I have fabricated a 0.1Hz to 10Hz noise filter based on reference design TIPD122 for μV amplifier circuit testing. I am have problems with noise in the high-pass filter stage limiting the over device performance. When jumper JP7 is installed the high-pass filter input is grounded and I get at 45mVpp ripple at Vout. The complete filter has 100x gain for an input referred noise of 450μVpp! When I probe R9 at the HPF output I get a waveform exactly 1/10 the output so the source of the problem must be the HPF stage which is giving me a roughly 4.5mVpp output with the input grounded. This ripple is highly succeptible to mechanical stress on the board and even a light tough (no electrical contact) produces 200mV swings at the output. Can anyone advise me on tracking down this problem and understanding why this filter is so sensitive?