TW201220837A - Sensing pixel arrays and sensing devices using the same - Google Patents

Abstract

A sensing pixel array is provided and includes a plurality of pixels disposed in an array. Each pixel operates during an exposure period and a readout period and generates a readout signal. Each pixel includes a sensing unit and a sampling unit. The sensing unit senses light to generate a sensing signal during the exposure period. The sampling unit samples the sensing signal to generate a sensing output signal which serves as the readout signal during the readout period. During the exposure period, the sampling unit acts as a memory unit for storing an input signal and outputting an accessed output signal which serves as the readout signal.

Description

201220837 VI. Description of the Invention: [Technical Field] The present invention relates to a sensing pixel array, and more particularly to a sensing device in which a sensing pixel array has a sensing function and a memory function. [Prior Art] In general, a CMOS image sensor (CIS) has a higher degree of integration than a CCD image sensor. Therefore, the CIS can be embedded on a wafer together with the image sensing processor to perform better image processing. Image quality generally depends on the number of line buffers. Therefore, CIS with higher image quality requires a larger number of line buffers. However, a large number of line buffers result in higher cost of CIS and a larger area in CIS. Accordingly, it is desirable to provide a sensing device that senses a pixel array having sensing and memory functions to reduce the number of line buffers in the sensing device. SUMMARY OF THE INVENTION The present invention provides a sensing pixel array comprising a plurality of halogens. The elements are arranged in an array. Each element operates during an exposure period and during a read period and produces a read signal. Each element includes a sensing unit and a sampling unit. The sensing unit senses light during the exposure to produce a sensing signal. The sampling unit samples the sensing signal during the readout period to produce a sensed output signal as the readout signal. During the exposure period, the sampling unit acts as a memory unit for storing an input signal and outputting an access output signal as a readout signal. 201220837 The present invention provides a sensing device including a plurality of pixels, a code circuit, and a second decoding circuit. The elements are: placed in: array; "the element is operated during a period of exposure and during a readout period and is generated - read out". Each pixel includes a sensing unit and a pickup: sensing light during the exposure period to generate a sensing signal; and 2 3: measuring the signal to generate a sensing output signal as the reading # number. During the exposure period, the sampling unit ...

Π-input signal and output an access output signal; for: the second-first decoding circuit controls the sampling unit in the readout to enable (4) to sample the sensing signal early and generate a sensing output signal === Unit, storage: two consecutive mountains t - in some embodiments, the 'sensing device further includes a readout circuit for reading the readout signal from the sampling unit and processing the readout number. [Embodiment] The above-mentioned objects, features, and advantages of the present invention will be more apparent and understood, and the preferred embodiments and the accompanying drawings are described in detail. A sensing device in accordance with an embodiment of the present invention. Referring to the first sensing device 1, the sensing pixel array 10, the column decoding circuit 丨1 and red: the readout circuit 13, and the switching circuit 14 are included. The sensitized array of pixels 10 is shown in Figure 2 (shown in Figure 2) and these pixels are arranged on an array of columns and hard lines. Each pixel can be operated between the exposure fields and the readout 4, and a read signal SR is generated. Decoding circuits n and 12 are used to control the pixels of the 201220837 sensing pixel array 10 to produce a complex readout signal SR. The readout circuit 13 is used to read the readout signals SR from the sensed pixel array 10. The switching circuit 14 is coupled to a plurality of voltage sources. In this embodiment, five voltage sources VS1 to VS5 are taken as an example for explanation. Voltage sources VS1 to VS5 provide voltages AVDD, AVDD*3/4, AVDD*2/4, AVDD*l/4, and AGND (ground), respectively. Switching circuit 14 is operative to select to provide a voltage to one of voltage sources VS1 through VS5 to sense pixel array 10. Figure 2 is a diagram showing the sensing of each element in the halogen array 10 in accordance with an embodiment of the present invention. In Fig. 2, one of the elements in the sensing pixel array 10 is taken as an example, and the other elements have the same structure as in the second figure. For the sake of clarity, FIG. 2 also shows the switching circuit 14. The switching circuit 14 includes switches 14a to 14e coupled between the voltage sources VS1 VSVS5 and the pixel 2, respectively. Referring to FIG. 2, the halogen 2 includes a sensing unit 20 and a sampling unit 21. The sensing unit 20 senses light during exposure to generate a sensing signal SS. In this embodiment, the sensing unit 20 includes a photodiode PD having a cathode coupled to the node Ν20 and an anode coupled to ground (e.g., voltage source VS5). During exposure, the photodiode PD senses light to produce a sensed signal SS. During readout, sampling unit 21 is used to sample the sensed signal SS to produce a sensed output signal as read signal SR. During the exposure, the sampling unit 21 operates as the same memory unit for storing an input signal and outputting an access output signal as the read signal SR. Referring to Fig. 2, the sampling unit 21 includes a transfer element 21a, a reset element 21b, and a source follower 21c. In this embodiment, the transfer component 21a includes a transistor T20, and the control terminal receives a control signal SC, the input terminal of which is connected to the sensing unit 20 at the node N20, and the output terminal thereof is connected to the floating expansion 201220837

