Nondestructive readout mode static induction transistor (SIT) photo sensors

The nondestructive readout (NDRO) mode of op­ eration of image sensors is desirable to develop for the future intelligent image sensors. However, NDRO is not achievable with the conventional CCD image sensors. In this paper, we will examine the NDRO performance of two static induction transistor (SIT) photo sensors, a 40 x 40 pixel area array, and a 140-b linear array. We demonstrated NDRO operation in the SIT sensors by im­ aging with the area array and by examining the output wave­ form of the linear array. The charge lost per one NDRO cycle in the linear array was 0.014% near the saturation signal level and no charge loss could be detected at the ≤0.5 saturation level. NDRO performance in the area array was degraded com­ pared to the linear array. The degradation was due to the larger value of the load capacitance connected to the output electrode of the SIT. The NDRO operation also enables the cancellation of both the photosite reset noise and the signal nonuniformity by sub­tracting the first NDRO output from the following NDRO out­ puts, as well as an advantage to monitor the signal state during the integration period.