7.1 Name TWO characteristics of an ideal op amp - NSC Electrical Technology Electronics - Question 7 - 2016 - Paper 1

The term bandwidth refers to the range of frequencies over which the op amp can amplify signals without significant distortion or loss of gain. It is the frequency range within which the gain remains acceptable and is crucial for determining the operational limits of the amplifier.

Positive feedback occurs when the output signal of an amplifier circuit is fed back into the input in such a manner that it reinforces the original input signal. This results in an increase in the overall gain of the system, leading to potential instability or oscillation.

The circuit symbol for an operational amplifier consists of a triangle shape with two inputs (inverting and non-inverting) and an output. The power terminals are typically marked as +V (positive supply) and -V (negative supply).

For the circuits in FIGURE 7.1 and FIGURE 7.2, the input and output waveforms should be drawn sinusoidal. The output in FIGURE 7.1 should be noted for its amplification and phase inversions corresponding to the input signals. The waveforms must overlap on the same y-axis for comparison.

The op-amp configuration can be identified as a non-inverting amplifier based on the arrangement of the input and feedback components in the circuit.

The input waveform should be a standard sine wave, while the output waveform will be the amplified version. Ensure that the two waveforms are labeled properly to distinguish between 'Input' and 'Output'.

The voltage gain ($A_V$) can be calculated using the formula: A_V = rac{V_{out}}{V_{in}} = 1 + rac{R_f}{R_{in}} Substituting the given values into the formula will yield the required gain.

To find the output voltage ($V_{out}$), we apply the earlier calculated voltage gain to the input signal: $V_{out} = A_V imes V_{in}$ Using the gain derived from the previous calculation will allow for this final value to be determined.

Two applications of an astable multivibrator circuit include:

1. Tone generator – used in sound production.
2. Clock pulse generator – serves as a timing source in digital circuits.

The input waveform depicted as a square wave in FIGURE 7.5 should be carefully sketched, with the corresponding output waveform illustrating the timing and phase relationship due to the bi-stable multivibrator's function.

The feedback used in the RC phase-shift oscillator is positive feedback, which is essential for sustaining oscillations in the circuit.

One application of the RC phase-shift oscillator is as a tone oscillator, used to generate audio frequencies.

The oscillation frequency ($f_{osc}$) for the RC phase-shift oscillator can be calculated using the formula: f_{osc} = rac{1}{2 ext{π} imes R imes C ext{(Total)}} Substituting the values of resistance and capacitance will give the frequency.

One application of the integrator circuit is signal conditioning, where it converts a step input into a ramp output.

In the integrator circuit, the input wave form is a square wave, while the output wave form is a triangular waveform showing the accumulation of the input signal over time.