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Design >> Analog Design >> How to evaluate specification of SAR ADC for biomedical(ECG)?
https://designers-guide.org/forum/YaBB.pl?num=1350463019

Message started by Penny3GS on Oct 17^th, 2012, 1:36am

Title: How to evaluate specification of SAR ADC for biomedical(ECG)?
Post by Penny3GS on Oct 17^th, 2012, 1:36am

Hi gentlemen

I want to design a SAR ADC but i don't know how to evaluate specification of SAR ADC.

Maybe thesis or book or any other application note can help me

I am doing some research and i got some result

Resolution:10 bits
channel:1 ch
sample rate:1kHZ (not sure)

ADC structure:
1.Charge-Redistribution
2.Binary weight
3.bipolar ADC
4.single end

Final target i need to do ultra low power for this ADC

So how to evaluate specification and reasonable?

Attach file is ECG waveform

Thanks for gentlemen

Title: Re: How to evaluate specification of SAR ADC for biomedical(ECG)?
Post by loose-electron on Oct 23^rd, 2012, 4:38pm

QRS complex waves eh?

Looks good, no atrial fibrillation, or tachycardia...

:)

Is this something you are designing into an IC or purchasing a device for off the shelf design?

You also mentioned low power and bipolar design.

If you are designing an IC consider CMOS to keep the power low.

Title: Re: How to evaluate specification of SAR ADC for biomedical(ECG)?
Post by Penny3GS on Oct 24^th, 2012, 12:00am

To loose-electron

Yes,i use TSMC 0.18 to design it,but still not sure the spec :-/

Title: Re: How to evaluate specification of SAR ADC for biomedical(ECG)?
Post by Lex on Oct 24^th, 2012, 12:31am

Interesting subject. Sadly I don't know much about it, but I'd guess you first need a SNR, BW and Voltage range requirement.

As loose-electron pointed out, there are many kinds of heart rhythms possible. I can image that in case of a fast heart rate (160 bpm or more) you'd still want accurate images so that probably defines your BW requirement. Very weak heart functioning (given small amplitude) will probably define your SNR. And so on.

Why don't you talk to a specialist/cardiologist to discuss the types of 'input signals' and output requirements (i.e. what is important for the persons inspecting the ECG)?

Title: Re: How to evaluate specification of SAR ADC for biomedical(ECG)?
Post by boe on Oct 24^th, 2012, 10:46am

Hi,

you should also consult the relevant standards.

- B O E

Title: Re: How to evaluate specification of SAR ADC for biomedical(ECG)?
Post by Penny3GS on Oct 25^th, 2012, 1:50am

Document link:(document size too large)

http://bme.ccny.cuny.edu/faculty/mbikson/Courses/BMESeniorDesign/BMESeniorDesign2007-2008/NASA%20ECG%20REPORT%201_050608.pdf

Title: Re: How to evaluate specification of SAR ADC for biomedical(ECG)?
Post by Penny3GS on Oct 25^th, 2012, 2:03am

To Lex and boe

I try to find standard for ECG application before,

unfortunately I can't find that (BTW if someone know standard for ECG application,please give me hand,thanks)

So second plan is find ECG sensor and follow up this spec for this application!

The document i attach in the my post,

and do a spec list below maybe everybody clond give me some opinion,thanks

SNR:60 dB

Feq:0~150 HZ

Voltage range:-0.2 mV~0.8mV

Title: Re: How to evaluate specification of SAR ADC for biomedical(ECG)?
Post by Lex on Oct 26^th, 2012, 5:19am

Needless to say maybe, but the 50/60 Hz is in your range. I don't know how large this interferer is at the point you measure, but I guess I'd like to prevent this signal clipping/distorting the readout circuit.

Title: Re: How to evaluate specification of SAR ADC for biomedical(ECG)?
Post by boe on Oct 29^th, 2012, 11:56am

Penny3GS,

Penny3GS wrote on Oct 25^th, 2012, 2:03am:

I try to find standard for ECG application before,

unfortunately I can't find that (BTW if someone know standard for ECG application,please give me hand,thanks)

I strongly recommend you make sure you know the relevant standards before trying to build such a system.

- B O E