The scattered node FN. The reset element 21b includes an transistor Τ21, and its control terminal receives a reset signal SRE, its input terminal is coupled to the switching circuit 14, and its output terminal is coupled to the floating diffusion node FN. The source follower 21c includes an transistor 22. The control terminal of the transistor 22 is coupled to the floating diffusion node fn', and its turn-in terminal is coupled to the voltage source vsi (avdd), and its output terminal is coupled to the sense node NRe. In this embodiment, the floating diffusion node FN can store charge. In other embodiments, a storage element is coupled between the floating diffusion node FN and the ground, and the storage element replaces the floating diffusion node FN to store the load. The storage element can be a substantially capacitor or a parasitic capacitance of the transistor T22 in the source follower 32c. Fig. 3 is a timing chart showing the control signal sc and the reset signal SRE in Fig. 2. In the following, the operation of the pixel 2 will be described with reference to the second to fourth graphs. The monthly exposure period ΡΕχρ starts at the time point T1 and ends at the time point T2, and the readout period PRED starts at the time point Τ2 and ends at the time point τ3. Prior to pESP during the exposure period, one of the switches 14a-14c of the switching circuit 14 is turned on, for example, the switch 14d is turned on, and the corresponding transistor AVDD* 1/4 is supplied to the output terminal of the crystal T21. At the same time, the decoding unit η enables (Norway) = the signal SRE to conduct the transistor Τ2, and also enables the control signal % to the transistor T2G. Thereby, the transistor T21 traces the received voltage ν〇〇*ι/4 to its output to reset the level of the floating diffusion node FN. Therefore, the scattered node FN is at the falling f level during the subsequent operation in the readout period %. Further, since the transistor T20 is turned on, the charge on the cathode of the photodiode PD is refreshed (read esh). No. = time point T1 ' The decoding unit 11 reverses the de-rt reset signal 'to the transistor T21, and the decoding unit 11 also reverses the control signal 201220837 SC to turn off the transistor T20. During the exposure period ρΕχρ, the photodiode illuminates the light and accumulates the voltage on the cathode of the cathodic diode PD at its cathode according to the sensed light intensity. This is called the sensing signal ss ^ ° in the light of an embodiment. If you want the Alien 2 to run as a memory, do the following. During the exposure period Pexp 'the decoding circuit 12 turns on one of the plurality of switches 14a to 14c of the path I4, for example, the switch \ = is switched on and the corresponding voltage AVDD*3/4 is supplied to the conduction of the transistor T21 as an input signal. . At the same time, the decoding circuit 12 is enabled to reset the # terminal to conduct the transistor T21. The transistor T21 transmits this input signal to the complex terminal (i.e., the floating diffusion node FN) to store the voltage of the input signal = the output diffusion node FN. Therefore, pixel 2 acts as a memory cell, and a ^ wheel = signal. In addition, the transistor T22 of the source follower 21c is turned on or off according to the voltage of the input voltage (ie, the voltage on the floating diffusion node FN), and the access φ signal is turned on or off according to the transistor Τ22. It is generated at the output node NR as the readout signal SR. It is to be noted that, in the read period Pred, the read circuit 13 must read the read signal SR from the sense node NR of the sampling unit 21 and process the read signal SR. Next, the operation of PRED during reading will be described. At time point T2, the decoupling unit 11 again enables the reset signal SRE to conduct the transistor T21, and the transistor