ADC fundamentals — What is the proper type of input presented to an analog-to-digital converter?
Digital Electronics
Interfacing to the Analog World
Difficulty: Easy
Choose an option
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Aa voltage level
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Ba clock pulse
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Ca binary number
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Dany of the above
Answer
Correct Answer: a voltage level
Explanation
Introduction / Context: An analog-to-digital converter (ADC) senses an analog quantity and outputs a digital representation. Understanding which signals belong on the ADC input versus its digital interface prevents wiring and specification mistakes.Given Data / Assumptions:
- Most ADCs measure analog voltage; some measure current via shunts but internally sense voltage.
- ADCs often require a separate digital clock and control lines, but these are not the “input quantity” being converted.
- Outputs are digital words or serial bitstreams.
Concept / Approach: The convertible input is an analog voltage (or a voltage proportional to current). The ADC uses sampling circuits and comparators to map that voltage to a numeric code. Digital clocks and numbers relate to timing and results, not to the measured quantity.Step-by-Step Solution:
Present the analog voltage within the specified common-mode and range.Provide clock/control on separate pins as required by the interface.Read the converted binary code from the ADC’s digital outputs.Verification / Alternative check:
ADC datasheets specify input range and impedance for analog pins; clocks and codes appear only on digital interface pins.Why Other Options Are Wrong:
a clock pulse: Needed for timing but not the quantity being converted.a binary number: That is the ADC’s output, not its measured input.any of the above: Overly broad and incorrect for the measured quantity.Common Pitfalls:
Driving beyond allowable input range or without proper conditioning.Final Answer:
a voltage level