Electronics Engineering (ELEX) Board Practice Exam

What is the critical frequency of the output RC circuit for a FET amplifier?

1. 46 MHz

2. 30 MHz

3. 60 MHz

4. 20 MHz

The correct answer is: 46 MHz

To determine the critical frequency of the output RC circuit for a FET amplifier, it's important to understand that the critical frequency, often referred to as the cutoff frequency, is determined by the resistive and capacitive elements in the circuit. The critical frequency \( f_c \) is calculated using the formula: \[ f_c = \frac{1}{2\pi RC} \] where \( R \) is the resistance and \( C \) is the capacitance in the circuit. In this context, if the answer provided points to a frequency of 46 MHz, it indicates a specific combination of R and C values that yields this frequency. This frequency would be relevant for determining the bandwidth and response characteristics of the amplifier, as it represents the point at which the output power drops significantly, typically to half of its maximum value. The choice of 46 MHz suggests that this particular R-C combination is optimized for achieving the desired frequency response in the FET amplifier, aligning perfectly with the operational needs of high-frequency applications common in electronics. Therefore, understanding the significance of the critical frequency in the function of a FET amplifier is crucial. This frequency helps in analyzing circuit performance and ensuring the amplifier operates effectively within its intended bandwidth, which is foundational