T21 again transmits the received voltage ACDD*1/4 to its output to reset the floating diffusion defect FN. Level. Next, the decoding unit 11 reverses the enable signal SRE at the time point T2a to turn off the transistor τ2 丨. At time 2 τπ ' the decoding unit u enables the control signal sc to conduct the crystal. Therefore, the transistor T2G transfers the sensing signal generated during the exposure period PE, s to the #-diffusion node FN. In other words, the sensing signal % 201220837 is sampled by the sampling unit 21. The node FN is reduced. The voltage at time and point is stored in the floating expansion P, pa Φ a ^ ” e, and the decoding unit 11 reverses the control signal SC to turn off the transistor T20. The voltage of the sensing signal SS (ie, the transistor 22 of ^21e) According to the pass or close. By this, the sense; column: the voltage of the diffusion node, and the readout signal is used as the readout signal team. At the time (4), the reading of the readout node is read. Output = fetch / sample from the sampling unit 21 out k 唬 SR, and process the read signal SR. Or as a; = example '昼素 2 can be used as - sensing cells to sense light, both: for e memory The cell is stored in the round signal, its exposure is pEXP, the tV object is referenced to f or corrected, and the crystal T2G is turned off, so the floating diffusion node exposure period ρΓρ ' _ the sensation signal SS on the lion is affected. Therefore, During the exposure period PPYD, the book goes from 0 to 1 · ^ to the floating diffusion section, and the memory is transmitted to transmit the above input signal P1" to store the memory 2 and according to the input signal, the access output signal is extracted as The signal SR is read. The sensing device 需要 requires fewer line buffers, thereby reducing the cost of the sensing device 1 and reducing its area. As shown in Fig. 2, the source follower 2ic of each pixel includes a transistor T22. In some embodiments, the source knower coupler 21 c configured in the same row of the plurality of cells share a current source and the current source is lightly connected to the respective sense nodes NR of the pixels arranged in the same row. Between ground and ground. In the embodiment of Fig. 3, during the readout period PRED, the readout circuit j 4 reads the readout signal 201220837 SR from the sense node NR of the sampling unit 21c. That is, the reading unit 14 reads the readout signal SR from the read node NR of the sampling unit 21c at the time point T2d. However, in other embodiments, a correlated double sampling (CDS) operation can be performed during the readout period PRED. In this case, the readout circuit 14 reads or samples the readout signal SR from the sense node NR of the sampling unit 21c at a point in time between the time points T2a and T2b, and has obtained a readout voltage. Then, the readout circuit 14 samples the readout signal SR at the time point T2d to obtain another readout voltage. Next, the read circuit 14 calculates the difference between the two read voltages, and the voltage difference indicates the intensity of the light sensed by the photodiode PD. The present invention has been disclosed in the above preferred embodiments, and is not intended to limit the scope of the present invention. Any one of ordinary skill in the art can make a few changes without departing from the spirit and scope of the invention. The scope of protection of the present invention is therefore defined by the scope of the appended claims. 201220837 [Simplified Schematic] FIG. 1 shows a sensing device according to an embodiment of the present invention; FIG. 2 shows a pixel according to an embodiment of the present invention; and FIG. 3 shows a control signal and a reset signal in FIG. Timing diagram. [Description of main component symbols] Fig. 1: 1~ sensing device; 11~ column decoding circuit; 13~ readout circuit; SR~ readout signal;

