Fingerprint sensing arrangement and a method for filtering a fingerprint pattern signal

A fingerprint sensing arrangement for sensing a fingerprint pattern of a user's finger for providing a fingerprint pattern signal, the fingerprint sensing arrangement comprising:

• an array of sensing elements for sensing the fingerprint pattern, each sensing element is configured to provide a sensing signal indicative of a local fingerprint pattern feature,
• a filter bank configured to suppress common mode noise, and configured to receive analog sensing signals from each of a set of sensing elements comprising at least four sensing elements,
• the filter bank is further configured to calculate a set of filtered output signals, each of the filtered output signals comprises a linear combination of the set of sensing signals in which each sensing signal is associated with a respective coefficient, wherein the coefficients in each linear combination sum up to zero and wherein the linear combinations are different from each other, and
• an analog to digital converter configured to convert the set of filtered output signals to set of filtered digital sensing signal indicative of the user's fingerprint pattern.

A control unit for providing a filtered fingerprint pattern signal indicative of fingerprint pattern of a user's finger based on sensing signals acquired with a fingerprint sensing device comprising an array of sensing elements for sensing the fingerprint pattern, each sensing element is configured to provide a sensing signal indicative of a local fingerprint pattern feature,

• the control unit being configured to:
• receive analog sensing signals from each of a set of sensing elements comprising at least four sensing elements,
• perform filtering of the set of sensing signals for common mode noise suppression, and to provide a set of filtered output signals, each of the filtered output signals comprises a linear combination of the set of sensing signals in which each sensing signal has a respective coefficient, wherein the coefficients in each linear combination sum up to zero, and wherein the linear combinations are different from each other, and
• convert the set of filtered output signals to a set of filtered digital sensing signals indicative of the user's fingerprint pattern.