# US 11,029,714 B2 · Flipped gate current reference and method of using > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,029,714 B2 - Document ID: US11029714B2 - Status: Granted - Kind: B2 - Application number: 16/870,382 - Filed: 2020-05-08 - Published: 2020-08-27 - Granted: 2021-06-08 - Earliest claimed: 2014-09-30 - Assignees: Taiwan Semiconductor Manufacturing Company, Ltd. - Applicants: Taiwan Semiconductor Manufacturing Company, Ltd. - Inventors: Mohammad Al-Shyoukh; Alexander Kalnitsky - Web page: https://patentgrep.com/patent/US11029714B2 ## CPC - G05F 1/46: wherein the variable actually regulated by the final control device is DC (G05F1/625 takes precedence) - G05F 3/242: {with compensation for device parameters, e.g. channel width modulation, threshold voltage, processing, or external variations, e.g. temperature, loading, supply voltage} - H02M 3/158: including plural semiconductor devices as final control devices for a single load - G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) ## Abstract A tracking voltage generator, the latter including: a first transistor having a first leakage current and which is coupled with the flipped gate transistor so that a difference between a gate-source voltage (Vgs) of a flipped gate transistor and the first transistor is approximately equal to a bandgap voltage of a semiconductor material from which the tracking voltage generator is formed; an output node providing a tracking voltage which has a positive or negative temperature dependency based on the flipped gate transistor and the first transistor; and a second transistor connected to the output node and which has a second leakage current. A current reference includes: the tracking voltage generator; an amplifier to receive the tracking voltage and output an amplified signal; a control transistor to receive the amplified signal and conduct a reference current therethrough; and a control resistor connected in series with the control transistor. ## Claims ### Claim 1 A current reference comprising: a tracking voltage generator, the tracking voltage generator comprising: a flipped gate transistor; a first transistor, the first transistor having a first leakage current, wherein the first transistor is coupled with the flipped gate transistor in an arrangement wherein a difference between a gate-source voltage (Vgs) of the flipped gate transistor and the first transistor is approximately equal to a bandgap voltage of a semiconductor material from which the tracking voltage generator is formed; an output node configured to output a tracking voltage, the tracking voltage having a positive or negative temperature dependency based on the flipped gate transistor and the first transistor; and a second transistor connected to the output node, the second transistor having a second leakage current; an amplifier configured to receive the tracking voltage and to output an amplified signal; a control transistor configured to receive the amplified signal and to conduct a reference current therethrough; and a control resistor connected in series with the control transistor, the current reference thereby being configured so that a temperature dependency of the tracking voltage is substantially equal to a temperature dependency of a resistance of the control resistor, thereby maintaining the reference current at a constant value. ### Claim 2 (depends on 1) The current reference of claim 1, wherein the tracking voltage generator further comprises a boxing region configured to provide a voltage level at a drain terminal of the first transistor to maintain the first leakage current substantially equal to the second leakage current. ### Claim 3 (depends on 1) The current reference of claim 1, wherein the amplifier is further configured to receive a feedback voltage from a node located between the control transistor and the control resistor. ### Claim 4 (depends on 1) The current reference of claim 1, wherein the tracking voltage generator further comprises a current mirror region configured to provide a bias voltage to the amplifier. ### Claim 5 (depends on 1) The current reference of claim 1, wherein: the tracking voltage generator further comprises a startup and current generation region configured to generate a bias current, and the current reference is configured to provide an integer-ratio multiple of the bias current to the flipped gate transistor. ### Claim 6 (depends on 1) The current reference of claim 1, wherein the temperature dependency of the tracking voltage is dependent on a relative size of the flipped gate transistor with respect to the first transistor. ### Claim 7 (depends on 1) The current reference of claim 1, wherein the temperature dependency of the tracking voltage is dependent on a current density of the first transistor relative to a current density of the flipped gate transistor. ### Claim 8 A current reference comprising: a control resistor; a tracking voltage generator including: a first current source configured to supply a first current; a first transistor configured to receive the first current and have a first size and a flipped gate; a second current source and configured to provide a second current; and a second transistor configured to receive the second current and have a second size; wherein the tracking voltage generator is configured to provide, at an output node, a tracking voltage having a first temperature