Active pixel sensors are described in U.S. pat. no. 5,417,215. Higher charge and efficiency from these devices is desirable. In addition, different parameters and operations can benefit from different kinds of samples. For example, a short sampling period can provide the highest amount of dynamic range, while a longer sampling period can provide better resolution. Fossum and Yadid-Pecht have described one such system and xe2x80x9cWide Intrascene Dynamic Range CMOS APS Using Dual Sampling, IEEE Transactions On Electronic Devices, volume 44 page 1721-1723, October 1997. In that system, two signals are obtained using two different integration intervals.
The present application teaches a new pixel design with dual floating diffusion regions, each of which is separately controlled. The two regions collectively provide dual integration, but do so in a way that increases sensitivity, allows dual dynamic range, and also provides multiple junctions for improved photocarrier detection.