- Parts 7 And 8 Parts 7 And 8 1 (94.19 KiB) Viewed 36 times
- Parts 7 And 8 Parts 7 And 8 2 (104.05 KiB) Viewed 36 times
- Parts 7 And 8 Parts 7 And 8 3 (41.91 KiB) Viewed 36 times
Basic operational amplifier circuits for inverting and non-inverting amplifiers are shown in Figures 1 and 2 respectively. These circuits will be constructed using a 741 (or a similar type operational amplifier) and + 10-V power supplies. RA VNI R RAVN2 RB is2 R in2 VPI Vouni VouT2 VP2 Vsi + Voll - A1 Vout2 A2 V1 V2 inl Figure 1. Non-Inverting Amplifier Figure 2. Inverting Amplifier = Vs Preliminary Calculations For the hand calculations, assume that the operational amplifier is ideal unless otherwise instructed. Vout! DV Step 1. For the circuit of Figure 1, write an expression for the voltage gain in terms of RA and Rg. Select a standard resistor value for R, such that 3.3k12 SR, 515k12 and select R, such that the gain calculated from the standard resistor values is given by A1 = 3 +10% (your instructor may assign a different gain value). Record the voltage gain calculated from the selected standard resistor values to two significant figures. Step 2. What is the input resistance Rel of the circuit of Figure 1? Which property of an ideal operational amplifier supports your conclusion? Using that same property, what fraction of the voltage at Vouti appears at Vni? Step 3. For the circuit of Figure 2, write an expression for the voltage gain 4,2 in terms of R V Vout2 1,2 and Rg. Using the same values for R, and R, as in Step 1, calculate the nominal voltage gain 42 from the standard resistor values to two significant figures.
Your 2 Step 3. For the circuit of Figure 2, write an expression for the voltage gain 4,2 in terms of RA and Rg. Using the same values for R, and R, as in Step 1, calculate the nominal voltage gain A2 from the standard resistor values to two significant figures. V 2 Step 4. Calculate the input resistance Rm2 for the circuit of Figure 2. SPICE Simulations Step 5. Enter the circuit of Figure 1 into SPICE. Use the resistor values determined in Step 1, and + 10-V power supplies. For the operational amplifier, use a SPICE model for a 741 unless you are directed by your instructor to use another type. Perform a DC sweep simulation in which vs, is swept over -5v +5v the entire power supply range from -JOU to the Obtain a plot of Vyı and Vouri as functions of Vst. The maximum value of Vouti should occur when it is as far positive as it can go, and in that case the output is said to be saturated. When saturated, the op-amp output does not change in response to changes in its input. Call the output value corresponding to positive saturation VouT max · Likewise, the most negative output value is called VOUT min · Identify VOUT max and VouT min on the plot. In the range for which amplifier is not saturated and is functioning as a linear amplifier, determine the slope of the transfer characteristic , and compare it with the calculated value of 4,1 Δνς Step 6. Repeat the simulation of Step 5 for the circuit of Figure 2. Obtain a plot of Vn2 and VouT2 as functions of Vsz. Identify VOUT max and VOUT min on the plot. In the amplifier's linear range, determine Δνουπι A2
SI Step 6. Repeat the simulation of Step 5 for the circuit of Figure 2. Obtain a plot of Vn2 and Vout2 as functions of Vsz. Identify YouT max and Voutmin on the plot. In the amplifier's linear range, determine and compare it with the calculated value for 4,2- AVOUT2 Avs2 in Step 7. From the simulation results of Step 6 above, obtain a plot of is2 as a function of Vs2: Avs2 Determine in the linear amplifier range and compare that value with the calculated value of R. 2: Ais2 Step 8. Consider the plots of both Step 5 and Step 6. Are Vout max and VouT min the same for both circuits? Consider the assumption that vy = Vp. Does the assumption hold when the output is saturated?