7.1 Name THREE applications of an operational amplifier (op amp) - NSC Electrical Technology Power Systems - Question 7 - 2017 - Paper 1

1. Infinite open-loop gain: The ratio of output voltage to input voltage is infinitely high.
2. Infinite input impedance: No current flows into the input terminals.
3. Zero output impedance: The output can drive any load without significant voltage drop.

In an open loop configuration, the operational amplifier operates without any feedback from output to input. This results in the maximum voltage gain, but also makes the output highly sensitive to input variations.

A diagram should depict an op-amp with the non-inverting terminal connected to ground and the inverting terminal connected to the input signal. The output should indicate that it will switch based on the input signal level relative to a reference voltage.

Positive feedback occurs when a portion of the output signal is fed back to the input in phase with the input signal. This can lead to increased gain and potentially to amplification or oscillation.

The high input impedance means that the op-amp draws negligible current from the preceding circuit. Therefore, the voltage present at the preceding circuit remains largely unchanged, allowing for accurate signal processing.

1. Audio oscillators: Used for generating sound signals in synthesizers.
2. Electronic organs: For sound modulation and tone generation.
3. GPS units: For frequency modulation and signal conditioning.

The graph should show the input waveform and the corresponding output waveform, demonstrating phase relationships as per the operation of the comparator.

The resistor R provides feedback to the inverting input of the op-amp, allowing control over the gain and stability of the circuit.

If R is decreased, it results in a decrease in the voltage at the inverting input, which in turn increases the overall gain of the circuit due to the feedback mechanism.

R allows for greater control over the op-amp circuit gain. Setting R at a high value provides a voltage-follower configuration, stabilizing the output.

The circuit should include an op-amp with feedback components (inductors and capacitors) configured to generate oscillations, clearly labeled.

The output of the comparator will be zero. This is because a comparator only amplifies the difference between the two signals, and if they are equal, there's no difference to amplify.

The frequency of the waveform remains unchanged during amplification. The process affects amplitude, not frequency.

Natural oscillation frequency refers to the frequency at which a system naturally oscillates when not subjected to external forces. A graph showing three complete sine waves can illustrate this concept.

Operational amplifiers serve as buffers between stages to prevent loading effects and ensure signal integrity, maintaining high input impedance and low output impedance.

Non-inverting amplifiers are used when a signal needs to be amplified without inverting its phase. Example: Audio amplifiers, where maintaining the signal phase is critical for sound quality.