10~ sensing pixel array;; 11, 12~ column decoding circuit; 14~ switching circuit; VS1...VS5~ voltage source;

AVDD, AVDD*3/4, AVDD*2/4, AVDD*l/4, AGND~ voltage;

Figure 2: 2 ~ halogen; 20 ~ sensing unit; 21a ~ transfer element; 21c ~ source follower; N20 ~ node; PD ~ light diode; SRE ~ reset signal; 14a ~ 14e ~ switch; 21~sampling unit; 21b~reset element; FN~floating diffusion node; NR~reading node; SC~control signal; SS~ sensing signal; T20, T21, T22~ transistor; Fig. 3: 201220837

Pexp ΤΙ, ~ exposure period; Pr_ED ~ readout period; T2, T2a, T2b, T2c, T2d ~ time point °

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Claims (1)

201220837 VII. Patent application scope: 1. A sensing pixel array comprising: a plurality of pixels arranged in an array, wherein = period and - reading period are operated and generated - read signal: = two of the pixels The method includes: a sensing unit, wherein the sensing button is used to generate a sensing signal; and a sampling unit for sampling the sensing signal during the reading period to generate a sensing output signal And as the readout signal; wherein, during the exposure period, the sampling unit functions as a memory unit to store and input signals and output-access the output signal as the read signal 2. The sensing pixel array of claim 1, wherein the sampling unit comprises: a transfer component coupled to the sensing unit for transferring the sensing signal to a floating diffusion node during the readout period; An element coupled to the floating diffusion node for resetting the level of the floating diffusion node before the exposure period; and the source is connected to the floating diffusion node for light-fastening, according to the Sensing a voltage of the signal to generate the sensed output signal as the readout signal; wherein, during the exposure period, the transfer component does not transfer the sensed signal to the floating diffusion node, and the reset component transmits the input signal To the floating diffusion node. The method of claim 2, wherein the source follower generates an edge access output signal according to a voltage of the input signal during a 5 um exposure period, As the readout signal. 4. The sensor pixel array of claim 2, wherein the reset element comprises: a germanium transistor having an input coupled to one of the plurality of voltage sources and an output coupled to the floating diffusion node The input terminal receives power from one of the voltage sources before the exposure period, and the received voltage is transmitted to the output terminal to reset the level of the floating diffusion node; and Wherein, during the exposure period, the input terminal receives the voltage from the voltage, and the voltage is used as the input signal' and the input signal is transmitted to the output terminal. 5. The sensing pixel array of claim 2, wherein the sampling unit further comprises a storage device, the floating diffusion node. [6] The sensing pixel array according to claim 5, wherein the two storage elements are a substantial capacitor or a parasitic electric current of the source follower, 7. As claimed in claim 1 The sensing pixel array 'where, the sensing unit includes a photodiode for sensing light during the exposure to generate the sensing signal. 8. A sensing device comprising: a plurality of pixels configured in an array, wherein each of the (2)=4 out periods operates and generates a readout signal 2 14 201220837 a sensing unit for Sensing light during the exposure period to generate a sensing signal; and a sampling unit for sampling the sensing signal during the reading period to generate a sensing output signal as the readout signal; During the exposure period, the sampling unit acts as a memory unit to store an input signal and output an access output signal as the read signal; a first decoding circuit for controlling the sampling list during the readout period | a signal, wherein the sampling unit samples the sensing signal and generates the sensing output signal; and a second decoding circuit for controlling the sampling unit during the exposure period, so that the sampling unit stores the input signal and outputs This accesses the output signal. 9. The sensing device of claim 1, further comprising a readout circuit for reading the readout signal from the sampling unit and processing the readout signal. The sensing device of claim 8, wherein the sampling unit comprises: a transfer component coupled to the sensing unit, and controlled by the first decoding circuit during the readout period Transmitting the sensing signal to a floating diffusion node; a reset component, lightly connecting the transfer component to the floating diffusion node, and being controlled by the first decoding circuit to reset the floating diffusion node before the exposure period And a source follower coupled to the floating diffusion node for generating the sensed output signal as the readout signal according to the voltage of the sensing signal during the readout 15 201220837; Wherein, during the exposure period, the first decoding circuit controls the transfer element not to transfer the sensing signal to the floating diffusion node, and the second decoding circuit controls the reset element to transmit the input signal to the floating diffusion node . 11. The sensing device of claim 0, wherein, during the exposure period, the source follower generates the access output signal according to a voltage of the input signal as the readout signal. 12. The sensing device of claim 1, wherein the resetting component comprises: a Λ transistor having a control terminal for receiving a reset signal coupled to the input terminal of the plurality of voltage sources And reducing an output of the floating listening node; wherein, before the exposure period, the input receives a voltage from one of the voltage sources, and the first decoding circuit enables the reset signal to Controlling the transistor to transmit the received voltage to the output terminal to reset the level of the floating diffusion node; and/or, during the exposure period, the input terminal receives one of the voltage sources A voltage is used as the input signal, and the second decoding circuit causes the reset signal to cause the transistor to transmit the input signal to the output terminal. 13. The sensing device of claim 1, wherein the sampling further comprises a storage element that is coupled to the floating diffusion node. 14. The sensing device of claim 13, wherein the 201220837 device or one of the source follower parasitic storage elements is a substantial capacitance. The sensing device of claim 8, wherein the sensing unit comprises a photodiode for sensing light during the exposure to generate the sensing signal. 17