A PIXEL ARCHITECTURE AND AN IMAGE SENSOR
FIG2 is a schematic view of control signals for performing time-of-flight sensing by the image sensor
As illustrated in FIG2, pulsed light is emitted by the light source. The pulsed light is emitted during a time period T0. The pulsed light will be reflected by a target and the reflected light is received and detected by the image sensor 100. As illustrated in FIG2, the first exposure time and the second exposure time may be set such that part of the reflected light pulse is received by the pixel 110 during the first exposure time and part of the reflected light pulse is received by the pixel 110 during the second exposure time. A relation between the received light during the first exposure time and the received light during the second exposure time may form a measure of the distance to the target. As further illustrated in FIG2, a sequence of light pulses may be emitted. The first and second exposure times may have an identical relation to each of the light pulses in the sequence. This implies that the amount of light detected in a series of first exposure times may be accumulated within each pixel 110 and the amount of light detected in a series of second exposures times may be accumulated within each pixel 110. Thus, each pixel 110 may perform lock-in sensing so as to improve a signal-to-noise ratio for determining the distance to the target and hence improve accuracy of determining the distance.
schematic view
100
image sensor
110
pixel pixels
150
control unit
['1. A pixel architecture for detection of incident light; said pixel architecture comprising: an absorption layer (112), which is configured to extend in a first plane, the absorption layer (112) being configured for back-side illumination and being configured to generate charges in response to incident light on an interface of the absorption layer (112) and to transport charges in a direction perpendicular to the first plane; a semiconductor charge-transport layer (118) with a charge-dispatch region (120) and a charge node (128, 130); the charge-transport layer (118) being arranged to extend in a second plane parallel to the first plane, the charge-transport layer (118) being configured to receive generated charges from the absorption layer (112) and to transport the generated charges through the charge-transport layer (118), wherein one or more doped regions (122) are arranged in the charge-transport layer (118), wherein said charge-transport layer further comprises a bias region (121), and wherein the charge-dispatch region (120), which forms a dedicated region in a lateral direction parallel to the second plane of the charge-transport layer (118) is associated with the bias region (121); an electric connection (132) connecting to the bias region (121) for providing a selectable bias voltage to the bias region (121); and at least one transfer gate (124, 126) associated with an area adjoining to the charge-dispatch region (120) in the lateral direction, wherein the doped regions (122) and the bias region (121) have a different doping in relation to a bulk substrate of the charge-transport layer (118) and wherein the doped regions (122) and the bias region (121) are differently biased for driving transport of the generated charges towards the charge-dispatch region (120), and for controlling, together with the at least one transfer gate (124, 126), transfer of charges from the charge-dispatch region (120) in the lateral direction to the charge node (128, 130).', '12. An image sensor (100) comprising: an array of pixels (110), each having a pixel architecture according to any one of the preceding claims; and a control unit (150), which is configured to provide control signals for controlling transfer of charges from the charge-dispatch region (120) to the charge node (128, 130) of each pixel (110).']