Methods, devices, and systems for improving (i.e., reducing) the settling time of an output signal read from a photo sensor and improving the PSRR of the supply voltage are disclosed, wherein a detected charge in a pixel is converted to a voltage and drives a source follower transistor. A bias transistor is coupled in series with the source follower transistor and includes an output therebetween. The bias transistor is driven to source a reduced current when the voltage results from a readout of a reset value of the pixel and the bias transistor is driven to source an enhanced current when the voltage results from a readout of a sensed signal value.