# US 2009/0267652 A1 · Methods and circuits for triode region detection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2009/0267652 A1 - Document ID: US20090267652A1 - Status: Published application - Kind: A1 - Application number: 12/111,114 - Filed: 2008-04-28 - Published: 2009-10-29 - Earliest claimed: 2008-04-28 - Assignees: Atmel Corporation - Inventors: Hendrik Santo; Kien Vi; Dilip S - Web page: https://patentgrep.com/patent/US20090267652A1 ## CPC - H03K 17/18: Modifications for indicating state of switch - 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 The present invention relates to circuits and methods for detecting transistor operation in the triode region including a circuit for a transistor in a constant current source. The circuit comprises a detector having a first input, a second input, and an output. The first input of the detector is coupled to the source of the transistor and the second input of the detector is coupled to the set point terminal of the constant current source. The circuit also comprises a flag coupled to the detector output. The detector has parameters selected so that, when the voltage at the source of the transistor satisfies a reference condition, the output of the detector sets the flag. The reference condition is established relative to the voltage at the set point terminal of the constant current source and relative to the triode transition voltage of the transistor at a selected drain-source current. ## Claims ### Claim 1 A circuit for detecting operation in the triode region of a transistor in a constant current source comprising: a detector having a first input, a second input, and an output, wherein the first input of the detector is coupled to the source of the transistor and the second input of the detector is coupled to the set point terminal of the constant current source; and a flag coupled to the output of the detector; the detector having parameters selected so that, when the voltage at the source of the transistor satisfies a reference condition, the output of the detector sets the flag, wherein the reference condition is established relative to the voltage at the set point terminal of the constant current source and relative to the triode transition voltage of the transistor at a selected drain-source current. ### Claim 2 (depends on 1) The circuit of claim 1, wherein the output of the detector sets the flag when the voltage at the source of the transistor is less than the voltage at the set point terminal of the constant current source plus a constant. ### Claim 3 (depends on 1) The circuit of claim 1, wherein the output of the detector sets the flag when the voltage at the source of the transistor is less than the voltage at the set point terminal of the constant current source times a constant. ### Claim 4 (depends on 1) The circuit of claim 1, wherein the selected drain-source current is the present drain-source current of the transistor. ### Claim 5 (depends on 1) The circuit of claim 1, wherein the selected drain-source current is the maximum designed-for drain-source current of the transistor. ### Claim 6 (depends on 1) A liquid crystal display comprising the circuit of claim 1. ### Claim 7 A circuit for detecting operation in the triode region of a transistor in a constant current source comprising: a detector having a first input, a second input, and an output, wherein the first input of the detector is coupled to the gate of the transistor; a program voltage source coupled to the second input of the detector; and a flag coupled to the output of the detector; the detector having parameters selected so that, when the voltage at the gate of the transistor satisfies a reference condition, the output of the detector sets the flag, wherein the reference condition is established relative to the voltage at the program voltage source and relative to the triode transition voltage of the transistor at a selected drain-source current. ### Claim 8 (depends on 7) The circuit of claim 7, wherein the output of the detector sets the flag when the voltage at the gate of the transistor deviates from the voltage at the program voltage source by more than a constant. ### Claim 9 (depends on 7) The circuit of claim 7, wherein the output of the detector sets the flag when the voltage at the gate of the transistor deviates form the voltage at the program voltage source by more than the voltage at the program voltage source times a constant. ### Claim 10 (depends on 7) The circuit of claim 7, wherein the selected drain-source current is the present drain-source current of the transistor. ### Claim 11 (depends on 7) The circuit of claim 7, wherein the selected drain-source current is the maximum designed-for drain-source current of the transistor. ### Claim 12 (depends on 7) A liquid crystal display comprising the circuit of claim 7. ### Claim 13 A circuit for detecting operation in the triode region of a transistor in a constant current source comprising: a detector having a first input, a second input, and an output, wherein the first input of the detector is coupled to the gate of the transistor; a program voltage source coupled to the second input of the detector, wherein the voltage at the program voltage source is established relative to the triode transition voltage of the transistor at a selected drain-source current; and a flag coupled to the output of the detector; the