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Home ‣ Digital Electronics ‣ Interfacing to the Analog World See What Others Are Saying!
  • Question

  • Which of the statements below best describes the basic operation of a dual-slope A/D converter?


  • Options
  • A. The input voltage is used to set the frequency of a voltage-controlled oscillator (VCO). The VCO quits changing frequency when the input voltage stabilizes. The frequency of the VCO, which is proportional to the analog input voltage, is measured and is displayed on the digital display as a voltage reading.
  • B. A ramp generator is used to enable a counter through a comparator. When the ramp voltage equals the input voltage, the counter is latched and then reset. The counter reading is proportional to the input voltage since the ramp is changing at a constant V/second rate.
  • C. A ramp voltage and analog input voltage are applied to a comparator. As the input voltage causes the integrating capacitor to charge, it will at some point equal the ramp voltage. The ramp voltage is measured and displayed on the digital panel meter.
  • D. Two ramps are generated: one by the input voltage and the other by a reference voltage. The input voltage ramp charges the integrating capacitor, while the reference voltage discharges the capacitor and enables the counter until the capacitor is discharged, at which time the counter value is loaded into the output latches.

  • Correct Answer
  • Two ramps are generated: one by the input voltage and the other by a reference voltage. The input voltage ramp charges the integrating capacitor, while the reference voltage discharges the capacitor and enables the counter until the capacitor is discharged, at which time the counter value is loaded into the output latches. 

    • More questions

    • 1. When the outputs of several open-collector TTL gates are connected together, the gate outputs ________.

    • Options
    • A. usually burn out
    • B. produce more voltage
    • C. are ANDed together
    • D. produce more fan-out
      • Discuss
    • 2. The expression can be directly implemented using only ________.

    • Options
    • A. an XOR gate
    • B. an XNOR gate
    • C. an AOI circuit
    • D. three 2-input NAND gates
      • Discuss
    • 3. The commutative law of Boolean addition states that A + B = A × B.

    • Options
    • A. True
    • B. False
      • Discuss
    • 4. Solve this BCD problem: 0100 + 0110 =

    • Options
    • A. 00010000BCD
    • B. 00010111BCD
    • C. 00001011BCD
    • D. 00010011BCD
      • Discuss
    • 5. The serial format for transmitting binary information uses:

    • Options
    • A. a single conductor
    • B. multiple conductors
    • C. infrared technology
    • D. fiber-optic
      • Discuss
    • 6. Solve this binary problem:

    • Options
    • A. 11001001
    • B. 10010000
    • C. 01101110
    • D. 01110110
      • Discuss
    • 7. Binary subtraction of a decimal 15 from 43 will utilize which two's complement?

    • Options
    • A. 101011
    • B. 110000
    • C. 011100
    • D. 110001
      • Discuss
    • 8. If an analog signal is to be converted to an 8-bit resolution, how many comparators are used in a parallel-encoded ADC?

    • Options
    • A. 127
    • B. 128
    • C. 255
    • D. 256
      • Discuss
    • 9. If an input is activated by a signal transition, it is ________.

    • Options
    • A. edge-triggered
    • B. toggle triggered
    • C. clock triggered
    • D. noise triggered
      • Discuss
    • 10. The octal number for binary 1101110101110110 is ________.

    • Options
    • A. 6545218
    • B. 5565618
    • C. 1566568
    • D. 1565668
      • Discuss

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