Question

ECE 202- Experiment 3-PreLab Homework NTROD TION TOTHE INTEG IRO T OP AMP VOLTAGE COMPARATOR 1. Op Amp functions in two different modes, depending on the way it is connected in the circuit a) If there is no return loop, t is used to compare values of two input terminals (or as Explain how vo changes depending on the values of vi and v Vo . what are max and/or min values for v and vo? 2·The circuit shown below is a voltage comparator. Note that this circuit has no feedback and is not an amplifier; the output voltage is not proportional to the input voltage. Its output is, ideally, either Vec or-Ve depending on the instantaneous value of the inputs vi and v2 Plot vo vs. , fr V.-4 V and Vin (r)= 2.5 sin( 2劝) V with f-200 Hz; Remember that vo= +5V for +2.5V +5V R V Vin 0 aV .5V

Answer 1

I shall describe the ideal om-Amp scenario rightarrow If v_1 > v_2, then v_0 = -v_cc If v_2 > v_1, then v_0 = + v_cc As per theory, - v_cc lessthanorequalto v_1 lessthanorequalto + v_cc - v_cc lessthanorequalto v_2 lessthanorequalto + v_cc Therefore max (v_1) = + v_cc min (v_1) = -v_cc Therefore max (v_2) = + v_cc min (v_2) = -v_cc also, max (v_0) = + v_cc min (v_0) = -v_cc \r\n v_ref = R_x/R_x + R_x V_x = 1/2. 4v = 2 (v) rightarrow v_ref = v_- = 2 (v) Also, v_+ = v_in = 2.5 sin (2 pi/T t) T rightarrow Times period of the sinusoidal signal rightarrow \r\n Because v_in (t) = 2.5 sin (2 pi ft) and f = 200 (Hz) = v_+ Therefore T = 1/f = 1/200 = 5 (m sec) So, we shall draw the graph showing v_0 in MATLAB for a time range of (0, 10 m sec). This will cover 2 time period of the sinusoid

MATLAB CODE ==>

clear
clear all
t = 0:0.000001:0.01; %time range and samples for the plot
v2 = 2.5*sin(2*pi*200*t); % v+ input
v1 = 2; % v- input
k = 0;
for(tt = 0:0.000001:0.01)
k = k+1;
if(v2(k) >= v1) % comparison
vo(k) = 5;
elseif(v2(k) < v1) % comparison
vo(k) = -5;
end
end
plot(t,v2) % plot v+
figure
plot(t,vo) % plot vo
  

RESULTS ==>

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