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Premium member Presentation Transcript Chapter 2: FET Small-Signal Analysis: Chapter 2: FET Small-Signal Analysis Faculty of Electrical & Electronic Engineering, KUKTEMContents: Contents FET small signal model JFET bias configuration MOSFET small signal analysis E-MOSFET drain feedback and voltage-divider configuration FET amplifier networks designPowerPoint Presentation: Introduction FETs provide • excellent voltage gain • high input impedance • low-power consumption • good frequency range small in size and weightPowerPoint Presentation: FET Small-Signal Model Transconductance The relationship of VGS (input) to ID (output) is called transconductance. The transconductance is denoted gm . [Formula 9.2]PowerPoint Presentation: Graphical Determination of gmPowerPoint Presentation: Mathematical Definition of gm [Formula 9.2] [Formula 9.4] gm for VGS =0V: [Formula 9.5] [Formula 9.6] Effect of I D on g m for [Formula 9.8] [Formula 9.9]PowerPoint Presentation: FET Impedance Input Impedance Zi: [Formula 9.10] Output Impedance Zo: [Formula 9.11] [Formula 9.12] yos: admittance equivalent circuit parameter listed on FET specification sheets.PowerPoint Presentation: FET AC Equivalent CircuitPowerPoint Presentation: JFET Common-Source (CS) Fixed-Bias Configuration The input is on the gate and the output is on the drain.PowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.13] Output Impedance: [Formula 9.14] [Formula 9.15]PowerPoint Presentation: Voltage Gain [Formula 9.16] [Formula 9.17]PowerPoint Presentation: Phase Relationship A CS amplifier configuration has a 180-degree phase shift between input and output.PowerPoint Presentation: JFET CS Self-Bias Configuration This is a CS amplifier configuration therefore the input is on the gate and the output is on the drain.PowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.18] Output Impedance: [Formula 9.19] [Formula 9.20]PowerPoint Presentation: Voltage Gain [Formula 9.21] [Formula 9.22]PowerPoint Presentation: Phase Relationship A CS amplifier configuration has a 180-degree phase shift between input and output.PowerPoint Presentation: JFET CS Self-Bias Configuration – Unbypassed Rs If Cs is removed, it affects the gain of the circuit.PowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.23] Output Impedance: [Formula 9.25(b)]PowerPoint Presentation: Voltage Gain [Formula 9.26] [Formula 9.27]PowerPoint Presentation: JFET CS Voltage-Divider Configuration This is a CS amplifier configuration therefore the input is on the gate and the output is on the drain.PowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.28] Output Impedance: [Formula 9.29] [Formula 9.30]PowerPoint Presentation: Voltage Gain [Formula 9.31] [Formula 9.32]PowerPoint Presentation: JFET Source Follower (Common-Drain) Configuration In a CD amplifier configuration the input is on the gate, but the output is from the source.PowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.33] Output Impedance: [Formula 9.34] [Formula 9.35]PowerPoint Presentation: Voltage Gain [Formula 9.36] [Formula 9.37]PowerPoint Presentation: Phase Relationship A CD amplifier configuration has no phase shift between input and output.PowerPoint Presentation: JFET Common-Gate Configuration The input is on source and the output is on the drain.PowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.39] [Formula 9.40] Output Impedance: [Formula 9.41] [Formula 9.42]PowerPoint Presentation: Voltage Gain [Formula 9.43] [Formula 9.44]PowerPoint Presentation: Phase Relationship A CG amplifier configuration has no phase shift between input and output.PowerPoint Presentation: Depletion-Type MOSFETs D-MOSFETs have similar AC equivalent models. The only difference is that V SGQ can be positive for n-channel devices and negative for p-channel devices. This means that gm can be greater than gm0.PowerPoint Presentation: D-MOSFET AC Equivalent ModelPowerPoint Presentation: Enhancement-Type MOSFETs There are two types of E-MOSFETs: nMOS or n-channel MOSFETs pMOS or p-channel MOSFETsPowerPoint Presentation: E-MOSFET AC Equivalent Model gm and rd can be found in the specification sheet for the FET.PowerPoint Presentation: E-MOSFET CS Drain-Feedback ConfigurationPowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.46] [Formula 9.47] Output Impedance: [Formula 9.48] [Formula 9.49]PowerPoint Presentation: Voltage Gain [Formula 9.50] [Formula 9.51]PowerPoint Presentation: Phase Relationship This is a CS amplifier configuration therefore it has 180-degree phase shift between input and output.PowerPoint Presentation: E-MOSFET CS Voltage-Divider ConfigurationPowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.52] Output Impedance: [Formula 9.53] [Formula 9.54]PowerPoint Presentation: Voltage Gain [Formula 9.55] [Formula 9.56]PowerPoint Presentation: Summary TablePowerPoint Presentation: Summary TablePowerPoint Presentation: Troubleshooting 1. Check the DC bias voltages – if not correct check power supply, resistors, FET. Also check to ensure that the coupling capacitor between amplifier stages is OK. 2. Check the AC voltages – if not correct check FET, capacitors and the loading effect of the next stage.PowerPoint Presentation: Practical Applications • Three-Channel Audio Mixer • Silent Switching • Phase Shift Networks • Motion Detection System You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
