The main contents of the chapter consist of the following: MOSFET circuits at DC, MOSFET as an amplifier and as a switch, large –signal operation-the transfer characteristic, graphical derivation of the transfer characteristic, operation as a linear amplifier, operation as a switch. | Dr. Nasim Zafar Electronics 1 - EEE 231 Fall Semester – 2012 COMSATS Institute of Information Technology Virtual campus Islamabad DC Analysis of MOSFET and MOSFET as an Amplifier Lecture No. 30 Contents: MOSFET Circuits at DC MOSFET as an Amplifier and as a Switch Large –Signal Operation-The Transfer Characteristic Graphical Derivation of the Transfer Characteristic Operation as a Linear Amplifier Operation as a Switch 2 Dr. Nasim Zafar Lecture No. 30 DC Analysis of MOSFET Reference: Chapter Microelectronic Circuits Adel S. Sedra and Kenneth C. Smith. 3 Dr. Nasim Zafar MOSFET Circuit at DC Assuming device operates in saturation thus iD satisfies with iD~vGS equation. According to biasing method, write voltage loop equation. Combining above two equations and solve these equations. Usually we can get two value of vGS, only the one of two has physical meaning. 4 Dr. Nasim Zafar Dr. Nasim Zafar 5 MOSFET Circuit at DC 5. Checking the value of vDS if vDS≥vGS-Vt, the assuming is correct. if vDS≤vGS-Vt, the assuming is not correct. We shall use triode region equation to solve the problem again. The NMOS transistor is operating in the saturation region due to Example : of DC Analysis 6 Dr. Nasim Zafar DC Analysis of MOSFET Example Dr. Nasim Zafar 7 DC Analysis of MOSFET Example Dr. Nasim Zafar 8 Assuming the MOSFET operates in the saturation region Checking the validity of the assumption If not valid, solve the problem again for triode region Example : of DC Analysis 9 Dr. Nasim Zafar Example : of DC Analysis Dr. Nasim Zafar 10 Example : of DC Analysis Dr. Nasim Zafar 11 Example : of DC Analysis Dr. Nasim Zafar 12 Example : of DC Analysis Dr. Nasim Zafar 13 Example : of DC Analysis Dr. Nasim Zafar 14 Dr. Nasim Zafar 15 Lecture No. 30 MOSFET as an Amplifier and as a Switch Reference: Chapter Microelectronic Circuits Adel S. Sedra and Kenneth C. Smith. 16 Dr. Nasim Zafar MOSFET as an Amplifier Introduction In this lecture | Dr. Nasim Zafar Electronics 1 - EEE 231 Fall Semester – 2012 COMSATS Institute of Information Technology Virtual campus Islamabad DC Analysis of MOSFET and MOSFET as an Amplifier Lecture No. 30 Contents: MOSFET Circuits at DC MOSFET as an Amplifier and as a Switch Large –Signal Operation-The Transfer Characteristic Graphical Derivation of the Transfer Characteristic Operation as a Linear Amplifier Operation as a Switch 2 Dr. Nasim Zafar Lecture No. 30 DC Analysis of MOSFET Reference: Chapter Microelectronic Circuits Adel S. Sedra and Kenneth C. Smith. 3 Dr. Nasim Zafar MOSFET Circuit at DC Assuming device operates in saturation thus iD satisfies with iD~vGS equation. According to biasing method, write voltage loop equation. Combining above two equations and solve these equations. Usually we can get two value of vGS, only the one of two has physical meaning. 4 Dr. Nasim Zafar Dr. Nasim Zafar 5 MOSFET Circuit at DC 5. Checking the value of vDS if vDS≥vGS-Vt, the assuming
