EE 2212

EXPERIMENT 6

4 November 2021

NOTEBOOK REVIEW

MOSFET I-V Characteristics

NOTEBOOK REVIEW:

We will use the first hour or so for individual reviews of your notebook; the remaining laboratory time will be for the MOSFET I-V characterizations.

Ø The intent is to model the notebook review as if we were having an industrial design review; that is a review that is constructive for every one concerned. Discussion is strongly encouraged. We are all in it together.

Ø In alphabetical order based upon my class list for each lab, I will ask to “see” your notebook. That is you will display selective pages of one or more of the five experiments to date. Be sure your imaging systems in whatever platform you are using IS OPERATIONAL!

Ø I will evaluate your work on a CHECK PLUS (Exceeds Expectations), CHECK (Meets expectations). CHECK MINUS (Does not meet expectations) rubric. The evaluations will be confidential.

Ø I anticipate each of the reviews will require only 2-3 minutes, consequently we should complete the review in an hour or so leaving two hours for the MOS Lab.

Ø I am using typical Intellectual Property guidelines acceptable in patent filings. I expect to see a Table of Contents, URL where your computer files are kept, dated entries for when the work was done, circuit diagrams, comments and conclusions, essentially following the guidelines in the LabInfo.docx LabInfo.docx document.

PURPOSE

To measure the I-V characteristics of an N-channel MOSFET on the CD 4007 array. Enter your data:

VGS, VDS, ID in an EXCEL spread sheet and use these data for preparing your graphs and parameterization of

the FET.

COMPONENTS

Ø CD4007 MOSFET array

PRELAB

Prepare a detailed circuit diagrams in your notebook of how you will connect an NMOS for measuring the I-V curves and how you will connect the inverter circuits. Study the material in Chapter 4. A complete manufacturer’s data sheet has been posted as a pdf file on the class WEB page.

The device you will use throughout this experiment and Experiment 7 is a CD4007B Transistor array. CD4007-tiDataSheet.pdf It contains three N-channel and three P-channel devices connected as shown Figure 6.1. Detailed schematic diagrams and pinouts are available on the data sheet and also given below,

Please use care when working with these chips. They are very susceptible to excessive voltage and ESD (Electro-Static Damage).Avoid handling by the pins. Remember to touch a black lead (ground) of one of the BNC cables connected to the oscilloscope or signal generator or the ground terminal on the power supply before you start wiring your circuit. This time of the year often has low relative humidities which make ESD more of an issue. Do not exceed the experiment settings in an attempt to make your experiment work. The pin configuration is given in Figure 6.1. Note that you will be using the CD4007B which have a lower maximum voltage rating than the CD4007UB. The diagrams are the same for both the “B” and “UB” suffix devices. Study the I-V curves, Figure 5, provided in the data sheets CD4007-tiDataSheet.pdf so that you have some idea of what to expect. Also study the chip circuit diagram. You should be able to identify the operation and function of all of the individual devices. Observe the input protection circuitry, D1 and D2, that we discussed in class.

Figure 6.1 Pin Configuration of CD4007.

Warning: Pin 14 should always be connected to the most positive dc voltage in the circuit. Pin 7 will always be connected to the most negative dc voltage in the circuit

(or else )!!!

PROCEDURE

I-V Characteristic of an N-channel MOSFET

Ø Connect the circuit shown in Figure 6.2. Use the NMOS connected to pins 6 (GATE), 7 (SOURCE), and 8 (DRAIN). Remember to also connect pin 14 also to the +VDD supply. Pin 7 is shown connected to ground, VSS = 0. Although you can use the built-in mA meter on the power supply to measure I_D , a better way yielding better accuracy is to measure current by measuring the voltage drop across a 1000 Ω resistor connected from Pin 8 to Pin 14 and realizing that I_D = V_{(across the resistor})/1000Ω.

Ø Do not use the digital multimeter to measure current because of the hassle in replacing the internal fuse. Use the voltage readout on the power supply as you sweep V_DD from 0 to 15 volts for each value of VGS from 0 to 6 volts in 1-volt increments. Measure VDS and ID for each value of VGS using the multimeter. Note that the threshold voltage, V_T , is in the 1 to 2 volt range. Refer to the data sheets where similar curves are illustrated. Record data in an EXCEL spread sheet.

Ø

Figure 6.2 I_D-V_DS As A Function of V_GS Characteristic Measurement For an NMOS

Ø Note that you should keep below I_D = 10mA; since this is the maximum rated value for this chip, consequently you may not be able to use all values of V_GS depending upon your chip. Plot VDS and ID data as you proceed. Record data in an EXCEL spread sheet. Using an EXCEL spread sheet and extracting graphs from the spread sheet is a good way to display and understand the data.

Ø The CD 4007, as are most MOS ICs, is unforgiving for ESD and over voltage and over current.

Ø Plot your data and use a linear regression (least squares fit) to extract values for VTO, LAMBDA, k, and KP and develop a SPICE model that compares with your measured curves. An EXCEL spread sheet works well and yields nice graphs. The objective is to obtain I_D versus V_DS for several different values of V_GS. Look at Figures 5 and 8 on the CD 4007 data sheet as a guide as to what to expect. You will have to assume W/L=1 because you do not know the actual values of W and L and then adjust KP accordingly. This model development from your parameter extractions should be included in your report. Develop a Shichman-Hodges model equation for your NMOS.

Ø Observe that SPICE syntax for K_n^’ (for an NMOS) and K_p^’ (for a PMOS) is KP, independent whether you are modeling an NMOS or PMOS. Refer to Table 4.2 from the text.

A holdover from our LED discussions

Now to assist with your mathematics and physics:

How I feel about WINDOWS 10 on my DELL computer. And now WINDOWS 11!!!