# US 7,746,311 B2 · Thin-film transistor circuit and a semiconductor display using the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,746,311 B2 - Document ID: US7746311B2 - Status: Granted - Kind: B2 - Application number: 11/413,759 - Filed: 2006-04-28 - Published: 2006-12-14 - Granted: 2010-06-29 - Earliest claimed: 1998-04-28 - Assignees: Semiconductor Energy Laboratory Co., Ltd. - Inventors: Shunpei Yamazaki; Jun Koyama - Web page: https://patentgrep.com/patent/US7746311B2 ## CPC - H10D 86/0251: {characterised by increasing the uniformity of device parameters} - G09G 3/3688: {suitable for active matrices only} - H03K 17/122: {in field-effect transistor switches} - G09G 3/3677: {suitable for active matrices only} - G09G 2320/0233: Improving the luminance or brightness uniformity across the screen - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00) - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) ## Abstract To provide thin-film transistor circuits used for a driving circuit that realizes a semiconductor display capable of producing an image with high resolution and high precision without image unevenness. TFTs with small channel widths are used to form an analog buffer which comprises a differential amplifier circuit and a current mirror circuit and which is used in a driving circuit of an active matrix semiconductor display. A plurality of such analog buffer circuits are connected in parallel to secure an analog buffer that has a sufficient current capacity. ## Claims ### Claim 1 A semiconductor device comprising: n analog buffer circuits directly connected in parallel, wherein n is a natural number equal to or greater than 2; each of the n analog buffer circuits having a differential circuit and a current mirror circuit, wherein the differential circuit comprising a first thin film transistor and a second thin film transistor, wherein one of source and drain of the first thin film transistor is electrically connected to one of source and drain of the second thin film transistor, and wherein the other one of source and drain of the second thin film transistor is directly connected to a gate electrode of the second thin film transistor, wherein the current mirror circuit comprising a third thin film transistor and a fourth thin film transistor, wherein one of source and drain of the third thin film transistor is electrically connected to one of source and drain of the fourth thin film transistor, and wherein the other one of source and drain of the third thin film transistor is electrically connected to a gate electrode of the third thin film transistor, wherein the n analog buffer circuits are inputted a signal, simultaneously. ### Claim 2 (depends on 1) A semiconductor device according to claim 1, wherein the first and second thin film transistors are P channel thin film transistors, and the third and fourth thin film transistors are N channel thin film transistors. ### Claim 3 (depends on 1) A semiconductor device according to claim 1, wherein the first and second thin film transistors are N channel thin film transistors, and the third and fourth thin film transistors are P channel thin film transistors. ### Claim 4 (depends on 1) A semiconductor device according to claim 1, wherein each of the first, second, third and fourth thin film transistors has a channel region comprising polycrystalline. ### Claim 5 (depends on 1) A semiconductor device according to claim 1, wherein the semiconductor device is applied to an electronic apparatus selected from the group consisting of a cellular phone, a video camera, a mobile computer, a head-mounted display, a rear type projector, a front type projector, a player that uses a recording medium that has recorded a program and a digital camera. ### Claim 6 A semiconductor device comprising: n analog buffer circuits directly connected in parallel, wherein n is a natural number equal to or greater than 2; each of the n analog buffer circuits having a differential circuit and a current mirror circuit, wherein the differential circuit comprising a first thin film transistor and a second thin film transistor, wherein one of source and drain of the first thin film transistor is electrically connected to one of source and drain of the second thin film transistor, wherein the other one of source and drain of the second thin film transistor is directly connected to a gate electrode of the second thin film transistor, and wherein a gate electrode of the first thin film transistor is electrically connected to an input terminal, and the gate electrode of the second thin film transistor is electrically connected to an output terminal, wherein the current mirror circuit comprising a third thin film transistor and a fourth thin film transistor, wherein one of source and drain of the third thin film transistor is electrically connected to one of source and drain of the fourth thin film transistor, and wherein the other one of source and drain of the third thin film transistor is electrically connected to the gate electrode of the third thin film transistor, wherein the n analog buffer circuits are inputted a signal, simultaneously. ### Claim 7 (depends on 6) A semiconductor device according to claim 6, wherein the first and second thin film transistors are P channel thin film transistors, and the third and fourth thin film transistors are N channel thin film transistors. ### Claim 8 (depends on 6) A semiconductor device according to claim 6, wherein the first and second thin film transistors are N channel thin film transistors, and the third and fourth thin film transistors are P