Hi guys,
I am designing a 12 lead ECG system based on the ADS1298. I wanted to ask you to take a look at my schematic for the ADS1298 section and give me your feedback about the implementation. I basically use the design provided on the ADS1298 ECG FE PDK removing some sections.
I haven't included the regulators, MCU and external oscillator on the schematic but they will be there. At this time I just need feedback on the ADS1298 part.
I plan to use a 6 power supply (4 AA batteries) and obtain AVDD, AVSS and DVDD using LDOs.
What do you think about the oscillator, why is an external oscillator used on the PDK instead of the internal? What advantages come from it? I am power limited so I would like to know what is the issue with the internal oscillator.
I don't include AC coupling since the bias point would be mid rail (GND for the dual supply topology).
I am including the diode clamps for patient protection.
My biggest question comes to the use of the shielding drive, what applications need it and what applications don't? I have tested the system using the ADS PDK and works just fine driving the cable shield to AGND. I am using the biometric cable mentioned on the PDK user's guide.
I will appreciate if you can provide any comment or advice on my design and any answer for the shield drive question would be great!
Best reagards,
Efrain Gaxiola
