EE203-SUNYBuffalo-34-Chapter05-02

EE203-SUNYBuffalo-34-Chapter05-02 - SMALL for Big Things...

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Unformatted text preview: SMALL for Big Things University at Buffalo SMALL for Big Things University at Buffalo nanobioSensors & MicroActuators Learning Lab The State University of New York nanobioSensors & MicroActuators Learning Lab The State University of New York EE 203 Circuit Analysis 2 Lecture 34 Chapter 5.2 Terminal Voltages, Currents Currents (continue) Kwang W. Oh, Ph.D., Assistant Professor SMALL (nanobioSensors and MicroActuators Learning Lab) Department of Electrical Engineering University at Buffalo, The State University of New York 215E Bonner Hall, SUNY-Buffalo, Buffalo, NY 14260-1920 Tel: (716) 645-3115 Ext. 1149, Fax: (716) 645-3656 E-mail: kwangoh@buffalo.edu, http://www.SMALL.Buffalo.edu EE 203 Circuit Analysis 2 | Spring 2008 | Prof. Kwang W. Oh | EE@SUNY-Buffalo Lecture 34 | Chapter 5 | 2/4 | 1/10 Example 5.1 (1) vb = 0 = v p ( = vn ) i25 + i100 = in ( = 0) va − vn vo − vn + = in 25000 100000 1 − 0 4 vo − 0 ×+ =0 25000 4 100000 4 + vo = 0 Negative feedback path from the op amp amp’s output to its inverting input through the 100 kΩ resistor let’s assume the op amp is confined to to its linear operating region ∴ −10 V ≤ ( vo = −4 V) ≤ 10 V EE 203 Circuit Analysis 2 | Spring 2008 | Prof. Kwang W. Oh | EE@SUNY-Buffalo Lecture 34 | Chapter 5 | 2/4 | 2/10 SMALL for Big Things University at Buffalo SMALL for Big Things University at Buffalo nanobioSensors & MicroActuators Learning Lab The State University of New York nanobioSensors & MicroActuators Learning Lab The State University of New York Example 5.1 (2) Example 5.1 (3) vb = 2 V = v p ( = vn ) vb = v p = vn i25 + i100 = in ( = 0) i25 + i100 = in ( = 0) va − vn vo − vn + = in 25000 100000 1 − 2 4 vo − 2 ×+ =0 25000 4 100000 − 4 + vo − 2 = 0 va − vn vo − vn + = in 25000 100000 1.5 − vb 4 vo − vb ×+ =0 25000 4 100000 6 − 4vb + vo − vb = 0 ∴ −10 V ≤ ( vo = 6 V) ≤ 10 V EE 203 Circuit Analysis 2 | Spring 2008 | Prof. Kwang W. Oh | EE@SUNY-Buffalo 1 vb = (6 + vo ) 5 Lecture 34 | Chapter 5 | 2/4 | 3/10 − 10 V ≤ vo ≤ 10 V 10 10 − 4 V ≤ (6 + vo ) ≤ 16 V − 4 1 16 V ≤ ( vb = (6 + vo )) ≤ V 5 5 5 − 0.8V ≤ vb ≤ 3.2 V EE 203 Circuit Analysis 2 | Spring 2008 | Prof. Kwang W. Oh | EE@SUNY-Buffalo Lecture 34 | Chapter 5 | 2/4 | 4/10 SMALL for Big Things University at Buffalo SMALL for Big Things University at Buffalo nanobioSensors & MicroActuators Learning Lab The State University of New York nanobioSensors & MicroActuators Learning Lab The State University of New York Inverting-Amplifier Circuit (1) EE 203 Circuit Analysis 2 Lecture 34 Chapter 5.3 Inverting-Amplifier Circuit Kwang W. Oh, Ph.D., Assistant Professor SMALL (nanobioSensors and MicroActuators Learning Lab) Department of Electrical Engineering University at Buffalo, The State University of New York 215E Bonner Hall, SUNY-Buffalo, Buffalo, NY 14260-1920 Tel: (716) 645-3115 Ext. 1149, Fax: (716) 645-3656 E-mail: kwangoh@buffalo.edu, http://www.SMALL.Buffalo.edu