# US 9,040,897 B2 · Photo-sensing pixel circuit with conversion gain adjustment unit and image sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,040,897 B2 - Document ID: US9040897B2 - Status: Granted - Kind: B2 - Application number: 13/442,870 - Filed: 2012-04-10 - Published: 2013-08-15 - Granted: 2015-05-26 - Earliest claimed: 2012-02-10 - Assignees: Novatek Microelectronics Corp. - Applicants: Dong-Hai Huang - Inventors: Dong-Hai Huang - Web page: https://patentgrep.com/patent/US9040897B2 ## CPC - H10F 39/803: {Pixels having integrated switching, control, storage or amplification elements} - H01J 27/146: {End-Hall type ion sources, wherein the magnetic field confines the electrons in a central cylinder} - H10F 39/12: Image sensors - G01J 1/44: Electric circuits {(for command of an exposure part G03B7/02)} - G01J 2001/4406: {Plural ranges in circuit, e.g. switchable ranges; Adjusting sensitivity selecting gain values} - H10F 39/18: Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) ## Abstract A photo-sensing pixel circuit including a photo-sensing part, a transfer transistor, a plurality of adjustment transistors, and an output circuit is provided. The photo-sensing part senses a light source and generates a corresponding number of electrons. The transfer transistor coupled to the photo-sensing part has a floating node and converts the electrons generated by the photo-sensing part into a voltage signal. The adjustment transistors have a first end and a second end, wherein the first end is coupled to a power supply, and the second end is coupled to the transfer transistor via the floating node. The output circuit coupled to the transfer transistor outputs a sensing signal according to the voltage signal, wherein the sensing signal is corresponding to the brightness of the light source. The adjustment transistors operate in at least two operation modes. Different numbers of the adjustment transistors are turned on in different operation modes. ## Claims ### Claim 1 A photo-sensing pixel circuit, comprising: a photo-sensing part, sensing a light source, and generating a corresponding number of electrons; a signal conversion unit, coupled to the photo-sensing part, having a floating node, and converting the electrons into a voltage signal according to a conversion gain, the signal conversion unit comprising: a row select transistor, coupled to a source follower and an output circuit, and transmitting an amplified voltage signal to the output circuit, wherein the output circuit is coupled to a transfer transistor via the source follower and the row select transistor; a conversion gain adjustment unit, coupled to the signal conversion unit via the floating node, and adjusting the conversion gain; and the output circuit, coupled to the signal conversion unit, and outputting a sensing signal according to the voltage signal, wherein the sensing signal corresponds to the brightness of the light source, wherein the conversion gain adjustment unit operates in at least two operation modes, and a conversion gain in one of the operation modes is greater than a conversion gain in the other operation mode, wherein the conversion gain adjustment unit has a first end and a second end, the first end is coupled to a first power supply, and the second end is coupled to the floating node, wherein the conversion gain adjustment unit comprises: coupled between the first end and the second end, wherein the number of adjustment transistors is three or more, and wherein different numbers of the adjustment transistors are turned on in different ones of the operation modes, and the conversion gain of the signal conversion unit is adjusted according to the number of the adjustment transistors that are turned on, wherein the photo-sensing pixel circuit further comprises: a control unit, coupled to the output circuit, and adjusting the number of the adjustment transistors that are turned on according to the brightness of the light source corresponding to the sensing signal. ### Claim 2 (depends on 1) The photo-sensing pixel circuit according to claim 1, wherein the more adjustment transistors are turned on, the smaller the conversion gain of the signal conversion unit is. ### Claim 3 (depends on 1) The photo-sensing pixel circuit according to claim 1, wherein the first power supply resets the floating node when all of the adjustment transistors are turned on. ### Claim 4 (depends on 1) The photo-sensing pixel circuit according to claim 1, wherein the adjustment transistors are coupled between the first end and the second end in series. ### Claim 5 (depends on 1) The photo-sensing pixel circuit according to claim 1, wherein the signal conversion unit comprises: the transfer transistor, coupled to the photo-sensing part, and transmitting the photocurrent signal to the floating node; and the source follower, coupled to the floating node and a second power supply, and amplifying the voltage signal. ### Claim 6 (depends on 1) The photo-sensing pixel circuit according to claim 1, wherein the higher the brightness of the light source corresponding to the sensing signal is, the smaller the conversion gain adjusted by the conversion gain adjustment unit is. ### Claim 7 (depends on 1) The photo-sensing pixel circuit according to claim 1, wherein the lower the brightness of the light source corresponding to the sensing signal is, the greater the conversion gain adjusted by the conversion gain adjustment unit is. ### Claim 8 (depends on 1) An image sensor, comprising a plurality of photo-sensing pixel circuits described in claim 1. ### Claim 9 (depends on 1) The photo-sensing pixel circuit according to claim 1, wherein the control unit directly controls the conversion gain adjustment unit to adjust the conversion gain. ### Claim 10 A photo-sensing pixel circuit, comprising: a photo-sensing part, sensing a light source, and generating a corresponding number of electrons; a transfer transistor, coupled to the photo-sensing part, having a floating node, and converting the electrons generated by the photo-sensing part into a voltage signal; a plurality of adjustment transistors, having a first end and a second end, wherein the first end is coupled to a first power supply, and the second end is coupled to the transfer transistor via the floating node; an output circuit, coupled to the transfer transistor, and outputting a sensing signal according to the voltage signal, wherein the sensing signal corresponds to the brightness of the light source; and a row select transistor, coupled to a source follower and the output circuit, and transmitting an amplified voltage signal to the output circuit, wherein the output circuit is coupled to the transfer transistor via the source follower and the row select transistor, wherein the adjustment transistors operate in at least two operation modes, and in the different operation modes, a different number of the adjustment transistors are turned on, coupled between the first end and the second end in series, and wherein the number of adjustment transistors is three or more, wherein the photo-sensing pixel circuit further comprises: a control unit, coupled to the output circuit, and adjusting the number of the adjustment transistors that are turned on according to the brightness of the light source corresponding to the sensing signal. ### Claim 11 (depends on 10) The photo-sensing pixel circuit according to claim 10, wherein the first power supply resets the floating node when all the adjustment transistors are turned on. ### Claim 12 (depends on 10) The photo-sensing pixel circuit according to claim 10, further comprising: the source follower, coupled to the floating node, a second power supply, and the output circuit, and amplifying the voltage signal, wherein the output circuit is coupled to the transfer transistor via the source follower. ### Claim 13 (depends on 10) The photo-sensing pixel circuit according to claim 10, wherein the higher the brightness of the light source corresponding to the sensing signal is, the more adjustment transistors are turned on. ### Claim 14 (depends on 10) The photo-sensing pixel circuit according to claim 10, wherein the lower the brightness of the light source corresponding to the sensing signal is, the fewer adjustment transistors are turned on. ### Claim 15 (depends on 10) An image sensor, comprising a plurality of photo-sensing pixel circuits described in claim 10. ### Claim 16 (depends on 10) The photo-sensing pixel circuit according to claim 10, wherein the control unit directly controls the conversion gain adjustment unit to adjust the conversion gain.