Correct Answer - Option 1 : Sigma delta
Explanation:
- An analog signal first undergoes the process of sampling before it is applied to ADC for conversion into a digital signal.
- Oversampling is a process in which an analog signal is sampled at a sampling frequency that is much greater than the Nyquist rate.
- A Sigma-Delta ADC is an example of an ADC that employs oversampling.
- It is the same as “Delta modulation”. That is 1 sample is represented with 1 bit.
- In oversampling correlation increases and Quantization noise decreases.
To reduce the Quantization noise two things are done.
Oversampling and Noise shaping.
Oversampling is:
fs' = K × fs , ( K > 1)
The transfer function for Noise shaping is given by
\(H\left( s \right) = \frac{1}{{s + 1}}{V_{in}} + \frac{s}{{s + 1}}Q\)
\(\frac{1}{s + 1}\) : Acts as LPF for Vin and as an HPF for Quantization noise.
Q: Quantization noise
