Method of reading out a cmos image sensor and a cmos image sensor configured for carrying out such method

A method of reading out a CMOS image sensor, the CMOS image sensor comprising an array of pixels (Pxl) for sensing incident light, wherein each pixel (Pxl) comprises a largely-pinned photo-diode (Dde) arranged in reverse-bias, a first capacitance (C_low) arranged parallel to the largely-pinned photo-diode (Ddw), a switch (T_sw), a second capacitance (C_high) that can be switched in parallel with the first capacitance (C_low) by closing the switch (T_sw), and reset circuitry (T_res) for resetting a pixel potential (Vp) on the cathode of the photo diode (Dde) to a predefined voltage (V_ref),

• wherein each respective pixel (Pxl) can be set in a second mode (LS) by switching on the switch (T_sw) and thereby switching the second capacitance (C_high) parallel to the first capacitance (C_low), and wherein each respective pixel (Pxl) can be set in a first mode (SS) by switching off the switch (T_sw) disabling the second capacitance (C_high),
• the method comprising the steps of:
• setting a respective pixel (Pxl) in the first mode (SS);
• resetting the respective pixel (Pxl) such that the predefined voltage (V_ref) is set over the photo-diode (Dde) and the first capacitance (C_low);
• collecting charge carriers generated by the incident light on the respective photodiode (Dde), wherein the collected charge carriers reduce the pixel potential (Vp) on the respective photo-diode (Dde);
• reading out the respective pixel (Pxl) while set in the first mode (SS) and storing the pixel potential (Vp) that was read as a first potential value;
• reading out the respective pixel (Pxl) while set in the second mode (LS) and storing the pixel potential (Vp) that was read as a second potential value;
• resetting the respective pixel (Pxl) such that the predefined voltage (V_ref) is set over the photo-diode (Dde), the first capacitance (C_low), and the second capacitance (C_high);
• reading out the respective pixel (Pxl) while set in the second mode (LS) and storing the pixel potential (Vp) that was read as a third potential value;
• and
• reading out the respective pixel (Pxl) while set in the first mode (SS) and storing the pixel potential (Vp) that was read as a fourth potential value, and
• wherein a pinning potential of the largely-pinned photo-diode (Dde) is lower than a lower limit of the linear range of the pixel potential (Vp) such that within the linear range of the pixel (Pxl) the photo-diode (Dde) does not substantially store the charge carriers generated by the incident light.