dependency over a temperature range based on a ratio of the second size to the first size; a third transistor coupled between the output node and ground, the third transistor having a grounded gate configuration and further being configured so that a voltage drop across the third transistor is substantially similar to a voltage drop across the second transistor which compensates for an effect on the tracking voltage; and an amplifier circuit configured to receive the tracking voltage and maintain a first voltage at a first terminal of the control resistor, the first voltage being substantially equal to the tracking voltage; and wherein the current reference thereby is configured to maintain a reference current through the control resistor at a constant value over the temperature range. ### Claim 9 (depends on 8) The current reference of claim 8, wherein the first temperature dependency of the tracking voltage is dependent on a relative size of the second transistor with respect to the first transistor. ### Claim 10 (depends on 8) The current reference of claim 8, wherein: the first transistor has a first leakage current; the second transistor has a second leakage current; and the tracking voltage generator further comprises a boxing region configured to provide a second voltage at a drain terminal of the first transistor, the second voltage having a level sufficient to maintain the first leakage current substantially equal to the second leakage current. ### Claim 11 (depends on 8) The current reference of claim 8, wherein the amplifier circuit is further configured to receive a feedback voltage from a node located between a control transistor and the control resistor. ### Claim 12 (depends on 8) The current reference of claim 8, wherein the tracking voltage generator further comprises a current mirror region configured to provide a bias voltage to the amplifier circuit. ### Claim 13 (depends on 8) The current reference of claim 8, wherein the tracking voltage generator further comprises: a startup and current generation region configured to generate the first current and provide the first current to the first transistor; and a current mirror region configured to receive a bias current and provide the first current as an integer multiple of the bias current. ### Claim 14 A current reference comprising: a control resistor; a tracking voltage generator including: a first transistor having a first size and a flipped gate; and a second transistor having a second size; wherein the tracking voltage generator is configured to provide, at an output node, a tracking voltage having a first temperature dependency over a temperature range based on a ratio of the second size to the first size; a boxing circuit configured to reduce a head-room penalty, the head-room penalty being a difference between a source voltage of the current reference and the tracking voltage; and a third transistor coupled between the output node and ground, the third transistor having a grounded gate configuration and further being configured so that a voltage drop across the third transistor is substantially similar to a voltage drop across the second transistor which compensates for an effect on the tracking voltage; and an amplifier circuit configured to receive the tracking voltage and maintain a first voltage at a first terminal of the control resistor, the first voltage being substantially equal to the tracking voltage; and wherein the current reference thereby is configured to maintain a reference current through the control resistor at a constant value over the temperature range. ### Claim 15 (depends on 14) The current reference of claim 14, wherein the first temperature dependency of the tracking voltage is dependent on a relative size of the second transistor with respect to the first transistor. ### Claim 16 (depends on 14) The current reference of claim 14, wherein: the first transistor has a first leakage current; the second transistor has a second leakage current; and the tracking voltage generator further comprises a boxing region configured to provide a second voltage at a drain terminal of the first transistor, the second voltage having a level sufficient to maintain the first leakage current substantially equal to the second leakage current. ### Claim 17 (depends on 14) The current reference of claim 14, wherein the amplifier circuit is further configured to receive a feedback voltage from a node located between a control transistor and the control resistor. ### Claim 18 (depends on 14) The current reference of claim 14, wherein the tracking voltage generator further comprises a current mirror region configured to provide a bias voltage to the amplifier circuit. ### Claim 19 (depends on 14) The current reference of claim 14, wherein the boxing circuit includes: a first level-shifter having an output configured to produce a decreasing level-shift of the source voltage; and a second level-shifter having an output configured to produce an increasing level-shift of a voltage level on a control input of the first level-shifter. ### Claim 20 (depends on 19) The current reference of claim 19, wherein: the first level-shifter includes: an NMOS transistor, a body terminal and source terminal of the NMOS transistor being coupled together; and the second level-shifter includes: a PMOS transistor, a body terminal and a source terminal of the PMOS transistor being coupled together.