question_answer

(i) Write the truth table for the following circuit. Name the equivalent gate that this circuit represents.

(ii) Two identical amplifiers are connected one after the other in series (cascaded). The first amplifier has a voltage gain of 20. If the input signal is 0.01 V then calculate the output of AC signal.

 

Answer:

(i) The logic combination of the given circuit is Truth Table

A	B	\[O{{P}_{1}}\]	\[O{{P}_{2}}=Y\]
0	0	0	1
0	1	1	0
1	0	1	0
1	1	1	0

            Hence, the given circuit performs the function of an AND gate. (ii) \[{{V}_{1}}={{V}_{2}}=20\] Input signal voltage, \[{{V}_{i}}=0.01V\] Output AC signal voltage, \[{{V}_{o}}=?\] The total voltage gain of two stage cascaded amplifier is given by the product of voltage gains of both the stages. Then,    \[{{V}_{\text{gain}}}{{V}_{1}}\times {{V}_{2}}=20\times 20=400\] We have the relation, \[V=\frac{{{V}_{o}}}{{{V}_{i}}}\,\,or\,\,{{V}_{o}}={{V}_{gain}}\times {{V}_{i}}\] \[=400\times 0.01=4V\] Therefore, the output AC signal of the given amplifier is 4V.