Dear ADI team:
I was develop ADAU1772 project, and we have meet some issue need your check.
There was two confusion:
① In ADAU1772 Sigmastudio system, the General Filter integrated several EQ filter, but there was a different from ADAU176x/1701, 1772 EQ cannot shift 180 degree, it is a important factor to implement noise cancellation.
So pls help to point out how can I implement the 180 degree shift in all pass filter, or have other way to do it.
② the other question is also about the filter, in ADAU1772 Sigmastudio system, the all pole filter is a low pass filter with 180 degree shift, but the shift feature seems not work after AP test, and below is the test figure,
remark: red curve is bypass channel, blue curve is enable chennel, yellow curve is 180 shift channel.
figure 2 show frequency response is expectation,
figure 3 show phase curve, the blue and yellow curve coincide, means the 180 degree shift did not work.
So pls help to check the reason, and forward your feedback.