Question

48 You are given two amplifiers, A and B, to connect in cascade between a 10-mV, 100-k source and a 100- load. The amplifiers have voltage gain, input resistance, and output resistance as follows: for A, 100 V/V, 100 k,10k, respectively; for B, 10 V/V, 10 k,1 k, respectively. Your problem is to decide how the amplifiers should be connected. To proceed, evaluate the two possible connections between source S and load L, namely, SABL and SBAL. Find the voltage gain for each both as a ratio and in decibels. Which amplifier arrangement is best?

Answer 1

To decide how the amplifiers should be connected, evaluate the SABL and SBAL connections. The SABL connection has a higher gain, making it the best arrangement.

Step-by-step explanation:

To decide how the amplifiers should be connected, we need to evaluate the two possible connections between the source and the load, SABL and SBAL. SABL connection: In this connection, amplifier A is first connected to the source and then amplifier B is connected to the output of amplifier A. The voltage gain in this case is the product of the voltage gains of both amplifiers, so it would be (100 V/V) * (10 V/V) = 1000 V/V. In decibels, this would be approximately 60 dB. SBAL connection: In this connection, amplifier B is first connected to the source and then amplifier A is connected to the output of amplifier B. The voltage gain in this case is the sum of the voltage gains of both amplifiers, so it would be (100 V/V) + (10 V/V) = 110 V/V. In decibels, this would be approximately 40 dB.

Based on the voltage gains, the SABL connection has a higher gain (1000 V/V) compared to the SBAL connection (110 V/V). Therefore, the SABL connection is the best amplifier arrangement.