Design Scheme of High Frequency Small Signal Amplifier

With the continuous development of science and technology, radio technology is widely used in various fields of national economy, military and people's daily life, and the technical level is higher and higher. In the radio communication system, electrical signals are radiated to space in the form of electromagnetic waves through wireless. Therefore, in radio technology, we often face such problems. The received signal is very weak, and it is easy to be disturbed by other signals and noise. Moreover, in long-distance communication and transportation, the signal will also decay and, and the signal reaching the receiving equipment becomes very weak, so it is difficult to ensure the accuracy of information. Therefore, in the transmission process, the received signal shall be selected and amplified to ensure the accuracy of the information transmitted to the receiving equipment and reduce errors. In this way, it is necessary to use high-frequency small signal tuning amplifier. It can sense many weak high-frequency small signals (the input signal voltage is generally near the order of uV to mV), and then use the LC resonant circuit as the frequency selection network and the amplification of the triode to select the useful frequency signal for amplification, and suppress the useless frequency signal. Therefore, the high frequency small signal resonant amplifier at the receiver is an important circuit of radio communication equipment. This paper briefly analyzes the design principle of high frequency small signal, LC oscillator and high frequency power amplifier circuit. At the same time, this paper also studies the parameter setting method of each circuit. The designed resonant amplifier is mainly composed of amplifier and tuning loop. In addition, in the design process, this paper first carries out the circuit simulation on Multisim10 circuit simulation software, then draws the schematic diagram combined with the actual situation, buys components and draws the PCB circuit diagram, and finally carries out the physical production and debugging. In the actual circuit, this paper adopts the 10MHz mid cycle instead of the difficult to adjust LC frequency selection circuit, utilizes the s9014 triode to amplify the amplification link, and selects a potentiometer for the emitter resistance to adjust the emitter resistance to change the amplification gain of the amplifier. Simulation and physical debugging results: the resonant frequency is 10MHz, and the circuit also has a certain gain, indicating that the design has been successful.