实验三 多级放大器与负反馈放大器.doc

实验三 多级放大器与负反馈放大器 Experiment three multistage amplifier and negative feedback amplifier First, the purpose of the experiment 1. grasp the relationship between amplifier amplification and amplification at all levels 2. learn how to introduce negative feedback in an amplifier circuit 3. the influence of negative feedback on the dynamic characteristics of the amplifier is tested experimentally Two 、 experimental instruments and devices 1. experimental instruments DC regulated power supply, function generator, digital oscilloscope and multimeter 2. experimental devices Table 3.1 experimental devices Three, preview requirements 1. review the contents of multistage amplifier and negative feedback amplifier in the textbook. Adjust the RW1 to make ICQ1=1.0mA 2. assumptions in the experiment, the 1 amplifier circuit to estimate the static working point data (beta = 200, rbb= 300, UBE = 0.7V) in table 3.2. 3. calculate the amplification factor, input resistance and output resistance of the two stage amplifier when opening the loop. Fill in table 3.4 4. according to the depth of negative feedback to estimate the negative feedback amplification circuit closed loop voltage amplification factor Auuf, fill in table 3.6, RW2, respectively, 1 K, 2, K omega. Four 、 experimental principle 1. multistage amplifier Amplification factor of a multistage amplifier However, attention should be paid to the multi-stage amplifier cascade, and the latter amplifier is the load of the front amplifier, and the input resistance at the back stage is considered as the pre stage load resistor. The input resistance of the multistage amplifier is the input resistance of the first stage amplifier, and the output resistance is the final stage output resistance. That is: 2. negative feedback amplifier 1) negative feedback type and decision According to the superposition of different ways and the input signal sampling mode output feedback signals of different negative feedback can be divided into four basic c