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Analog-to-Digital Conversion
18 questions By Tony R. Kuphaldt
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Question 7 of 18
Explain the operating principle of this analog-to-digital converter circuit, usually referred to as a tracking converter:
Reveal answerThe binary counter will count up or down as necessary to “track” the analog input voltage, resulting in a binary output that continuously represents the input.
Follow-up question: this form of ADC is not very effective at following fast-changing input signals. Explain why.
Notes:Have your students express the answer to this question in their own words, not just copying the answer I provide. Aside from the flash converter, the tracking converter is one of the easiest ADC circuits to understand.
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Question 8 of 18
Explain the operating principle of this analog-to-digital converter circuit, usually referred to as a successive-approximation converter:
Note: the successive-approximation register (SAR) is a special type of binary counting circuit which begins counting with the most-significant bit (MSB), then the next-less-significant bit, in order all the way down to the LSB. At that point, it outputs a “high” signal at the “Complete” output terminal. The operation of this register may be likened to the manual process of converting a decimal number to binary by “trial and fit” with the MSB first, through all the successive bits down to the LSB.
Reveal answerThe successive approximation register counts up and down as necessary to “zero in” on the analog input voltage, resulting in a binary output that locks into the correct value once every n clock cycles, where n is the number of bits the DAC inputs.
Follow-up question: this form of ADC is much more effective at following fast-changing input signals than the tracking converter design. Explain why.
Notes:Have your students express the answer to this question in their own words, not just copying the answer I provide. Aside from the flash converter, the tracking converter is one of the easiest ADC circuits to understand.
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Question 9 of 18
Explain the operating principle of a single-slope ADC circuit, in your own words.
Reveal answerI won’t give away all the details here, but the single-slope converter uses an integrator and a binary counter, the binary output determined by how long the counter is allowed to count.
Notes:Tutorials abound on simple ADC strategies, so your students should have little problem locating an adequate explanation for the operation of a single-slope ADC.
