Define the following terms with reference to amplifier circuits: 5.1.1 Attenuation 5.1.2 High-pass filter 5.2 Explain the following categories of transistor amplifiers: 5.2.1 A small signal amplifier 5.2.2 A power amplifier 5.3 Refer to FIGURE 5.3 below and answer the questions that follow - NSC Electrical Technology Electronics - Question 5 - 2021 - Paper 1

A high-pass filter is a circuit that allows signals with frequencies higher than a certain cutoff frequency to pass through while attenuating signals with lower frequencies. This is useful in applications where it's necessary to block low-frequency noise or signals.

A small signal amplifier is used to amplify low-level input signals, such as those from sensors or audio equipment, to a more manageable level. This type of amplifier typically has a linear response over a small input range and is characterized by its voltage gain.

A power amplifier is designed to take a weak electrical signal and amplify it to a level strong enough to drive a load, such as a loudspeaker. It is typically used in audio applications, where it boosts the audio signal to a level that can produce sound output.

The DC load line is used to determine the operating point (Q-point) of a transistor in an amplifier circuit. It illustrates the relationship between the collector current and the collector-emitter voltage, helping designers ensure the transistor operates efficiently within its active region.

The gradients of DC load lines indicate the change in collector current with respect to collector-emitter voltage. A steeper gradient implies a higher increase in current with a given voltage, which can affect amplifier performance, including gain and linearity.

To calculate the value of the collector resistor ( $R_C$), the formula can be used:

$R_C = \frac{V_{CC}}{I_C}$

Where

• $V_{CC}$ is the supply voltage,
• $I_C$ is the collector current as observed from the load line.

By substituting the observed values from the graph, the resistor value can be computed.