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What remedy can be followed to maintain the operating frequency in the op-amps?

(a) Use LC circuit

(b) Use resistor

(c) Use capacitor

(d) Use transistor

The question was posed to me in a national level competition.

Enquiry is from High Frequency Op-Amp Equivalent Circuit topic in portion Operational Amplifier Applications of Linear Integrated Circuits

1 Answer

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ago by (6.5k points)

To maintain the operating frequency in op-amps, especially when dealing with high-frequency behavior, the most suitable remedy would be:

(c) Use capacitor

Explanation:

At high frequencies, the op-amp’s performance can degrade due to internal capacitances and the reduced bandwidth. To maintain stable operation and prevent the op-amp from oscillating or losing gain, compensating capacitors are often used.

Capacitors help in controlling the frequency response and can be used to:

  • Improve stability: By compensating for the high-frequency roll-off, capacitors can help prevent oscillations by modifying the frequency response.
  • Compensate for parasitic capacitance: In high-frequency circuits, parasitic capacitance can affect performance. Using external capacitors can mitigate this impact.

For high-frequency operation in op-amps, the capacitor is often part of the compensation network, which is designed to ensure that the op-amp can operate at the desired frequency while maintaining stability.

Why not the other options?

  • (a) Use LC circuit: While LC circuits are used for oscillators or frequency tuning, op-amps typically use capacitors for frequency compensation and stability, not LC circuits.
  • (b) Use resistor: Resistors alone won't stabilize high-frequency performance effectively, though they may be part of feedback networks.
  • (d) Use transistor: While transistors are crucial in designing op-amps, they don't directly address the issue of maintaining frequency stability.

Thus, capacitors are commonly used to manage frequency behavior in op-amp circuits.

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