ECG ADC Buffer Flex Module

I will be putting up design information for the notch filter version in a new project - ExG Notch Flex Module. This design should have some application if implementing a digital notch filter or in use outdoors.

After a seminar by ST, I will be reworking the opamp to be a TSZ124. Also, Plessey recommends the low pass roll off be around 200Hz and that I use the 10x gain not the 50x gain sensors. So not the PS25251, but the PS25253 nor the PS25451, but the PS25454. The advanced Notch filter design works great, so I'll be releasing an updated version of it and this board (which is good for differential ADC) with a new low pass filter. I'll be working on a 2 channel design that utilizes the TSZ124 in both a filter and gain configuration soon.

I am working on an analog notch filter design to add. It will also utilize arrays of resistors as 1% and 5% resistor arrays are available. Selecting capacitors for size will be more complicated. The current schematic on github as "notch" uses arrays and an 0402 version of the Twin T notch filter is coming. I take feedback from the same op-amp and the Sallen Key is now 3rd order and much stronger. All this for only an additional capacitor per input over a non-active notch design added to the current ECG buffer design. I'll be working on the board layout to help improve my own testing of the ECG sensors.

I added new pictures showing the new castellations. We are still evaluating the design of this Flex Module as we are experimenting with various Plessey EPIC sensors.