Block-diagram-level amplifier design. In a certain application, an amplifier is
ID: 1571580 • Letter: B
Question
Block-diagram-level amplifier design. In a certain application, an amplifier is needed to sense the open-circuit voltage of a source and force current to flow through a load. The source resistance and load resistance are variable. The current delivered to the load is to be nearly independent of both the source resistance and load resistance. What type of ideal amplifier is needed? If the source resistance varies from 1 k omega to 2k omega and this causes a 1% decrease in load current, what is the value of the input resistance? If the load resistance varies from 100 omega to 300 omega and this causes a 1% decrease in load current, what is the value of the output resistance? Consider whether zero or infinite input resistance would be best for sensing the open-circuit voltage of the source. Consider whether zero or infinite output resistance would be best for making the load current independent of the load resistance. Based on these selections of input and output resistances, use Table 1.1 on page 39 to select the amplifier type.Explanation / Answer
1) Here, infinite input resistance would be best for sensing open circuit voltage . This is due to high output voltage gain .
2) Here, zero output resistance would be best for making the load current independent of load resistance . This is due to low output voltage gain .