spottymaldoon
New Member
I have taken Analog Devices' standard application of their AD620 op amp to make the front end of an electrocardiograph (three electrodes are strapped to the subject).
In the attached schematic this is followed by a tunable 60 Hz notch filter with a dual op amp buffer stage and followed by a high pass filter (1000Mfd capacitor) at "B".
A simple op amp amplifier with gain 100 follows and the output is connected to a 10 bit 3 V A/D converter (using PIC24FJ).
I am worried about the placement of the high pass filter at "B" - its purpose is to minimize the grossest low frequency excursions of the signal (e.g when the subject moves) and I could have placed it at "A"
I'd be obliged if somebody would comment on this whole arrangement and whether the big cap would be better placed elsewhere? Please also comment on my switch to single power supply devices for the latter stages.
In the attached schematic this is followed by a tunable 60 Hz notch filter with a dual op amp buffer stage and followed by a high pass filter (1000Mfd capacitor) at "B".
A simple op amp amplifier with gain 100 follows and the output is connected to a 10 bit 3 V A/D converter (using PIC24FJ).
I am worried about the placement of the high pass filter at "B" - its purpose is to minimize the grossest low frequency excursions of the signal (e.g when the subject moves) and I could have placed it at "A"
I'd be obliged if somebody would comment on this whole arrangement and whether the big cap would be better placed elsewhere? Please also comment on my switch to single power supply devices for the latter stages.