Chapter2 msrit2011 Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 103 Category: Education License: Some Rights Reserved Like it (0) Dislike it (0) Added: November 27, 2011 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Chapter 2: FET Small-Signal Analysis: Chapter 2: FET Small-Signal Analysis Faculty of Electrical & Electronic Engineering, KUKTEMContents: Contents FET small signal model JFET bias configuration MOSFET small signal analysis E-MOSFET drain feedback and voltage-divider configuration FET amplifier networks designPowerPoint Presentation: Introduction FETs provide • excellent voltage gain • high input impedance • low-power consumption • good frequency range small in size and weightPowerPoint Presentation: FET Small-Signal Model Transconductance The relationship of VGS (input) to ID (output) is called transconductance. The transconductance is denoted gm . [Formula 9.2]PowerPoint Presentation: Graphical Determination of gmPowerPoint Presentation: Mathematical Definition of gm [Formula 9.2] [Formula 9.4] gm for VGS =0V: [Formula 9.5] [Formula 9.6] Effect of I D on g m for [Formula 9.8] [Formula 9.9]PowerPoint Presentation: FET Impedance Input Impedance Zi: [Formula 9.10] Output Impedance Zo: [Formula 9.11] [Formula 9.12] yos: admittance equivalent circuit parameter listed on FET specification sheets.PowerPoint Presentation: FET AC Equivalent CircuitPowerPoint Presentation: JFET Common-Source (CS) Fixed-Bias Configuration The input is on the gate and the output is on the drain.PowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.13] Output Impedance: [Formula 9.14] [Formula 9.15]PowerPoint Presentation: Voltage Gain [Formula 9.16] [Formula 9.17]PowerPoint Presentation: Phase Relationship A CS amplifier configuration has a 180-degree phase shift between input and output.PowerPoint Presentation: JFET CS Self-Bias Configuration This is a CS amplifier configuration therefore the input is on the gate and the output is on the drain.PowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.18] Output Impedance: [Formula 9.19] [Formula 9.20]PowerPoint Presentation: Voltage Gain [Formula 9.21] [Formula 9.22]PowerPoint Presentation: Phase Relationship A CS amplifier configuration has a 180-degree phase shift between input and output.PowerPoint Presentation: JFET CS Self-Bias Configuration – Unbypassed Rs If Cs is removed, it affects the gain of the circuit.PowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.23] Output Impedance: [Formula 9.25(b)]PowerPoint Presentation: Voltage Gain [Formula 9.26] [Formula 9.27]PowerPoint Presentation: JFET CS Voltage-Divider Configuration This is a CS amplifier configuration therefore the input is on the gate and the output is on the drain.PowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.28] Output Impedance: [Formula 9.29] [Formula 9.30]PowerPoint Presentation: Voltage Gain [Formula 9.31] [Formula 9.32]PowerPoint Presentation: JFET Source Follower (Common-Drain) Configuration In a CD amplifier configuration the input is on the gate, but the output is from the source.PowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.33] Output Impedance: [Formula 9.34] [Formula 9.35]PowerPoint Presentation: Voltage Gain [Formula 9.36] [Formula 9.37]PowerPoint Presentation: Phase Relationship A CD amplifier configuration has no phase shift between input and output.PowerPoint Presentation: JFET Common-Gate Configuration The input is on source and the output is on the drain.PowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.39] [Formula 9.40] Output Impedance: [Formula 9.41] [Formula 9.42]PowerPoint Presentation: Voltage Gain [Formula 9.43] [Formula 9.44]PowerPoint Presentation: Phase Relationship A CG amplifier configuration has no phase shift between input and output.PowerPoint Presentation: Depletion-Type MOSFETs D-MOSFETs have similar AC equivalent models. The only difference is that V SGQ can be positive for n-channel devices and negative for p-channel devices. This means that gm can be greater than gm0.PowerPoint Presentation: D-MOSFET AC Equivalent ModelPowerPoint Presentation: Enhancement-Type MOSFETs There are two types of E-MOSFETs: nMOS or n-channel MOSFETs pMOS or p-channel MOSFETsPowerPoint Presentation: E-MOSFET AC Equivalent Model gm and rd can be found in the specification sheet for the FET.PowerPoint Presentation: E-MOSFET CS Drain-Feedback ConfigurationPowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.46] [Formula 9.47] Output Impedance: [Formula 9.48] [Formula 9.49]PowerPoint Presentation: Voltage Gain [Formula 9.50] [Formula 9.51]PowerPoint Presentation: Phase Relationship This is a CS amplifier configuration therefore it has 180-degree phase shift between input and output.PowerPoint Presentation: E-MOSFET CS Voltage-Divider ConfigurationPowerPoint Presentation: AC Equivalent CircuitPowerPoint Presentation: Impedances Input Impedance: [Formula 9.52] Output Impedance: [Formula 9.53] [Formula 9.54]PowerPoint Presentation: Voltage Gain [Formula 9.55] [Formula 9.56]PowerPoint Presentation: Summary TablePowerPoint Presentation: Summary TablePowerPoint Presentation: Troubleshooting 1. Check the DC bias voltages – if not correct check power supply, resistors, FET. Also check to ensure that the coupling capacitor between amplifier stages is OK. 2. Check the AC voltages – if not correct check FET, capacitors and the loading effect of the next stage.PowerPoint Presentation: Practical Applications • Three-Channel Audio Mixer • Silent Switching • Phase Shift Networks • Motion Detection System