Dual storage node pixel for CMOS sensor
View Patent ↗A sensor includes control circuitry and a pixel. The pixel includes a photo site, a first storage node and a second storage node. The control circuitry causes the pixel to transfer a first collected signal from the photo site to the first storage node during a first period, to transfer a second collected signal from the photo site to the second storage node during a second period that follows the first period, and to transfer the first and second collected signals out of the pixel during a third period that follows the second period.
1. A sensor comprising:
a pixel that includes a first storage node, a second storage node and a photo detector that is one of a photodiode and a pinned photodiode; and
control circuitry to transfer a first collected signal from the photo detector to the first storage node during a first period, to transfer a second collected signal from the photo detector to the second storage node during a second period, and to transfer the first and second collected signals out of the pixel during a third period that follows the second period,
wherein the first storage node includes a first charge holding capacitor, a first charge transfer gate, and a first reset gate coupled to the first charge holding capacitor, the first charge transfer gate being coupled between the first charge holding capacitor and the photo detector,
wherein the second storage node includes a second charge holding capacitor, a second charge transfer gate and a second reset gate coupled to the second charge holding capacitor, the second charge transfer gate being coupled between the second charge holding capacitor and the photo detector,
wherein the first reset gate is coupled between the first charge holding capacitor and a first reset signal,
wherein the control circuitry is coupled to the first reset gate of the first storage node to provide a first reset gate control signal, and
wherein the control circuitry controls a potential of the first reset signal to be less than a potential of the first reset gate control signal minus a transistor threshold voltage.
2. The sensor of claim 1 , wherein the potential of the first reset gate control signal differs from the potential of the first reset signal by the transistor threshold voltage.
3. A sensor comprising:
a pixel that includes an output buffer, a first storage node, a second storage node and a photo detector that is one of a photodiode and a pinned photodiode; and
control circuitry to transfer a first collected signal from the photo detector to the first storage node during a first period, to transfer a second collected signal from the photo detector to the second storage node during a second period, and to transfer the first and second collected signals out of the pixel during a third period that follows the second period,
wherein the first storage node includes a first charge holding capacitor and an output voltage switch coupled between the first charge holding capacitor and the output buffer,
wherein the second storage node includes a second charge holding capacitor and an output voltage switch coupled between the second charge holding capacitor and the output buffer,
wherein the reset gate is coupled between the input of the output buffer and a reset signal,
wherein the control circuitry is coupled to the reset gate to provide a reset gate control signal, and
wherein the control circuitry controls a potential of the reset signal to be less than a potential of the reset gate control signal minus a threshold voltage.
4. The sensor of claim 3 , wherein the potential of the reset gate control signal differs from the potential of the reset signal by a transistor threshold voltage.