Image sensors and optical devices
What is the main advantage of the scheme used in many CMOS image sensors in which each pixel column has its own AD converter for parallel conversion?
- AColor filters become unnecessary
- BPixel size can be doubled
- CCompared with converting every pixel in turn with one ADC, a high frame rate is achieved with slower ADCs
Show answer and explanation
Answer: C. Compared with converting every pixel in turn with one ADC, a high frame rate is achieved with slower ADCs
In the column-parallel ADC scheme, an AD converter is placed for each column of the pixel array, and a whole row of pixels is converted at once. Each ADC has an entire row time for its conversion, so slow, low-power circuits can deliver a high overall frame rate with low noise.
- A. Color filters are still needed to obtain color information.
- B. It is unrelated to pixel size.
- C. Correct. Parallel conversion speeds things up.