A pixel (300, 301), comprising: a sample transistor having a gate, a drain, and a source, a layout of the sample transistor comprising a source region (420, 333) surrounding and coupled to a storage node, and a gate region (430, 332) disposed around at least three sides of the source region (420, 333) that operates as a charge barrier to shield the storage node, and a drain region (410, 331), wherein the gate region (430, 332) is between the drain region (410, 331) and the source region (420, 333); and a memory capacitor coupled to the storage node; a pre-charge transistor having a gate, a drain, and a source, wherein the memory capacitor has a terminal coupled to the drain of the pre-charge transistor and a second terminal coupled to the source of the pre-charge transistor; a first source follower transistor having a gate, a drain, and a source, the source of the first source follower coupled to the drain of the sample transistor and the drain of the first source follower coupled for receiving a first voltage; a photodiode having a first terminal coupled to the gate of the first source follower transistor and the second terminal coupled for receiving a second voltage; a reset transistor having a gate, a drain, and a source, the drain of the reset transistor coupled to the first voltage and the source of the reset transistor commonly coupled to the first terminal of the photodiode and to the gate of the first source follower transistor; a second source follower having a gate, a drain, and a source, the gate of the second source follower coupled to the source of the sample transistor and the drain of the second source follower transistor coupled for receiving the first voltage, wherein the commonly coupled source of the sample transistor, the drain of the pre-charge transistor, and the gate of the second source follower transistor serve as the storage node; and a row select transistor having a gate, a drain, and a source, the drain of the row select transistor coupled to the source of the second source follower transistor. a sample transistor having a gate, a drain, and a source, a layout of the sample transistor comprising a source region (420, 333) surrounding and coupled to a storage node, and a gate region (430, 332) disposed around at least three sides of the source region (420, 333) that operates as a charge barrier to shield the storage node, and a drain region (410, 331), wherein the gate region (430, 332) is between the drain region (410, 331) and the source region (420, 333); and a memory capacitor coupled to the storage node; a pre-charge transistor having a gate, a drain, and a source, wherein the memory capacitor has a terminal coupled to the drain of the pre-charge transistor and a second terminal coupled to the source of the pre-charge transistor; a first source follower transistor having a gate, a drain, and a source, the source of the first source follower coupled to the drain of the sample transistor and the drain of the first source follower coupled for receiving a first voltage; a photodiode having a first terminal coupled to the gate of the first source follower transistor and the second terminal coupled for receiving a second voltage; a reset transistor having a gate, a drain, and a source, the drain of the reset transistor coupled to the first voltage and the source of the reset transistor commonly coupled to the first terminal of the photodiode and to the gate of the first source follower transistor; a second source follower having a gate, a drain, and a source, the gate of the second source follower coupled to the source of the sample transistor and the drain of the second source follower transistor coupled for receiving the first voltage, wherein the commonly coupled source of the sample transistor, the drain of the pre-charge transistor, and the gate of the second source follower transistor serve as the storage node; and a row select transistor having a gate, a drain, and a source, the drain of the row select transistor coupled to the source of the second source follower transistor.