EE 2212

EXPERIMENT 6

11 March 2021

MOSFET I-V Characteristics

PURPOSE

To measure the V_T and k on an N-channel MOSFET on the CD 4007 NMOS array.

COMPONENTS

Ø CD4007 MOSFET array

Ø Two 9-Volt Battery Supplies

Ø 10KΩ or 100KΩ Potentiometer

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 CD4007-tiDataSheet.pdf.

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 on Wednesday, 21 October

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 = 9 volt battery

Figure 6.2 Circuit Used To Extract VT and k.

· You will be using the HANTEK DMM to measure VGS and ID for each data set.

· You will be able to adjust VGS from 0 to +6 volts by using the 10K or 100K potentiometer

· You will have to switch the DMM Red and Black test leads from setting and measuring VGS and measuring ID between the Voltage Input and the mA current input.

· VDS is essentially a constant at +9 volts.

· Verify that Pin 14 is connected to +9 volts as shown in Figure 6.2

· Use the DMM to verify the potentiometer value you are using.

Ø Adjust and measure VGS from 0 to 6 volts in 1-volt increments and for each VGS, switch the red lead from the VGS measurement to the mA input and measure ID. You could use 0.5 volt VGS steps between VGS = 3 and 6 volts to improve accuracy. Because the potentiometer is hard to adjust to exact values, you should use whatever makes sense.

Ø Record VGS and ID to an EXCEL spread sheet. Graph SQRT(ID) versus VGS and extract values for VT and k.

Ø Build a SPICE model using your values of VT (VTO) and k where KP in SPICE is =2xk. Refer to 19 and 21 October Class Notes.

A holdover from our LED discussions

Now to assist with your mathematics and physics:

How I feel about WINDOWS 10 on my DELL computer.