2013 Question D (Undergraduate): Radio Frequency Broadband Amplifier (1)

RF wideband amplifier function: When the input signal is less than or equal to 1mVrms, through the amplification circuit, the output is greater than or equal to 1Vrms to achieve signal amplification and other functions. Design: This project has three levels of amplification. The first level is based on the ERA-8SM chip small signal amplification. Because signals of less than or equal to 1mVrms need to be amplified, low-noise small signal amplification chips are the best, and ERA-8SM fits the bill perfectly and can amplify 20db; the second level is program-controlled amplification based on the VCA821 chip. Because the entire system needs to be able to adjust the amplitude of the signal, and the gain of the VCA821 can be adjusted from -40db to 20db, plus the fixed gain amplification of the subsequent stage can adjust the signal from 0 to 60db; the third stage is based on OPA695 fixed gain amplification. The gain of the first two stages can reach 40db, and the system requirement reaches 60db, so this stage can amplify 20db to make the entire system meet the requirements. System debugging video address: https://www.bilibili.com/video/BV1Vv411i7f7/