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Relation between sampling & resolution

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amit.31

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Hi,

i have some doubts regarding following questions:

how increase in sampling rate reduces resolution?
how dithering helps in sigma delta adc?
what actually noise shaping is?

any help would be greatly appreciated and thanks in advance.
 

it depends on the typr of ADC u use for example if you are using SA type it needs to make comparisons proportional to number of bits which means the resolution and of course you have to do that within 1 sampling period thats why they are connected
 

Hi,
You are referring the resolution to what?. Resolution is indeed the Events Per Unit Time.
I try to explain:
Digital Audio is measured in two ways:
Bit Rate Resolution and Sample Rate.

Sample Rate is the number of samples per second taken of the audio as if 1Hz = 1 sample per second. RedBook CD (RBCD) is 44.1kHz = 44,100 samples per second.

Bit Rate Resolution is the digital word length of each sample. This determines how precise each sample is. Think of it this way. You can explain last night's concert more precise using 100 words rather than using 20 words. So number of working expressing the concert is the resolution of Expression.
For Sigma Delta ADCs, visit the link for good explanation:
An Introduction to Delta Sigma Converters

Noise shaping is a technique typically used in digital audio, image, and video processing, usually in combination with dithering, as part of the process of quantization or bit-depth reduction of a digital signal. Its purpose is to increase the apparent signal to noise ratio of the resultant signal by altering the spectral shape of the error that is introduced by dithering and quantization such that the noise power is at a lower level in frequency bands at which noise is perceived to be more undesirable and at a correspondingly higher level in bands where it is perceived to be less undesirable.
Hope it helps a bit.
 
firstly thanks a lot Raza.

Hi,
You are referring the resolution to what?.

Bit Rate Resolution and Sample Rate.

i m referring to resolution of an ADC.
And could u explain me a bit more about "bit rate resolution" n also about "dithering" (like the example u have cited for bit rate resolution).

I also want ur suggestion regarding following:

Actually i have to work on CMOS implementation of an 40ksps and 12 bit resolution ADC.
So i searched n studied about it and found dat i can work with either SAR or delta sigma ADC.
Then i chose to start with the later option due to its several merits over SAR.

Now actually i want ur suggestion in d sense dat whether i m going in right direction or should i switch to SAR.

Thanks a lot in advance....wirh regards.

dont use this forum as your mobile by typing short forms of english words
 
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Hi amit,
Bit Rate Resolution:
Ok let separate these words like Bit Rate (BR) Resolution just to understand. Bit Rate is defining the rate of bits, Binary Digits 0, 1, 0, 1 (per unit time i,e; Second). Now if we divide the 1 second into 10 and then we divide it into 20, in first case we will have 10 happenings in one second and in second case the happenings will be 20 times in one second, means we can put more information in 20 times happening for the same times as compared to 10 times. This is known as RESOLUTION. In first case 10 and in second 20 (again remember this all refers to UNIT TIME). This will also increase the speed of work as the word length is increasing. It means more is the resolution more precise is the information. Let me put it little more elaborating :
Assume we have a picture and we call it a FRAME, now how many PIXELS are making this picture will be known as RESOLUTION and how many frames per unit time is the SAMPLING RATE. I think I can not text up more elaboration than this.
If I am working I would have preferred the Delta Sigma ADCs.
If any further question please ask without hesitation.
Good Luck.
 
Hello sir.
Yes i am very much clear with it now. And also today i decided to start working with sigma delta ADC.
Well sir,actually i have to do the CMOS implementaion of Delta Sigma ADC on Mentor Graphics. So can you help me like how should i approach now.
Like should i start using first order or second order or more higher order ADCs for my work.
Somewhere i have read that 5th order sigma delta ADC would be a better option for Audio and Voiceband applications.
 

hello sir.
i have studied the link that you and Mr.ckshivaram have given here.It has really helped me in understanding the basics of sigma delta adc but I have some confusion in last paragraph at page 6 and the figure 5(sigma delta modulator waveform) like how the decimation is being carried out by averaging the samples.Will you please help me out in visualising it.
 

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Hello Sir,

Hi amit,
Visit this link. It gives you an interactive tutorial of up to 512 loops. I this this explains a lot and will answer a lot of you in mind questions.

Which link sir?
 

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