Single-slope (ramp) A/D converter operation Which statement best describes the basic operating principle of a single-slope A/D converter?

Introduction / Context:
Single-slope (ramp) A/D converters are classic measurement circuits in panel meters and simple data acquisition. They trade speed and noise rejection for simplicity.

Given Data / Assumptions:

• The converter generates a known, linear ramp (constant V/second).
• A comparator detects when the ramp crosses the unknown input voltage.
• A digital counter measures ramp time from start to crossing.

Concept / Approach:
If the ramp slope is constant, the time to reach the unknown input is proportional to the input magnitude. Counting clock pulses during this interval yields a digital number proportional to the analog input.

Step-by-Step Solution:
Start ramp at a known time and zero level.Enable counter simultaneously and feed clock pulses.Comparator trips when ramp voltage equals input voltage.Latch the count, reset ramp and counter for the next measurement.

Verification / Alternative check:
Contrast with dual-slope ADCs (integrate input for a fixed time, then de-integrate with a reference) and SAR ADCs (binary search). The single-slope clearly matches the ramp-and-count description.

Why Other Options Are Wrong:
VCO frequency measurement (option A) describes a voltage-to-frequency converter based ADC, not single-slope.Integrating to match a ramp (option C) confuses integrator methods with dual-slope behavior.“Any of the above” (option D) is too broad; specific architectures differ.PWM duty cycle (option E) describes a different modulation-based scheme.

Common Pitfalls:
Assuming single-slope provides good noise rejection like dual-slope; it does not, since noise directly perturbs the trip timing.

Final Answer:
A ramp generator enables a counter through a comparator; when the ramp equals the input, the counter is latched and reset. The count is proportional to the input.