BTEC HNC - Electronics - Investigate Circuits With Feedback

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<p>Investigate Circuits with FeedbackElectronics By Brendan Burr</p> <p>Brendan Burr BTEC Higher National Certificate in ElectronicsInvestigate Circuits with Feedback</p> <p>Table of ContentsTABLE OF CONTENTS...........................................................2 TASK 1 ...............................................................................5 1.1. Derive from first principles an expression for the closed loop voltage gain of a F/B amplifier......................................5 Solution:-.........................................................................................5 TASK 2................................................................................6 2.1 Describe the following types of negative feedback : .......6 Voltage ..............................................................................6 Solution:-.........................................................................................6 Current ..............................................................................6 Solution:-.........................................................................................6 Shunt ................................................................................7 Solution:-.........................................................................................7 Series ................................................................................7 Solution:-.........................................................................................7 2.2 Summarize the effects of the above types on circuit performance in the form of a table.......................................8 Solution:-.........................................................................................8 TASK 3 ...............................................................................9 3.1. Design only 1 of the following types of amplifier circuits, that uses negative feedback:-..............................................9 (a) Operational Amplifier OR (b) Emitter Follower................9 Solution:-.........................................................................................9 3.2 Produce a circuit diagram of the resultant design showing all component values...........................................................9 Solution:-.........................................................................................9 3.3 Use a 1 kHz input sine wave signal of amplitude 5 V peak to peak. to test your design using Croc Clips or MultiSim.......9 Solution:-.........................................................................................9 3.4 Record the results of the simulation in the form of input and output waveforms.........................................................9 Solution:-.........................................................................................9 2</p> <p>Brendan Burr BTEC Higher National Certificate in ElectronicsInvestigate Circuits with Feedback</p> <p>TASK 4..............................................................................10 4.1 Use Croc Clips or MultiSim to simulate a single stage circuit. Investigate the effect of applying feedback in terms of performance of the Voltage Gain of a Non Inverting Operational Amplifier circuit in the following 2 configurations:-.................................................................10 (a) Open Loop ...............................................................10 Solution:-.......................................................................................10 (b) Closed Loop ................................................................10 Solution:-.......................................................................................10 4.2 Record your results in the form of :-.............................10 (a) Circuit diagrams .......................................................10 Solution:-.......................................................................................10 (b) Voltage waveforms ......................................................11 Solution:-.......................................................................................11 (c) Table of input v output voltage levels............................12 Solution:-.......................................................................................12 (d) Table of Voltage gains..................................................12 Solution:-.......................................................................................12 4.3 Use Croc Clips or MultiSim to simulate a multi stage circuit...............................................................................13 Investigate the effects of applying feedback in terms of performance of the Input Resistance of a Unit Gain Voltage Follower (first stage) connected to an Inverting Operational Amplifier circuit (second stage) in the following 2 configurations :.................................................................13 (a) Open Loop ...............................................................13 Solution:-.......................................................................................13 (b) Closed Loop ................................................................13 Solution:-.......................................................................................13 4.4 Record your results in the form of :-.............................13 (a) Circuit diagrams ..........................................................13 Solution:-.......................................................................................13 (b) Voltage waveforms.......................................................14 Solution:-.......................................................................................14 (c) Table of input voltage v current ...................................16 Solution:-.......................................................................................16 3</p> <p>Brendan Burr BTEC Higher National Certificate in ElectronicsInvestigate Circuits with Feedback</p> <p>(d) Table of input resistance values....................................16 Solution:-.......................................................................................16 EVALUATION.....................................................................17 CONCLUSION.....................................................................17 APPENDIX 1......................................................................18 APPENDIX 2......................................................................19 APPENDIX 3......................................................................20 APPENDIX 4......................................................................21 APPENDIX 5......................................................................22 Books...............................................................................23 Catalogues........................................................................23 Websites...........................................................................23</p> <p>4</p> <p>Brendan Burr BTEC Higher National Certificate in ElectronicsInvestigate Circuits with Feedback</p> <p>Task 11.1. Derive from first principles an expression for the closed loop voltage gain of a F/B amplifier. (You must Include a block diagram as well as showing all calculations) Solution:-</p> <p>Derivation of Expression V f = VO Starting Point The total input voltage at the terminals of the amplifier is given by: Vi V f Vi VO But: VO = (Vi VO ) AV VO = Vi AV VO AV VO AV VO = Vi AV VO (1 AV ) = AV ViVO AV = Vi 1 AV </p>