S 2011 Design and Experiment Project Lab 4 MOSFET

S 2011 Design and Experiment Project Lab 4 MOSFET - MOSFET...

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MOSFET Transistors EEE 3308C Spring 2011 1 EEE 3308C –Design and Experiment Project Lab #4A (Week 1) MOSFET Transistor and Amplifiers 1. Objectives The objective of this Design and Experiment Project is to gain a fundamental understanding of the MOSFET transistor and its application to single n-channel MOSFET amplifiers as well as the large-signal and small-signal operation of a CMOS inverter/amplifier. 2. Pre-lab I (to be done before labs of week 1) (1) Find and obtain a copy of the datasheet for a TI CD4007UBE CMOS Inverter. (2) Read Sections 5.1—5.3 on the Device Structure and Physical Operation, Current-Voltage Characteristics, and MOSFET Circuits at DC in Sedra and Smith. TO TURN IN TO YOUR TA ON A SEPARATE SHEET (No credit unless turned in.) (3) Is an ideal n-channel MOSFET (NMOS transistor) a symmetric device (if you switched the drain and source, would it work the same)? Why? (4) Sketch the I D –V DS characteristic for an NMOS transistor neglecting the bulk effect. Identify each region of operation and the constraints for each region. (5) Thought Question: If the source is grounded, but a negative voltage is applied to the body, would you expect the I-V characteristic to change? Why? (Note: This effect, known as the body effect (Chapter 5), has been discussed in lecture.) 3.1 MOSFET I-V Characteristics: 3.1.1 NMOS I-V characteristics Instructions : - Using LTSpice, place a NMOS with the source grounded and a DC source to the gate, and another DC to the drain. (use nmos4 model and tie body to source, right click on the model and insert W= 30u, L = 10u) Graph: - Use the nested DC sweep under the Simulation Command and plot the I-V characteristic of the MOS. Analysis: - Record four operating points (VGS, VDS) pairs where the transistor is active and in the saturation region, each operating point should have a different VGS. I D V GS V DS
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MOSFET Transistors EEE 3308C Spring 2011 2 - What you are effectively doing by connecting the body to the source in the above circuit? What if you connect the body to ground? - How can you determine the threshold voltage, V th ? Using the slope of the I D -V DS line in the saturation region, determine the value of lambda (λ) for each of the four operating points. (The TA will discuss the parameter λ and its relation to the slope of the I D -V DS line in the saturation region, 1/ ( ) 1/ / | GS GS o D D DS v V r I i v   ). (See also Chapter 5 on Finite Output Resistance in Saturation.) Also, calculate the output resistance from the above relation. - Extract the value of the transconductance g m from another slope, the slope of the I D -V GS curve defined as /| GS GS m D GS v V g i v   . 3.1.2 PMOS I-V characteristics Instructions - Using LTspice, repeat the same process for a PMOS. (use pmos4 model and tie body to source, right click on the model and insert W= 60u, L = 10u) Analysis: - Record four operating points (VGS, VDS) pairs where the transistor is active and in the saturation region, each operating point should have a different VGS.
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This note was uploaded on 07/28/2011 for the course EEL 3308C taught by Professor Yoon during the Spring '11 term at University of Florida.

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S 2011 Design and Experiment Project Lab 4 MOSFET - MOSFET...

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