实验三 多级放大器与负反馈放大器（The three - stage amplifier and the negative feedback amplifier）.doc

实验三 多级放大器与负反馈放大器（The three - stage amplifier and the negative feedback amplifier） The three - stage amplifier and the negative feedback amplifier I. experimental purpose 1. Master the relationship between amplification multiples of multistage amplifiers and magnification at all levels 2. Learn how to introduce negative feedback in the amplifier circuit The effect of negative feedback on the dynamic characteristics of the amplifier was controlled by the experimental test 2. Experimental instruments and devices Experimental apparatus Dc stabilizer power supply, function generator, digital oscilloscope, multimeter 2. Experimental devices Table 3.1 experimental devices Iii. Preliminary requirements 1. Review the content of multistage amplifier and negative feedback amplifier in the textbook. 2. Suppose to adjusting experiment RW1 ICQ1 = 1.0 mA, estimate circuit diagram 1 amplifier quiescent point data (beta material 200, RBB material 300 Ω, UBE material fill in the table 3.2 0.7 V). 3. Calculate the magnification, input resistance and output resistance of the two-stage amplifying circuit in the opening ring 4. According to the depth of the negative feedback to estimate the closed-loop voltage negative feedback amplifier circuit magnification Auuf, fill in the table 3.6, RW2 Ω respectively take 1 k, 2 k Ω. 4. Experimental principle 1. Multistage amplifier Amplification of multistage amplifiers But to pay attention to the multistage amplifier cascade, the rear amplifier is the load of the former amplifier, and the input resistance of the rear stage is considered as the front load resistor. The input resistance of a multistage amplifier is the input resistance of the first stage amplifier, and the output resistor is the final output resistor. That is: 2. Negative feedback amplifier 1) negative feedback type and judgment According to the feedback signal output end of the different methods of sampling and the input signal superposition methods: negative feedback can be divid