Question

An instrumentation amplifier has a high

• A. \( \text{Output impedance} \)
• B. \( \text{CMRR} \)
• C. \( \text{Input offset currents} \)
• D. \( \text{Supply voltage} \)

Hint:

Instrumentation amplifiers are specialized differential amplifiers commonly used in medical and industrial applications for accurate signal acquisition. Their primary advantages include very high input impedance, low output impedance, and, most importantly, high CMRR, which allows them to amplify small differential signals while rejecting common-mode noise.

Answer 1

The Correct Option is B

To solve this problem, we need to understand the key characteristics of an instrumentation amplifier and identify the one with the highest value from the options given.

1. Understanding Instrumentation Amplifiers:

- An Instrumentation Amplifier is a type of differential amplifier with additional input buffering to improve performance. It is designed for precise measurements of small differential signals, often used in sensor applications where high accuracy and stability are required.

Instrumentation amplifiers typically have the following key characteristics:

• High Common-Mode Rejection Ratio (CMRR): This is one of the most important characteristics. CMRR measures the amplifier’s ability to reject common-mode signals (signals that are present on both inputs) while amplifying the differential signal (the difference between the inputs). A high CMRR is essential for reducing the impact of noise or interference that is common to both input signals.
• Low Input Offset Currents: Input offset currents are small mismatches in the input bias currents of the two inputs, which can affect the accuracy of the differential signal measurement. Instrumentation amplifiers are designed to have low input offset currents.
• Low Output Impedance: This typically refers to the impedance seen at the output of the amplifier. While important, it is generally not as high a priority as CMRR in an instrumentation amplifier.
• Supply Voltage: The supply voltage is necessary to power the amplifier but does not typically define its performance in the context of signal processing and rejection of noise or common-mode signals.

2. Key Characteristic of an Instrumentation Amplifier:

The most defining feature of an instrumentation amplifier is its high Common-Mode Rejection Ratio (CMRR). This allows the amplifier to reject unwanted common-mode signals (such as noise or interference) and accurately amplify the differential signal.

Final Answer:

An instrumentation amplifier has a high CMRR (Common-Mode Rejection Ratio).