Which device is described as converting analog ECG signals to digital data?

• A. Signal amplifier
• B. Analog-to-digital converter
• C. Digital signal processor
• D. Sample-and-hold circuit

Answer: (A)

Converting an analog ECG signal to digital data is done by an analog-to-digital converter. The ECG signal starts as a continuous voltage that changes over time, and to process it digitally you need to sample that waveform at discrete moments and assign each sample a finite digital value through quantization. That whole process—sampling plus quantization—is what the ADC handles. Before conversion, the signal is typically amplified to bring it into the ADC’s optimal input range and filtered to reduce noise and prevent aliasing. A sample-and-hold circuit may momentarily capture each instant value so the ADC can convert it accurately. After digitization, a digital signal processor can perform further analysis, but the actual conversion from analog to digital data is accomplished by the ADC, not the amplifier.