Instrumentation Amplifier Questions and Answers for Viva

Answer-1: An instrumentation amplifier is a type of differential amplifier that is specifically designed for amplifying small differential signals while rejecting common-mode noise.

Answer-2: The primary function of an instrumentation amplifier is to amplify small differential signals accurately in the presence of common-mode noise.

Answer-3: An instrumentation amplifier typically consists of three operational amplifiers and precision resistors.

Answer-4: Instrumentation amplifiers offer higher input impedance, higher common-mode rejection ratio (CMRR), and better precision compared to differential amplifiers.

Answer-5: The CMRR of an instrumentation amplifier refers to its ability to reject common-mode signals. It is typically very high, often exceeding 100 dB.

Answer-6: High input impedance prevents loading effects on the signal source and ensures minimal signal distortion.

Answer-7: Precision resistors help maintain accurate gain and high CMRR in the instrumentation amplifier.

Answer-8: Instrumentation amplifiers are widely used in medical instrumentation, strain gauge amplification, bridge amplification, and sensor signal conditioning.

Answer-9: A single-ended input refers to a signal referenced to ground, while a differential input involves two signals with respect to each other.

Answer-10: Rail-to-rail output means that the output voltage of the instrumentation amplifier can swing from the lowest supply voltage to the highest supply voltage.

Answer-11: The gain (G) of an instrumentation amplifier is typically given by G = 1 + (2 * R₂ / R₁ ), where R₁ and R₂ are the values of the external gain-setting resistors.

Answer-12: An instrumentation amplifier rejects common-mode signals by providing high gain to the differential input while attenuating common-mode signals equally at both inputs.

Answer-13: Input bias current can affect the accuracy of the amplifier's output. Minimizing input bias current is important for high-precision applications.

Answer-14: Three-op-amp instrumentation amplifiers offer simplicity, flexibility, and high performance, making them suitable for various precision applications.

Answer-15: Instrumentation amplifiers often require dual power supplies, typically ranging from ±5V to ±15V.

Answer-16: Temperature variations can cause drift in gain and offset voltages of an instrumentation amplifier, affecting its accuracy and stability.

Answer-17: Input offset voltage refers to the voltage that must be applied between the inputs of an instrumentation amplifier to bring the output voltage to zero.

Answer-18: Key specifications include gain, CMRR, input impedance, bandwidth, noise level, and power supply requirements.

Answer-19: Lower noise levels result in higher signal-to-noise ratios (SNR), which is essential for accurate signal amplification, especially in low-level signal applications.

Answer-20: Yes, some instrumentation amplifiers are designed to operate with a single power supply, although they may have limitations compared to those with dual supplies.