HELP : how to design a 3 inputs differential amplifier

[darlling5147]

I'm now trying to built a vectorcardiographic system with 3 leads as inputs to measure the heart electric pulse.

i just know how to built a ECG with 2 lead as input. i need help to implement a differential amplifier with 3 input.

below is the lead system.

 

[aomeen]

Hello,

How about cascading two differential amplifiers,

I understand you need fully diferential solution, and every single input is differential. you may use the output of first amplifier as one input to the second, with your third input as the second input..

Hope you got it

 

[darlling5147]

to : aomeen

IS THIS THE IDEA U TRYING TO TEACH ME? if yes,the resultant signal will be different from original o not?

**broken link removed**

 

[darlling5147]

**broken link removed**

halor.......can anyone tell me that is there any different if i amplified the electric signal immediately and amplified using cascade method. is the final signal grahp still the same pattern?

thx

Added after 3 minutes:




halor.......can anyone tell me that is there any different if i amplified the electric signal immediately with 1 amplifier and amplified using cascade method(means more than 1 amplifiers). is the final signal graph of the single amplifier same with the cascade amplifiers?

thx

 

[sec]

maybe you can put buffer or op-amp as voltage follower after amp 1, 2 and 3 and place 2 amp after.
on that reach amp 1 and 2 and the other reach 2 and 3

 

[darlling5147]

maybe you can put buffer or op-amp as voltage follower after amp 1, 2 and 3 and place 2 amp after.
ont that reach amp 1 and 2 and the other reach 2 and 3

erm....i cant get ur exact idea...can roughly draw me out the circuit to show me?
sorry for troubling u n thx very much for ur reply