ECG circuit development

[saur]

I am a newbee in using opamps and i want some help in building instrumentation amplifier using opamp.

I am planning to use INA 333 opamp for amplifying the low voltages(in microvolts) given out by sensors. But as my device is battery operated, i am unable to provide +(7 pin) and -(4 pin) voltages. I want to operate my circuit in a single supply mode instead of dual supply. As specified in website INA 333 is single supply opamp but it dint work. Will anybody help me in debugging this problem.

Also, if anybody has any document about internals of opamp(which is a differential opamp) to get to know about the equations and other details, please give me the links.

 

[(*steve*)]

Have a look at some of the chopper stabilised op-amps. If your signal is low frequency (essentially DC) then these are a really good alternative. Many have the ability to operate from very low supply rails (2 to 6V) and may be a viable alternative.

edit: OK, there's some information in the heading that's not in the body You'd have to look at the frequency response of the chopper amplifiers to see if it was compatible with the frequencies you're liable to come across.

 

[saur]

Thanks Steve.
The one thing that I am surprised about is that INA 333 is enlisted as single supply opamp by the link
http://focus.ti.com/apps/docs/viewd...63&blockId=7997&designOptionId=8512&appId=464

. But in actual sense, its difficult operate in that mode.

 

[KMoffett]

"But in actual sense, its difficult operate in that mode"

Did you look at Figure 37? What's difficulty that your encountering?

Ken