Whats the SNR value for TMS320xxx implemented in DSP/MCU?

[Circuit_seller]

SNR

Hi

I want to use TMS320F2811 ADC to perform FFT in the DSP, but i can not find anythings about the ADC SNR perfromance in the datasheet and user's guides. what is the typical SNR value for such ADCs implemented in DSPs or MCUs?

Regards

 

[jetset]

Re: SNR

Well if you take some time you can meassure it, you can make an analog notch filter, put at the output of the DSP, apply a test signal to the DSP and see quantization noise of the signal. Then you can compare quantization noise with the signal amplitude and make an estimation of SNR.

 

[spweda]

Re: SNR

Generally 1 bit = 6 dB SNR. Based on the bits of ADC (n bits) , you could estimate the SNR 6n.

 

[yeewang]

SNR

yes, 1 bit = multiply by 2.
20log2 = 6 dB

It's good to remember that for easy caculation.

 

[Circuit_seller]

Re: SNR

Hi

I have not enough time and a evaluation board to measure the SNR.
And the 6 * n formula is theoritical and can not be used for such ADCs.

Regards

 

[brmadhukar]

Re: SNR

Hi,
The minimum SNR that can be tolerated is dependent on the quantization levels and the supply voltage. The easiest way you can determine for the practical use is, quantize the signal which you want, take a dump and plot. You can determine if it is useful or not.
The quantization step should be less than the noise levels.
B R Madhukar

 

[boeysue]

Re: SNR

Try to search SNR measurement in national semiconductor.There is some document in this region.
SNR measure in FFT domain calculate the signal power to noise power bin except the DC value.

 

[SkyHigh]

Re: SNR

SNR is a relative value. It depends on the dynamic range in which your signal is going to swing and the background noises that are resident at the input of the ADC at which samples are taken at regular intervals. So... How would you suppose vendors to offer you this individualistic information?

What you can do is to decide upon the dynamic range DR, i.e. maximum and minimum analog voltage levels where your signal will comfortably swing. Then decide on the resolution (i.e. number of bits) you will need to fit this DR.

Also, measure background noises in the "no signal" or quiescent conditions of the transmisson medium that will eventually be connected to an ADC. Measure your signal that is you intend to the ADC.

Hand compute the SNR yourself and you will obtain a set of realistic data for you to make practical designs.

Data provided by vendors can only be used as reference. Test your systems first will give you a better picture what ADCs suit your application or for your DSP project.

 

[Circuit_seller]

Re: SNR

Hi

Manufacturer usually specifies SNR for ADCs in fullscale input, and i wanted to know SNR at the fullscale but TI did not specified SNR for the ADC.

Regards

 

[a_aziz]

SNR

HI.
THE SNR for the ADC relate to manufcturer.

 

[mahdithdn]

Re: SNR

Hi

i don't now what kind of ADC it is. but if it a mu-law compander the folowing formula can help you:
it can only calculate the SNR of quantization noise in ADCs.

SNR = a + 6.02 * n

a = 0 in general and

a = 4.77 - 20 log10(log(1+mu)) for mu-law companders

Regards