle during use is:

(1) When the ambient temperature of the transistor is higher than 30℃, the power dissipation Pcm should be derated by 60-80%.

(2) The triode should be as far away from the heating element as possible to ensure that the triode can work stably and normally.

(3) Among the parameters of the triode, some parameters are easily affected by temperature, such as iceo, ubeo and β value. The changes of iceo and ubeo with temperature are as follows:

① When the temperature increases by 6℃, the iceo of the silicon tube will double;

②Every time the temperature increases by l0℃, the iceo of the germanium tube will double;

③The change of silicon tube ubeo with temperature is about 1·7mv/℃.

⑷If you use the low voltage of 3V, 5V, the breakdown voltage should not be too large. If the breakdown voltage is too large (above 15V), the linearity at low voltage will be poor, which will affect the use.

⑸ When the input signal is weak, it is recommended to use the 2SC3356 with a smaller insertion gain for the primary amplification, and the BFQ591 or 2SC3357 with the larger gain for the secondary amplification.

⑹The cut-off frequency fT of the selected high-frequency transistor should be one-eighth to one-tenth of the actual frequency used to reduce the insertion noise during use and increase the gain.

(7) For triodes used in high-frequency or microwave circuits, in order to reduce parasitic effects, the lead wires should be as short as possible, and it is best to use surface mount packages.

(9) In order to prevent the secondary breakdown of the power transistor, it is necessary to avoid using loads with excessive reactance components.

(10) On the premise that the required amplification parameters of the whole machine can be met, a triode with appropriate insertion gain and DC amplification coefficient hfe should be selected to prevent self-excitation. Generally, the primary amplification requires a small insertion gain, and its DC amplification coefficient hfe should be selected larger, and the secondary amplification requires a large insertion gain, and its DC amplification coefficient hfe should not be too large.

(11) When the high-frequency transistor is connected to the circuit, the base should be connected first. Do not disconnect the base circuit when the collector and emitter have voltage.

(12) There are many types of high-frequency triodes, so the type of triode should be determined according to the requirements of the specific circuit, and then selected according to the main parameters of the triode.


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