GROL Amplifier and Oscillator Circuits 4

Question 1

Neutralization of an RF amplifier stage is performed to:

Accepted Answer

Cancel unwanted feedback caused by the transistor's internal collector-base capacitance

Answer

At high frequencies, the transistor's internal capacitance feeds energy back from output to input; neutralization applies equal and opposite feedback to cancel this effect and prevent oscillation.

Question 2

The 3 dB bandwidth of a single-tuned RF amplifier stage is determined by:

Accepted Answer

The ratio of resonant frequency to the circuit Q factor

Answer

Bandwidth equals the resonant frequency divided by the Q factor (BW = f₀/Q), so a higher Q circuit results in a narrower, more selective bandwidth.

Question 3

Intermodulation distortion (IMD) products are generated when:

Accepted Answer

Two or more signals pass through a nonlinear device, producing spurious sum and difference frequencies

Answer

Nonlinearities in an amplifier or mixer cause multiple input signals to mix, generating spurious output signals at sum, difference, and harmonic combinations of the input frequencies.

Question 4

Automatic Gain Control (AGC) in a communications receiver is used to:

Accepted Answer

Keep the receiver's audio output relatively constant despite varying received signal strength

Answer

AGC reduces the gain of the receiver's RF and IF amplifier stages when a strong signal is received, maintaining a relatively constant audio output level.

Question 5

Why is the noise figure of a receiver's first RF amplifier stage especially critical?

Accepted Answer

Noise introduced in the first stage is amplified by all subsequent stages, directly limiting receiver sensitivity

Answer

Any noise introduced in the first amplifier stage gets amplified by all subsequent stages, so a low noise figure in the front end is essential for good receiver sensitivity.

(GROL) General Radiotelephone Operator License Practice Test

(GROL) General Radiotelephone Operator License Practice Test

GROL Amplifier and Oscillator Circuits 4