EE 203 Circuit Analysis 2 | Spring 2008 | Prof. Kwang W. Oh | EE@SUNY-Buffalo Lecture 34 | Chapter 5 | 2/4 | 5/10 Assumption OP Amp is operating in its linear region OP Amp is ideal Components & Parameters Two resistances: Rf, Rs A voltage siignal source: vs A short circuit (vp = 0): between the noninverting input terminal (+) and the common node The output voltage is an inverted, scaled replica of the input replica Sign reversal from input to output Scaling factor, or gain A, = the ratio of Rf/Rs is + i f = in vs − vn vo − vn + = in Rs Rf vs − 0 vo − 0 + =0 Rs Rf EE 203 Circuit Analysis 2 | Spring 2008 | Prof. Kwang W. Oh | EE@SUNY-Buffalo ∴ vo = − Rf Rs vs Lecture 34 | Chapter 5 | 2/4 | 6/10 SMALL for Big Things University at Buffalo SMALL for Big Things University at Buffalo nanobioSensors & MicroActuators Learning Lab The State University of New York nanobioSensors & MicroActuators Learning Lab The State University of New York Inverting-Amplifier Circuit (2) Open-Loop Ideal OP Amp Gain A = infinite However, the upper limit on the gain (Rf /Rs) is determined by the power supply voltages and the value of the signal voltage vs if V+ = V – = VCC Open Open-loop operation No negative feedback path The value of A is often called the open-loop gain of the OP Amp OP in≈ 0 VRs= inRs≈0 vn≈vs we get For example VCC = 15 V and vs= 10 mV A = Rf /Rs < |15 V / 10 mV|= 1500 EE 203 Circuit Analysis 2 | Spring 2008 | Prof. Kwang W. Oh | EE@SUNY-Buffalo Lecture 34 | Chapter 5 | 2/4 | 7/10 EE 203 Circuit Analysis 2 | Spring 2008 | Prof. Kwang W. Oh | EE@SUNY-Buffalo Lecture 34 | Chapter 5 | 2/4 | 8/10 SMALL for Big Things University at Buffalo SMALL for Big Things University at Buffalo nanobioSensors & MicroActuators Learning Lab The State University of New York nanobioSensors & MicroActuators Learning Lab The State University of New York Summing-Amplifier Circuit EE 203 Circuit Analysis 2 Lecture 34 Chapter 5.4 Summing-Amplifier Circuit Kwang W. Oh, Ph.D., Assistant Professor SMALL (nanobioSensors and MicroActuators Learning Lab) Department of Electrical Engineering University at Buffalo, The State University of New York 215E Bonner Hall, SUNY-Buffalo, Buffalo, NY 14260-1920 Tel: (716) 645-3115 Ext. 1149, Fax: (716) 645-3656 E-mail: kwangoh@buffalo.edu, http://www.SMALL.Buffalo.edu ia + ib + ic + i f = in va − vn vb − vn vc − vn vo − vn + + + = in Ra Rb Rc Rf va − 0 vb − 0 vc − 0 vo − 0 + + + =0 Ra Rb Rc Rf ∴ vo = −( Rf Ra va + Rf Rb vb + Rf Rc vc ) If Ra = Rb = Rc = Rs Then, vo = − Rf Rs ( va + vb + vc ) If we make Rs = R f Then, vo = −( va + vb + vc ) EE 203 Circuit Analysis 2 | Spring 2008 | Prof. Kwang W. Oh | EE@SUNY-Buffalo Lecture 34 | Chapter 5 | 2/4 | 9/10 EE 203 Circuit Analysis 2 | Spring 2008 | Prof. Kwang W. Oh | EE@SUNY-Buffalo Lecture 34 | Chapter 5 | 2/4 | 10/10 ...
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This note was uploaded on 10/19/2011 for the course EE 203 taught by Professor Staff during the Spring '08 term at SUNY Buffalo.

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