channel thin film transistors. ### Claim 9 (depends on 6) A semiconductor device according to claim 6, wherein each of the first, second, third and fourth thin film transistors has a channel region comprising polycrystalline. ### Claim 10 (depends on 6) A semiconductor device according to claim 6, wherein the semiconductor device is applied to an electronic apparatus selected from the group consisting of a cellular phone, a video camera, a mobile computer, a head-mounted display, a rear type projector, a front type projector, a player that uses a recording medium that has recorded a program and a digital camera. ### Claim 11 A semiconductor device comprising: n analog buffer circuits directly connected in parallel, wherein n is a natural number equal to or greater than 2; each of the n analog buffer circuits having a differential circuit and a current minor circuit, wherein the differential circuit comprising a first thin film transistor and a second thin film transistor, wherein one of source and drain of the first thin film transistor is electrically connected to one of source and drain of the second thin film transistor, and wherein the other one of source and drain of the second thin film transistor is directly connected to a gate electrode of the second thin film transistor, wherein the current mirror circuit comprising a third thin film transistor and a fourth thin film transistor, wherein one of source and drain of the third thin film transistor is electrically connected to one of source and drain of the fourth thin film transistor, and wherein the other one of source and drain of the third thin film transistor is electrically connected to a gate electrode of the third thin film transistor, wherein the other one of source and drain of the first transistor is electrically connected to the other one of source and drain of the third transistor, wherein the other one of source and drain of the second transistor is electrically connected to the other one of source and drain of the fourth transistor, wherein the n analog buffer circuits are inputted a signal, simultaneously. ### Claim 12 (depends on 11) A semiconductor device according to claim 11, wherein the first and second thin film transistors are P channel thin film transistors, and the third and fourth thin film transistors are N channel thin film transistors. ### Claim 13 (depends on 11) A semiconductor device according to claim 11, wherein the first and second thin film transistors are N channel thin film transistors, and the third and fourth thin film transistors are P channel thin film transistors. ### Claim 14 (depends on 11) A semiconductor device according to claim 11, wherein each of the first, second, third and fourth thin film transistors has a channel region comprising polycrystalline. ### Claim 15 (depends on 11) A semiconductor device according to claim 11, wherein the semiconductor device is applied to an electronic apparatus selected from the group consisting of a cellular phone, a video camera, a mobile computer, a head-mounted display, a rear type projector, a front type projector, a player that uses a recording medium that has recorded a program and a digital camera. ### Claim 16 A semiconductor device comprising: a pixel matrix circuit; a source signal line side driving circuit; and a gate signal line side driving circuit; n analog buffer circuits directly connected in parallel in the source signal line side driving circuit, wherein n is a natural number equal to or greater than 2; each of the n analog buffer circuits having a differential circuit and a current mirror circuit, wherein the differential circuit comprising a first thin film transistor and a second thin film transistor, wherein one of source and drain of the first thin film transistor is electrically connected to one of source and drain of the second thin film transistor, and wherein the other one of source and drain of the second thin film transistor is directly connected to a gate electrode of the second thin film transistor, wherein the current mirror circuit comprising a third thin film transistor and a fourth thin film transistor, wherein one of source and drain of the third thin film transistor is electrically connected to one of source and drain of the fourth thin film transistor, and wherein the other one of source and drain of the third thin film transistor is electrically connected to a gate electrode of the third thin film transistor, wherein the n analog buffer circuits are inputted a signal, simultaneously. ### Claim 17 (depends on 16) A semiconductor device according to claim 16, wherein the first and second tin film transistors are P channel thin film transistors, and the third and fourth thin film transistors are N channel thin film transistors. ### Claim 18 (depends on 16) A semiconductor device according to claim 16, wherein the first and second thin film transistors are N channel thin film transistors, and the third and fourth thin film transistors are P channel thin film transistors. ### Claim 19 (depends on 16) A semiconductor device according to claim 16, wherein each of the first, second, third and fourth thin film transistors has a channel region comprising polycrystalline. ### Claim 20 (depends on 16) A semiconductor device according to claim 16, wherein the semiconductor device is applied to an electronic apparatus selected from the group consisting of a cellular phone, a video camera, a mobile computer, a head-mounted display, a rear type projector, a front type projector, a player that uses a recording medium that has recorded a program and a digital camera.