Triple conversion gain image sensor pixels

Abstract

An image sensor having pixel circuitry operable in multiple gain modes is provided. The pixel circuitry may include first and second floating diffusion (FD) regions, a first photodiode coupled to the first FD region via a first transfer gate, a second photodiode coupled to the first FD region via a second transfer gate, a third photodiode coupled to the second FD region via a third transfer gate, and a fourth photodiode coupled to the second FD region via a fourth transfer gate. The first FD region may be coupled to the second FD region via first and second control transistors. The control transistors may be connected to a shared reset transistor. During readout, both control transistors may be deactivated to provide a high gain mode, only one transistor may be activated to provide an intermediate gain mode, or both control transistors may be activated to provide a low gain mode.