High School

Given a dual-slope ADC with:

- Vref = 95 mV
- First integration time = 88 ms
- Input voltage = 98.5 mV

Find the conversion time of the ADC.

A) 88 ms
B) 176 ms
C) 184 ms
D) 10.5 ms

Answer :

Final answer:

The conversion time of a dual slope ADC, given a Vref of 95 mV, an input voltage of 98.5 mV, and a first integration time of 88 ms, is approximately 179.24 ms. This is calculated by adding the fixed integration time to the product of the integration time and the ratio of the input voltage to the reference voltage.

Explanation:

To find the conversion time of a dual slope ADC, we need to apply the concept of the ADC's operation. The dual slope ADC works by first integrating the input voltage for a fixed period and then discharging, integrating in the opposite direction, until it reaches zero.

The conversion time depends on the ratio of the input voltage to the reference voltage and the fixed integration time.

Given:

- Reference voltage (Vref) = 95 mV

- Input voltage (Vin) = 98.5 mV

- First integration time (Tint) = 88 ms

The conversion time is calculated as follows:

Total conversion time (Tconv) = Tint + (Vin/Vref) × Tint

Plugging in the known values, it gives:

Tconv = 88 ms + (98.5 mV / 95 mV) × 88 ms

Now, performing the calculation:

98.5 mV / 95 mV = 1.0368

Tconv = 88 ms + 1.0368 × 88 ms

Tconv = 88 ms + 91.2384 ms

Tconv = 179.2384 ms (approximately 179.24 ms)

Therefore, the conversion time of the ADC is approximately 179.24 ms.