III. Pre-Laboratory ExercisesEE 462G Laboratory # 3Diode Clipping CircuitsbyDrs. A.V. Radun and K.D. Donohue (9/20/06)Department of Electrical and Computer EngineeringUniversity of KentuckyLexington, KY 40506(Lab 2 – Report due at beginning of lab period) (Pre-lab 3 and Lab-3 Datasheet due at the end of the lab period).I. Instructional Objectives- Design and implement clipping circuits based on the attributes of semiconductor diodes.See Horenstein 4.1 and 4.2II. Transfer CharacteristicsThis lab introduces diode circuits that alter input waveform shapes (wave shaping) and the graphical modeling of their transfer characteristics. Clipping circuits are used to restrict an output voltage to a particular range of values. The output voltage will be proportional to the inputvoltage as long as the input voltage lies within the desired range. Outside this range the output is clipped (held) to a constant value until the input falls within the “linear” range, where the output follows the input. The nonlinear switch-like properties of the diode can be used to implement this function. Clipping circuits are used in signal processing applications, radio modulation systems, and power supplies.III. Pre-Laboratory Exercises Transfer Characteristic of Diode1) Use data from the previous lab (Lab 2), and plot the following on the same graph (use different line styles to distinguish the plots):a. The measured I-V curve obtained with the curve tracerb. The result of the Shockley diode equation with the best-fit parameters. (Note the diode current can get very large from this equation and cause the vertical axis to get so large that it obscures the curve tracer data plot. Do not let this happen. Limit the range of the values evaluated on the Shockley equation to those of the curve tracer data so differences between the model and measured data in the critical regions can be seen clearly).c. A vertical line at the forward bias voltage value that was estimated in the last lab.This plot can be used for discussing observed results between the predicted and measuredresults of the clipping circuit. Make sure the axes of the plot are properly labeled.Vs10 k-V1Clipped Sine Wave Generation2) (a) Sketch the output waveforms for circuits in Fig. 1a, b, and c for a 250Hz input sine wave of amplitude 2.8 Vrms. Let DC sources V1 and V2 both equal to 1.2 V, and assume ideal diodes with a forward bias offset voltage that was estimated in the previous lab.(b) For the circuits of Parts (a) draw the transfer characteristic (Vout versus Vs) for Vs ranging between -5V and +5V.3) For the same source as described in the previous problem, use SPICE to graph the output of the circuit in Fig.1c for several periods where V1=V2= 1.2 V. Use SPICE to obtain the transfer characteristic of the circuit in Fig. 1c for Vs between -5V and +5V.4) The circuit in Fig. 1b is modified to result in the circuit in Fig. 1d. Describe how the measured output may change as a result of this modification.Power Distribution5) (a) Determine the average power delivered by the source in Fig. 1a (assume Vs is a 250Hzinput sine wave at 2.8 Vrms). Determine the average power absorbed by the diode and resistor. (b) Repeat Part (a) with the circuit having a 5.1k--load resistor (find the power absorbed in this resistor also).(a)(b)(c)(d)Figure 1. Circuits for analysis and experiment. Vs10 k-+Vout- Vs10 k-+Vout-V1 Vs10 k-+Vout-V1+Vout-V2Vs10 k-V1IV. Laboratory Procedure1. Generate Clipped Sine Wave: Assemble clipping circuits of Fig. 1a, b, and c with no load. Connect a 250Hz, 2.8Vrms sine wave signal from the function generator for the input Vs and use the power supply to make V1 and V2 equal to 1.2 volts. Beware of polarity and ground issues when using the power supply. Be sure the scope is in the Y-T mode (this is set using the scope’s display menu, and Y-T is typically the default mode). This mode displays the signals on Channel 1 and Channel 2 versus time. Vs and Vout should be displayed simultaneously. Record output waveforms for each circuit (sketch on datasheet and save images/data for presenting in lab report). Vary the voltages for V1 and V2 in order to determine their effect on the output. Describe qualitatively (in words) how V1 and V2 affect the output waveform (put this description in your datasheet). (Discussion Section: Comment on the observed output waveform for each circuit. Provide reasons for the particular results based on your diode models and data. Compare it to your pre–lab predictions. Describe the effect of V1 and V2 on the output waveform for the circuit of Fig 1c. and explain why the results appear as theydo based on the diode models and data.) Grounding issues with the power supply should be described in the procedure section.2. Measure Transfer Characteristics of Circuits: Assemble clipping circuits of Fig. 1a, b, and c as in Procedure 1. Change the scope to the X-Y mode (see display menu). Use the scope to display Vout versus Vs (Vout on the Y-axis). Adjust the function generator’s amplitude to set Vs to a 10 Vp-p sine wave that ranges from –5V to 5V. Record the trace for each circuit. Vary the frequency of the input waveform to determine its effect on the TC. In words and sketches (if necessary) on the data sheet briefly describe these effects. (Discussion: Summarize how changing frequency of input affects the TC curve and explain why these changes (if any) occur.)3. Generate Clipped Sine Wave with Load and Compare Power Distribution: Apply a 5.1k--load to the output of the circuit in Fig. 1a, and record the resulting waveform for Vs equal to a 2.8Vrms 250Hz sine wave. The digital multimeter and oscilloscope can be used to measure rms current and voltages in each circuit branch so average power can be computed (Recall: irms*vrms = Pav and v2rms / R = Pav). Measure the power delivered by the source, and power absorbed in the resistors and diode. Take the load resistor out and repeat power measurements. (Discussion: Described the change of power distribution as a result of the load. Compare to pre-lab results).4. Demonstrate Effects of Series Power Supply Placement: Compare the clipped sine wave outputs for the circuits of Figs. 1b and d by viewing input and output sine wave as done in Procedure 1. Vary the frequency of the sine wave input to find frequencies wherea phase difference between input and output waveform can be easily observed. Record the input and output waveforms for