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7.1 Name THREE applications of an operational amplifier (op amp) - NSC Electrical Technology Electronics - Question 7 - 2017 - Paper 1
Question 7
7.1 Name THREE applications of an operational amplifier (op amp). 7.2 List THREE characteristics of an ideal operational amplifier (op amp). 7.3 Describe the term ... show full transcript
Worked Solution & Example Answer:7.1 Name THREE applications of an operational amplifier (op amp) - NSC Electrical Technology Electronics - Question 7 - 2017 - Paper 1
Step 1
Name THREE applications of an operational amplifier (op amp).
Answer
- Signal Conditioning: Operational amplifiers can be used to manipulate, filter, or amplify signals before further processing.
- Active Filters: They serve as the core component in designing various filter types, including low-pass, high-pass, and band-pass filters.
- Comparators: Op-amps are integral in creating comparator circuits, which compare two voltages and output a signal indicating which is higher.
Step 2
List THREE characteristics of an ideal operational amplifier (op amp).
Answer
- Infinite Input Impedance: This prevents current from flowing into the input terminals, ensuring that the op-amp does not load the previous stage.
- Zero Output Impedance: This allows the op-amp to output maximum power without any loss.
- Infinite Voltage Gain: The gain of the op-amp should be theoretically infinite, allowing for a very high amplification of the input signal.
Step 3
Describe the term open loop with reference to an operational amplifier (op-amp).
Answer
The term 'open loop' refers to an operational amplifier configuration in which there is no feedback from the output back to the input. In an open loop setup, the amplifier's gain is at its maximum, leading to significant amplification of the input signal. This mode, however, can result in saturation and distortion unless controlled.
Step 4
Draw the diagram of an operational amplifier (op amp) as an inverting voltage comparator.
Answer
The diagram should include an op-amp symbol with the input signal at the inverting terminal, a reference voltage at the non-inverting terminal, and an output label indicating the role of the op-amp as a comparator. Ensure to indicate the input and output voltage signals clearly.
Step 5
Step 6
Explain what effect the very high input impedance (close to infinity) of an op amp will have on the preceding circuit (circuit connected to the input of the op amp).
Answer
The very high input impedance of an operational amplifier means that negligible current will be drawn from the preceding circuit. This minimizes loading effects, ensuring that the voltage from previous stages remains largely unchanged and that the op-amp can accurately process the signal.
Step 7
Give THREE applications of RC phase shift.
Answer
- Phase Shift Oscillator: Used to generate sinusoidal waveforms by producing a specific phase relationship between amplifier and feedback circuit.
- Filters: Employed in designing low-pass and high-pass filters to control frequency response.
- Signal Conditioning: Useful in shaping signal behaviors for further processing in communication systems.
Step 8
With the given input signal at the non-inverting input, draw both the input and output signals on the same axis.
Answer
A sketch should show the input signal, typically a sine wave, at the non-inverting input and the corresponding output signal, which should reflect the amplified version of the input wave, maintaining the same phase.
Step 9
Explain the function of Rf in the circuit.
Answer
The resistor Rf is a feedback element that connects the output to the inverting input of the op-amp. It is crucial for controlling the gain of the operational amplifier and stabilizing the output by feeding back a proportion of the output voltage.
Step 10
Explain what will occur to the gain of the operational amplifier (op-amp) if the value of R is decreased.
Answer
If the resistance R is decreased, the voltage at the non-inverting input will also decrease, which results in a decreased gain of the operational amplifier. Consequently, this feedback affects the overall gain, as feedback is inversely related to R.
Step 11
Step 12
Step 13
A comparator circuit compares two electrical signals. State, with a reason, the nature of the output if both signals have exactly the same value.
Answer
If both input signals to the comparator are equal, the output will be stable and usually remains at a neutral value (which may often be set at 0V). This is because the comparator only amplifies the difference between the two input signals.
Step 14
Step 15
Explain the term natural oscillation frequency and draw THREE complete cycles to demonstrate natural oscillation frequency.
Answer
The natural oscillation frequency refers to the frequency at which a system oscillates when not subjected to any external force or damping. Drawing three complete cycles of a sinusoidal waveform will visually demonstrate this concept, indicating regular periodic behavior.
Step 16
Operational amplifiers are commonly used in complex circuits (between stages) to link the stages. State, with a reason, the application of this behavior.
Answer
Operational amplifiers are employed to adapt or match impedances between different circuit stages, ensuring maximum power transfer and minimizing signal loss. This buffering role is crucial in maintaining signal integrity.
Step 17
Once you use a non-inverting amplifier? Give ONE example to illustrate your answer.
Answer
A non-inverting amplifier is used when you require a voltage gain without inverting the signal phase. For instance, it is commonly found in audio equipment to amplify mic inputs while retaining the original signal characterization.