Which term describes a signal conditioning element at the input that boosts the voltage to a level appropriate for the controller?

• A. u/U
• B. P/U
• C. Amplifier
• D. Transistor

Answer: (C)

The input signal needs to be scaled up to what the controller’s input can accept, and that is done by an amplifier. An amplifier increases the voltage (or current) of the sensor signal while keeping distortion low and, often, presenting a high input impedance to avoid loading the source. This makes the signal large enough for the controller’s ADC or analog input to read accurately and reliably. In instrumentation practice, the front-end signal-conditioning stage is designed around an amplifier (often an op-amp based circuit) to provide the required gain and buffering. While a transistor can perform amplification, the common term for the dedicated input-stage device described is amplifier. The other terms don’t describe this front-end conditioning function in typical instrumentation terminology.