CMOS Image Sensor with Area-Efficient Correlated Double Sampling
Scheme  Capacitive-type CMOS fingerprint sensors have advantages
of compact-size and low-power consumption compared to optical
sensors because they require no additional components such as
light source and optical lens. Therefore, they are attractive to
mobile applications. However, they suffer from image degradation
for skin conditions known as dry and wet fingers. The other
issue is the parasitic capacitances connected with the sensing
electrode. These parasitic capacitances should be eliminated to
reduce the required dynamic range of the readout circuitry and
increase sensitivity. It is reported that the capacitively-
coupled cells using pixel-parallel neuron-MOS logic circuits
could give more accurate binarized image and the shield metal
with its voltage controlled by an additional amplifier could
reduce the parasitic capacitances.  In this work, a virtually-
grounded metal shield effectively suppresses the parasitic
capacitances without extra