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KCC's quizzes AQQ260 about a technical article correction

1. Quote of the week: "No man goes before his time - unless the boss leaves early" - Groucho Marx

             

2. New quiz AQQ260 about a technical article correction

One (external) reader has noticed a mistake or imprecision in an ADI technical article:

https://www.analog.com/en/resources/technical-articles/adc-architectures.html

 The “faulty” section is displayed here below (note the BU is checking this for a coming quick update):

Questions:

  1. What and where is the error or imprecision?
  2. How would you correct it?

Good luck! And try to be among the firsts!

Kuo-Chang

P.S. Don't hesitate to share those weekly quizzes in EZ to colleagues or friends!

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Parents
  • 1. "The time it takes for the integrator to trip the comparator is proportional to the unknown voltage (TINT/VIN)". This is wrong. Also the relation TINTVIN on the right side of fig. 1b is not correct.

    2. Correction: "The time it takes for the integrator to trip the comparator is inversely proportional to the unknown voltage (TINT  1/VIN)". And on the right side of fig. 1b we need to put TINT  1/VIN.

Reply
  • 1. "The time it takes for the integrator to trip the comparator is proportional to the unknown voltage (TINT/VIN)". This is wrong. Also the relation TINTVIN on the right side of fig. 1b is not correct.

    2. Correction: "The time it takes for the integrator to trip the comparator is inversely proportional to the unknown voltage (TINT  1/VIN)". And on the right side of fig. 1b we need to put TINT  1/VIN.

Children
  • Thanks Gaetano! Indeed the error is indeed the time here is inversely proportional to Vin. OK, you propose the correction in the sentence. But the circuit, as it is, will not work as a single slope ADC! Changes must be done on the circuit for sure... Do you have an idea?

  • You need to swap VIN and Vref in the circuit (and Vref needs to be negative for positive VIN). This way the "ramp" coming out from the integrator has always the same slope and you have direct proportionality between TINT and VIN

  • Bingo Gaetanao! That's the (mnimu) correction the BU has to do on that article! Congratulations!