Time-of-flight sensor and method of operating the same

A time-of-flight (ToF) sensor comprising:

• a light source configured to emit a transmission light to an object;
• a pixel array including a depth pixel, wherein the depth pixel includes a plurality of taps configured to operate based on a plurality of demodulation signals having different phases with respect to a phase of the transmission light, each tap of the plurality of taps including a first transfer gate, a storage gate and a second transfer gate that are sequentially arranged between a photodiode and a floating diffusion region;
• and
• a row scanning circuit configured to:
• collect photo charge in a charge storage structure below the storage gate from the photodiode,
• transfer the collected photo charge from the charge storage structure to the floating diffusion region,
• perform a first data sampling operation corresponding to a first conversion gain by applying a turn-off voltage to the second transfer gate to set a capacitance of the floating diffusion region to a first capacitance, and
• perform a second data sampling operation corresponding to a second conversion gain smaller than the first conversion gain by applying the turn-off voltage to the storage gate and applying a turn-on voltage to the second transfer gate to increase the capacitance of the floating diffusion region to a second capacitance greater than the first capacitance,
• wherein the row scanning circuit is configured sense the photo charge stored in the floating diffusion region as a signal voltage during the first and second data sampling operations.

A method of operating a time-of-flight (ToF) sensor including a depth pixel, wherein the depth pixel includes a plurality of taps configured to operate based on a plurality of demodulation signals having different phases with each other, each tap including a first transfer gate, a storage gate and a second transfer gate that are sequentially arranged between a photodiode and a floating diffusion region, the method comprising:

• changing a capacitance of the floating diffusion region by controlling voltages applied to the storage gate and the second transfer gate;
• and
• performing a plurality of sampling operations corresponding to a plurality of conversion gains with changing the capacitance of the floating diffusion region,
• wherein each tab has one or more conversion gains.