ENGR 311ENGR 311PSpice Simulation and Lab Instrumentation - Laboratory # 5MOSFET DevicesObjectives:This laboratory exercise will explore some of the characteristics of MOSFET devices. This will be doneby looking at the static and switching characteristics of a small power MOSFET.Pre-Laboratory1. Obtain the data sheet for the IRF720 from the International Rectifier website at www.irf.com.Review the plot in the data sheet (Fig. 1) of the static characteristics (ID vs. VDS) for the InternationalRectifier IRF720 at VGS = 4.5, 5, and 6v for VDS = 0-10v.2. Review the typical transfer characteristics of ID vs. VGS in Fig. 3 of the data sheet. Also take note ofthe plot in Figure 6 of the data sheet of VGS vs. QG. Remember that the gate must charge up before thechannel can be opened, and gate charge is related to gate current.3. For the circuit in Fig. 1 below with a ±6v, 100kHz pulsed source for VGG, use Pspice (use the modelfor the irf150) to obtain a transient simulation of the circuit for RG = 1kΩ and 500Ω. Plot VGS and VDSvs. time on one graph, and IG vs. time on a second graph. Be sure to include source resistances (of thefunction generator) in the simulations.4. If the input of the MOSFET is modeled as shown in Fig. 2, determine the equivalent inputcapacitance, Cgs, from the data generated in part 3. Hint: remember how a time constant is defined interms of a graph of the time response of a circuit to a step input.5. Calculate the value of RDS-ON (VDS/ID when the device is "on" in the ohmic region) from thesimulated data and compare it to the data sheet value. Hint: use Ohm’s law.Fig. 1 – MOSFET Pulse Test CircuitFig. 2 – MOSFET Input Equivalent CircuitLaboratory1 Assemble the circuit in Figure 1 with VGG a ±6v square wave and RG = 1kΩ. Make sketches of IG,VGS, and VDS vs. time. Sufficient data should be taken such that the maxima, minima, and rise time areavailable. VGS and VDS should be sketched on the same figure (use both oscilloscope channels) such thatthe voltages can be correlated for switching evaluation. Also, to view the IG waveform, you will need touse both channels of the oscilloscope and the "invert" and "add" functions.2 Experimentally determine the time constant for the VGS waveform. From this information,calculate an approximate value of input capacitance, Cgs. Compare this to the pre-lab and datasheet values.3. Repeat steps 1 and 2 with RG = 510Ω.4. From the VDS and ID waveforms, calculate the value of RDS-ON for your device. Compare thesewith the pre-lab and data sheet values.Report1. Make a table for the comparisons of RDS-ON and Cgs.2. Comment on any change in switching time resulting from a variation in RG. How well do themeasured waveforms compare with those obtained from the simulation?3. Comment on the overall quality of your
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