What are two common signal conditioning techniques used for low-level sensors?

• A. Amplification with op-amps and high-pass filtering
• B. Amplification with op-amps and low-pass filtering
• C. Impedance matching and signal clipping
• D. Analog-to-digital conversion without conditioning

Answer: (B)

When you work with low-level sensors, the signal you get is tiny and easily overwhelmed by noise. The typical approach is to boost the signal and then clean it up before any digitization or further processing.

Amplification with op-amps is used because op-amps provide precise gain while presenting a high input impedance, so they don’t load the sensor. This lets you raise the signal to a usable level without distorting the source. In many cases, an instrumentation amplifier configuration is used to amplify small differential sensor voltages while rejecting common noise, which is especially helpful in noisy environments.

Low-pass filtering is applied to remove high-frequency noise from power supplies, electronics, and ambient interference. By limiting the bandwidth to what the sensor signal actually contains, you improve signal quality and also reduce the risk of aliasing when the signal is later sampled by an analog-to-digital converter.

High-pass filtering would remove the low-frequency or DC components that many sensors rely on, making it unsuitable as the standard pairing here. Clipping would distort the signal, and conditioning (not just raw ADC conversion) is typically needed to maximize resolution and accuracy. Impedance matching matters in certain contexts but doesn’t form the core dual technique shown here.

So the best combination is amplification with op-amps and low-pass filtering.