电子电路基本演示课件CH7.pptVIP

Ch7 Operational Amplifiers and Op Amp Circuits 7.1 Operational Amplifiers 7.2 Op Amp Circuits 7.3 Active Filter 7.4 Op Amp Positive Feedback Circuits and Analog Electronics Readings: Gao-Ch7, Ch9; Floyd-Ch6 Ch7 Operational Amplifiers and Op Amp Circuits 7.1 Operational Amplifiers Key Words: Op Amp Model Ideal Op Amp Op Amp transfer characteristic Feedback Virtual short Ch7 Operational Amplifiers and Op Amp Circuits 7.1 Operational Amplifiers (Op Amp ) Inverting input At a minimum, op amps have 3 terminals: 2 input and 1 output. An op amp also requires dc power to operate. Often, the op amp requires both positive and negative voltage supplies (V+ and V-). Ch7 Operational Amplifiers and Op Amp Circuits 7.1 Operational Amplifiers Symbol One of the input terminals (1) is called an inverting input terminal denoted by ‘-’ The other input terminal (2) is called a non-inverting input terminal denoted by ‘+’ Ch7 Operational Amplifiers and Op Amp Circuits 7.1 Operational Amplifiers The Op Amp Model The op amp is designed to sense the difference between the voltage signals applied to the two input terminals and then multiply it by some gain factor A such that the voltage at the output terminal is A(v+-v-). The voltage gain A is very large (practically infinite). The gain A is often referred to as the differential gain or open-loop gain. The input resistance Rin is very large (practically infinite). The output resistance Ro is very small (practically zero). Ch7 Operational Amplifiers and Op Amp Circuits 7.1 Operational Amplifiers Ideal Op Amp Ch7 Operational Amplifiers and Op Amp Circuits 7.1 Operational Amplifiers For A741, A=100dB=105， if vo=10V， Ch7 Operational Amplifiers and Op Amp Circuits 7.1 Operational Amplifiers Op Amp transfer characteristic curve Ch7 Operational Amplifiers and Op Amp Circuits 7.1 Operational Amplifiers Op Amp transfer characteristic curve So far, we have been looking at t