detector having parameters selected so that, when the voltage at the gate of the transistor satisfies a reference condition, the output of the detector sets the flag, wherein the reference condition is established relative to the voltage at the program voltage source. ### Claim 14 (depends on 13) The circuit of claim 13, wherein the output of the detector sets the flag when the voltage at the gate of the transistor deviates from the voltage at the program voltage source more than a constant. ### Claim 15 (depends on 13) The circuit of claim 13, wherein the output of the detector sets the flag when the voltage at the gate of the transistor deviates from the voltage at the program voltage source by more than the voltage at the program voltage source times a constant. ### Claim 16 (depends on 13) The circuit of claim 13, wherein the selected drain-source current is the present drain-source current of the transistor. ### Claim 17 (depends on 13) The circuit of claim 13, wherein the selected drain-source current is the maximum designed-for drain-source current of the transistor. ### Claim 18 (depends on 13) A liquid crystal display comprising the circuit of claim 13. ### Claim 19 A method for detecting operation in the triode region of a transistor in a constant current source comprising: detecting the voltage at the source of the transistor; detecting the voltage at the set point terminal of the constant current source; establishing a reference condition relative to the voltage at the set point terminal of the constant current source and relative to the triode transition voltage of the transistor at a selected drain-source current; determining if the voltage at the source of the transistor satisfies the reference condition; and setting a flag if the reference condition is satisfied. ### Claim 20 (depends on 19) The method of claim 19, further comprising determining if the voltage at the source of the transistor deviates from the voltage at the set point terminal of the constant current source by more than a constant. ### Claim 21 (depends on 19) The method of claim 19, further comprising determining if the voltage at the source of the transistor deviates from the voltage at the set point terminal of the constant current source by more than the voltage at the set point terminal of the constant current source times a constant. ### Claim 22 (depends on 19) The method of claim 19, wherein the selected drain-source current is the present drain-source current of the transistor. ### Claim 23 (depends on 19) The method of claim 19, wherein the selected drain-source current is the maximum designed-for drain-source current of the transistor. ### Claim 24 A method for detecting operation in the triode region of a transistor in a constant current source comprising: detecting the voltage at the gate of the transistor; detecting the voltage at a program voltage source; establishing a reference condition relative to the voltage at the program voltage source and relative to the triode transition voltage of the transistor at a selected drain-source current; determining if the voltage at the gate of the transistor satisfies the reference condition; and setting a flag if the reference condition is satisfied. ### Claim 25 (depends on 24) The method of claim 24, further comprising determining if the voltage at the gate of the transistor deviates from the voltage at the program voltage source by more than a constant. ### Claim 26 (depends on 24) The method of claim 24, further comprising determining if the voltage at the source of the transistor deviates from the voltage at the program voltage source by more than the voltage at the program voltage source times a constant. ### Claim 27 (depends on 24) The method of claim 24, wherein the selected drain-source current is the present drain-source current of the transistor. ### Claim 28 (depends on 24) The method of claim 24, wherein the selected drain-source current is the maximum designed-for drain-source current of the transistor. ### Claim 29 A method for detecting operation in the triode region of a transistor in a constant current source comprising: detecting the voltage at the gate of the transistor; establishing the voltage of a program voltage source relative to the triode transition voltage of the transistor at a selected drain-source current; detecting the voltage at the program voltage source; establishing a reference condition relative to the voltage at the program voltage source; determining if the voltage at the gate of the transistor satisfies the reference condition; and setting a flag if the reference condition is satisfied. ### Claim 30 (depends on 29) The method of claim 29, further comprising determining if the voltage at the gate of the transistor deviates from the voltage at the program voltage source by more than a constant. ### Claim 31 (depends on 29) The method of claim 29, further comprising determining if the voltage at the source of the transistor deviates from the voltage at the program voltage source by more than the voltage at the program voltage source times a constant. ### Claim 32 (depends on 29) The method of claim 29, wherein the selected drain-source current is the present drain-source current of the transistor. ### Claim 33 (depends on 29) The method of claim 29, wherein the selected drain-source current is the maximum designed-for drain-source current of the transistor.