Question

UPLOAD PSPICE SIMULATION TO VERIFY CALCULATIONS

1- Design a lossy integrator op-amp circuit using op-amp 741. First, derive an expression for - Vo Then assign values to circuit components in order to have Gai 1. Verify your design with a PSpice simulation. Since gain value depends on Vi frequency, perform an AC sweep analysis (frequency response) to obtain which frequency gives you this gain. Report this trequency. IVil

Answer 1

Consider the Lossy integrator circuit using Op-amp C, VoWW Vi -o V In frequency domain 1 C joC

Draw the integrator circuit in frequency domain. Jo R -o V From the circuit V=0 For an ideal op-amp, the voltages at the inverting and non- inverting terminals are equal. V=V Thus Va V 0V Apply nodal analysis at node, V = 1-и и-л 1 -V o 0 + R jaC Vo Vi -=0 (V 0) 1 jaC V. 1 jaC V. Vi 1+joR,C R V R1joR,C Vi

V. Write the expression for gain, 1 V. Choose the values of R,, R,,C such that the gain is 1 Let R, 1k2 = R L=0.707k2 2 - С, -1uF Calculate the gain for these values V. R, V. 1 R,C R,C 2 1 =1 2 |V, 1 We can see that for the selected value of components, we = 1 get Calculate the value of w. 1 1 1 R,C, k1uF 10' (10) a 1000 27Tf 1000 1000 =159.15 160 Hz 27T f160 Hz So, for the selected components, at f 160 Hz the gain will be 1 Now let us verify this using PSPICE simulation

R1 1k C1 R2 1u 707.1 OPAMP OUT V1 1Vac V + OVdc U 1

[ D:pavani. PSpice sri_29-06-19-pspicefiles\schematic1\bias.sim ** Profile: "SCHEMATIC1-bias" Date Time run 06/29/19 17:00:15 Temperature: 27.0 (A) bias (active) 1.6V 1.4V 1.2v 1,0V 0.8v 0.6V 0.4V 300HZ 400HZ 100HZ 200HZ 500HZ OHz O V(R1:2) Frequency Page 1 Time: 17:01:22 Date June 29, 2019

From the graph we can see that at f 160 Hz, the gain 1 V.