ADC Flashcards
The process by which analog signals are converted to their digitized forms.
ANALOG TO DIGITAL CONVERSION
ADC occurs via three steps:
SQE
SAMPLING
QUANTIZATION
ENCODING
The analog signal is sampled at regular intervals of time.
Sampling
The sampling rate must be at least twice the highest frequency of the signal.
Nyquist Criterion
It is defined as the process of converting the continuous sample amplitude into a discrete amplitude.
QUANTIZATION
Quantization
Thus by then, the signal will be discrete in both: T_ and A_.
Time and Amplitude
The difference between the actual analog value and quantized digit value.
QUANTIZATION ERROR
It is the process which assigns ones and zeros (stream of bits) for every quantization level.
Encoding
The number of bits assigned for each level (n) depends on the __ (L); such that L=2^n
levels’ number
The resolution of the ADC is the smallest detectable change in voltage.
Ideal ADC
In an ___, the quantization error is uniformly distributed between
–Δ/2 and Δ/2.
Ideal ADC
Q = Δ = Q_ S_ = FS/LN
Quantization Step
Full scale/Level’s number
Types of ADCs
1. D C ADC
2. SAR ADC
3. I ADC
- SS
- DS
- R ADC
4. S-D ADC (over sampled ADC)
Direct conversion ADC
Successive approximation register (SAR) ADC
Integrating ADCs: single slope, dual slop, and ramp ADC
Sigma-Delta ADC (over sampled ADC)
It is one of the most popular ADCs for 8-16 bits
Successive approximation register (SAR) ADC
It has moderate conversion speeds. The conversion time is around 1µs
Successive approximation register (SAR) ADC
