Hello,
I'm designing a filter and amplifier for ECG signals.
The idea is to implement several stages:
- High input impedance stage (possibly with a little amplification, max gain of 4)
- Highpass filter (0.1 Hz, to get rid of DC before main amplification, multiple feedback, needs several uF capacitance)
- Amplification I
- Low pass
- Amplification II
The problem with my current design is, that the high input capacitance of the highpass makes the voltage follower in stage 1 oscillate (@ about 720 kHz). The datasheet of the TLV2772 , used in the current design, predicts such problems. Now I'm wondering which other amplifier might be suitet for this design or wehther it would be better to simply use an 'in-the-loop' or a 'snubber' compensation.
The parameters for the opamp are:
- 3.3V supply voltage
- Low noise (as low as possible)
- ability to drive high capacitive loads (5-10uF) in voltagefollower or noninverting amplifier configuration
- low supply current
Thanks for your feedback,
Steffen