PROBLEM TO BE SOLVED: To provide the system satisfactory in bandwidth and transient response enough and capable of preventing the generation of fixed pattern noise caused by the changes of amplifier time constant and stray capacity by performing low noise amplification about the array of passive pixels. SOLUTION: Two correlation double sampling circuits are provided to improve sensitivity. A 1st circuit 42 reads a passive pixel 12 and connects a clamp switch 46 to reference voltage REF 2, and a CTIA 22 closes a reset switch 32 and holds it on a reset level. When the CTIA 22 is on the final reset level, a far edge of a capacitor 44 becomes the voltage REF 2, and column bus capacity and shot reset noise of an amplifier 24 are restrained. In a 2nd circuit 62, when a signal of a black pixel is read through the CTIA 22, the circuit 42 and an S/H buffer 50 at the time of frame start, a clamp switch 66 connects a capacitor 64 to reference voltage REF 3. When the CTIA 22 reaches a stable level, a far edge of the capacitor 64 becomes the voltage REF 3 and restrains pattern noise between columns.
CMOS PASSIVE PIXEL SENSOR SYSTEM AND READING CIRCUIT FOR THE SYSTEM