ECEN 215, Principles of Electrical EngineeringDr. Mina RahimianLecture# 19 Date:10/30/13First order RC high pass filtersBand pass filterIn some applications it is desired to select a certain range of frequencies and discard the other frequencies. Such filters are useful in radio receivers for example.This filter is called band pass filter and can be made using RLC circuit. (second order circuits)Band stop filter (notch filter)In some applications it is desired to discard a certain range of frequencies and pass the other frequencies. This filter is called band stop filter and can be made using RLC circuit. (second order circuits)Ideal filtersAn ideal filter passes the components in the desired range with no change of amplitude or phase and totally rejects the undesired frequencies.Chaper 14, Operational Amplifierpin configurationA typical Op amp PackageAn operational amplifier (op amp) is an electronic circuit that contains many electronic devices such as transistors and diodes. The delailed analysis of op amp requires an understanding of electronic devices which is beyond the scope of this course. However, it can be used as a circuit building block by focusing on its terminal behavior.The operational amplifier came into existance as a basic building block for analog computers. it was referred to as operational because it was used to implement the mathematical operations such as addition, sign changing, comparing, intergation and differentiation.circuit symbolterminal voltage connectionThe equivalent circuit for non-ideal op ampvoltage transfer characteristicswithout a feedback connection, op amp can operate in three modes:In most practical applications, the output voltage of the op amp is fed beck to the inverting input. This is called a negative feedback.When a negative feed back is provided, the ratio of the output to the input voltage is called the closed loop gain which is insensitive to the open loop gain A.Ex. An op amp has an open loop gain of 2*105 Ω, input resistance of 2MΩ and output resistance of 50 Ω. Find the closed loop gain vo /vi and current i, when the op amp is connected as shown.Ideal op ampEx. Repeat the previous problem using ideal op amp
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