Subelement C: Receiving Systems – 10 Key Topics – 10 Exam Questions – 4 Drawings— Topic 22: Amplifiers
Question 8-22C5
Element 8 (RADAR)The high-gain IF amplifiers in a RADAR receiver may amplify a 2 microvolt input signal to an output level of 2 volts. This amount of amplification represents a gain of:
Explanation
The amount of amplification, or gain, in electronic circuits is commonly expressed in decibels (dB). For voltage gain, the formula is:
Gain (dB) = 20 * log10 (V_out / V_in)
In this case, the output voltage (V_out) is 2 volts, and the input voltage (V_in) is 2 microvolts (which is 2 x 10^-6 volts).
1. Calculate the voltage ratio:
V_out / V_in = 2 V / (2 x 10^-6 V) = 1 / 10^-6 = 1,000,000
2. Calculate the base-10 logarithm of the ratio:
log10 (1,000,000) = 6
3. Multiply by 20 to get the gain in dB:
Gain (dB) = 20 * 6 = 120 dB
Therefore, an amplification from 2 microvolts to 2 volts represents a gain of 120 dB. Options A, B, and D are incorrect as they would correspond to different voltage ratios. For example, 60 dB is a voltage ratio of 1,000, and 100 dB is a voltage ratio of 100,000.
Related Questions
8-22C3 The I.F. Amplifier bandwidth is:8-22C4 A logarithmic IF amplifier is preferable to a linear IF amplifier in a RADAR receiver because it:8-22C6 In a RADAR receiver AGC and IAGC can vary between:8-23C1 Which of the following statements is correct?8-23C2 Video amplifiers in pulse RADAR receivers must have a broad bandwidth because: