CN114020088B - Band-gap reference voltage source suitable for low-current gain type NPN triode - Google Patents
Band-gap reference voltage source suitable for low-current gain type NPN triode Download PDFInfo
- Publication number
- CN114020088B CN114020088B CN202111287582.2A CN202111287582A CN114020088B CN 114020088 B CN114020088 B CN 114020088B CN 202111287582 A CN202111287582 A CN 202111287582A CN 114020088 B CN114020088 B CN 114020088B
- Authority
- CN
- China
- Prior art keywords
- triode
- mos tube
- electrode
- reference voltage
- current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F3/00—Non-retroactive systems for regulating electric variables by using an uncontrolled element, or an uncontrolled combination of elements, such element or such combination having self-regulating properties
- G05F3/02—Regulating voltage or current
- G05F3/08—Regulating voltage or current wherein the variable is dc
- G05F3/10—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics
- G05F3/16—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics being semiconductor devices
- G05F3/20—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics being semiconductor devices using diode- transistor combinations
- G05F3/26—Current mirrors
Abstract
The invention belongs to the technical field of reference sources, and particularly relates to a band-gap reference voltage source suitable for a low-current gain type NPN triode. According to the invention, an additional triode current gain coefficient Beta elimination circuit (Beta Cancellation) is added in the traditional Wildar type band gap reference voltage source framework, namely, the base current is recovered and then is fed back to the original framework, so that high-precision reference voltage irrelevant to the absolute value of the triode current gain coefficient Beta can be obtained, the traditional Wildar type reference voltage source framework is not sensitive to the triode current gain coefficient Beta, and meanwhile, the characteristics of loose input mismatch and noise requirements on the rear-stage operational amplifier are still maintained, and the method is also suitable for low power supply voltage application scenes.
Description
Technical Field
The invention belongs to the technical field of reference sources, and particularly relates to a band-gap reference voltage source suitable for a low-current gain type NPN triode.
Background
A band gap reference voltage source (Bandgap) is widely used in the chip field as a voltage reference due to its high precision characteristic. In a chip, designers often need to keep certain voltages within a set range through loop control, or need to generate high-precision current, or realize comparison and monitoring of certain voltage signals, which are all independent of an on-chip Bandgap reference voltage source (Bandgap). A band gap reference voltage source in a chip can often use a triode (BJT) as a key device, and the principle is that a triode base-emitter Voltage (VBE) with negative temperature characteristic and a base-emitter voltage difference (delta _ VBE) with positive temperature characteristic are utilized, and a high-precision voltage value independent of temperature is created by adding the base-emitter Voltage (VBE) with the base-emitter voltage difference (delta _ VBE). In the band-gap reference voltage source, the NPN type triode can obtain higher precision or better offset noise suppression by matching with different band-gap reference architectures due to a flexible three-terminal connection method, that is, unlike a parasitic PNP type triode, a collector (collector) can only be connected with a substrate (substrate), and only a traditional band-gap reference architecture can be built. For example, the NPN transistor may obtain a high-precision reference voltage by using a Brokaw-type bandgap reference architecture or a Widlar-type bandgap reference architecture to suppress offset and noise of a subsequent stage operational amplifier. However, due to cost considerations or process limitations, NPN transistors are often encountered in designs that do not have a high transistor current gain coefficient (Beta value). Some bandgap reference architectures require a Beta value greater than 20 or 50 or even higher to neglect the effect of the Beta variation on the final output reference voltage in the ideal formula, thereby limiting the application of high-precision reference architectures, such as the Wildar type. Meanwhile, as the power supply voltage required to operate is lower and lower, a part of bandgap reference structures, such as Brokaw type, cannot be satisfied. How to obtain a band-gap reference architecture which is high in precision and compatible with low-voltage operation under the condition of only a low-current gain type NPN triode is an urgent problem to be solved.
The Brokaw architecture utilizes the gain of a triode per se to reduce the requirements on the offset and the noise of a rear-stage operational amplifier, and because a base is output and biased by the operational amplifier, the finally output reference voltage is insensitive to the change of a triode current gain coefficient Beta, but the requirement of low working voltage cannot be applied to the high-precision reference design of low power supply voltage; the Wildar architecture has good characteristics suitable for low power supply voltage, has low requirements on post-stage operational amplifier imbalance and noise, but is limited by the characteristic that a triode current gain coefficient Beta is sensitive and cannot be adopted under the condition of a low-current gain type NPN triode. The Brokaw architecture (as shown in fig. 1) utilizes the gain of the transistor itself to reduce the requirements for the offset and noise of the rear-stage operational amplifier, and the base is biased by the operational amplifier output, so the finally output reference voltage is insensitive to the change of the transistor current gain coefficient Beta, but the requirement of the low operating voltage cannot be applied to the low-power-supply-voltage high-precision reference design, i.e. the power supply voltage VDD in fig. 1 at least needs to be higher than the reference output voltage VOUT by the Vgs voltage of M3 tube and the Vdsat voltage of M2 tube, and VDD also needs to be higher than the reference output voltage VOUT by the Vgs voltage of M1 tube and minus Q1 to ensure the Vbc voltage in the amplification region to work normally, compared with the situation that Wildar only needs VDD to be higher than the reference output voltage VOUT by one Vdsat, the difference of the typical architecture VDD to the requirements is about 0.8V, so the Brokaw architecture is not applicable to the low-voltage requirement; while the Wildar architecture (as shown in fig. 2) has a good characteristic suitable for low power supply voltage, and also has a low requirement on the post-stage operational amplifier mismatch and noise, but is limited by the characteristic that the current gain coefficient Beta of the transistor is sensitive and cannot be adopted under the condition of a low-current gain NPN transistor, that is, in fig. 2, the current flowing through R2 is Q1 collector current plus Q1 base current plus Q2 base current, and the current flowing through R3 is Q2 collector current plus Q3 base current, that is, if the current gain of the transistor is small, the influence of the base current is not negligible, the difference between the currents flowing through R2 and R3 is 1 part of base current, and the higher precision also has a strict requirement on the current flowing through Q3, so the traditional Wildar architecture is limited by the characteristic that the current gain coefficient Beta of the transistor cannot be adopted.
The prior art designs a low-voltage high-precision band-gap reference voltage source under the condition of only a low-current gain type NPN triode:
1. a conventional bandgap reference architecture, that is, a bandgap reference architecture of a parasitic PNP with a shorted base and collector or an NPN with a shorted base and collector, is adopted, as shown in fig. 3: because the collector and the base are short-circuited in the structure, the current gain coefficient Beta of the triode is not influenced in the formula. Meanwhile, the working voltage supported by the traditional band-gap reference is lower. The disadvantage is that because the amplifier is not provided with a gain, the input imbalance and equivalent input noise of the rear-stage operational amplifier have great influence on the finally output reference voltage, so that a large area or power consumption expense is needed for inhibiting the influence, and even a complex chopper method is adopted, certain noise ripple of the output voltage needs to be inhibited.
2. A current type bandgap reference architecture is adopted, that is, the base-emitter Voltage (VBE) and the base-emitter voltage difference (delta _ VBE) of the triode are converted into current signals, and then added to obtain a reference voltage, as shown in fig. 4. The advantage is that it can operate at very low supply voltages, even below the bandgap voltage VBG. The disadvantage is still high offset and noise requirements for the later stages of amplification.
Disclosure of Invention
According to the invention, an additional triode current gain coefficient Beta elimination circuit (Beta Cancellation) is added in the traditional Wildar type band gap reference voltage source framework, namely, the base current is recovered and then fed back to the original framework, so that high-precision reference voltage irrelevant to the absolute value of the triode current gain coefficient Beta can be obtained, the traditional Wildar type reference voltage source framework is not sensitive to the triode current gain coefficient Beta, meanwhile, the characteristics of loose input mismatch and noise requirements on the rear-stage operational amplifier are still kept, and the Wildar type band gap reference voltage source framework is also suitable for low power supply voltage application scenes.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the band-gap reference voltage source suitable for the low-current gain type NPN triode comprises a Wildar type band-gap reference voltage source and is characterized by further comprising a triode current gain coefficient Beta eliminating circuit, wherein the triode current gain coefficient Beta eliminating circuit obtains triode collector current from the Wildar type band-gap reference voltage source, base current with the same current gain coefficient Beta is recovered through an additional triode, and the current is used for a Wildar type band-gap reference voltage source framework to eliminate the influence of the triode current gain coefficient Beta on output reference voltage.
Further, the Wildar band gap reference voltage source comprises a first triode Q1, a second triode Q2, a third triode Q3, a first resistor R1, a second resistor R2, a third resistor R3 and a current source; the input of the current source is connected with a power supply VDD, the output of the current source is connected with the collector and the base of a first triode Q1 and the base of a second triode Q2 after passing through a second resistor R2, and the emitter of the first triode Q1 is grounded; the collector of the second triode Q2 is connected with the output of the current source after passing through the third resistor R3, and the emitter of the second triode Q2 is grounded after passing through the first resistor R1; the collector of the third triode Q3 is connected with the output of the current source, the base of the third triode Q3 is connected with the collector of the second triode Q2, and the emitter of the third triode Q3 is grounded;
the triode current gain coefficient Beta eliminating circuit comprises a fourth triode Q4, a fifth triode Q5, a first MOS (metal oxide semiconductor) tube M1, a second MOS tube M2, a third MOS tube M3, a fourth MOS tube M4 and a fifth MOS tube M5; the base electrode of the fourth triode Q4 is connected with the base electrode of the first triode Q1, the collector electrode of the fourth triode Q4 is connected with the drain electrode of the first MOS tube M1, and the emitting electrode of the fourth triode Q4 is grounded; the source electrode of the first MOS tube M1 is connected with a power supply VDD, and the grid electrode and the drain electrode of the first MOS tube M1 are interconnected; the source electrode of the second MOS tube M2 is connected with a power supply VDD, the grid electrode of the second MOS tube M2 is connected with the drain electrode of the first MOS tube M1, the drain electrode of the second MOS tube M2 is connected with the collector electrode of a fifth triode Q5, the base electrode of the fifth triode Q5 is connected with the source electrode of the fifth MOS tube M5, and the emitter electrode of the fifth triode Q5 is grounded; the source electrode of the fourth MOS tube M4 is connected with a power supply VDD, the grid electrode of the fourth MOS tube M4 is connected with the drain electrode of the third MOS tube M3, and the drain electrode of the fourth MOS tube M4 is connected with the collector electrode of the first triode Q1; the source electrode of the third MOS tube M3 is connected with a power supply VDD, and the grid electrode and the drain electrode of the third MOS tube M3 are interconnected; the drain electrode of the fifth MOS tube M5 is connected with the drain electrode of the third MOS tube M3, and the grid electrode of the fifth MOS tube M5 is connected with the drain electrode of the second MOS tube; and the connection point of the second resistor R2 and the third resistor R3 is the output end of the reference voltage source.
In the scheme of the invention, a triode current gain coefficient Beta elimination circuit (Beta Cancellation): a base current with the same current gain coefficient Beta is recovered by an additional triode through a mirrored collector current, and the current is used for a traditional Wildar band gap reference voltage source framework to eliminate the influence of the triode current gain coefficient Beta on output reference voltage.
The beneficial effects of the invention are as follows: according to the invention, an additional triode current gain coefficient Beta elimination circuit (Beta Cancellation) is added in the traditional Wildar type band gap reference voltage source framework, namely, the base current is recovered and then is fed back to the original framework, so that high-precision reference voltage irrelevant to the absolute value of the triode current gain coefficient Beta can be obtained, the traditional Wildar type reference voltage source framework is not sensitive to the triode current gain coefficient Beta, and meanwhile, the characteristics of loose input mismatch and noise requirements on the rear-stage operational amplifier are still maintained, and the method is also suitable for low power supply voltage application scenes.
Drawings
FIG. 1 is a generalized Brokaw-type bandgap reference architecture;
FIG. 2 is a generalized Wildar-type bandgap reference architecture;
FIG. 3 is a conventional bandgap reference architecture employing parasitic PNPs or NPNs;
FIG. 4 is a current mode bandgap reference architecture;
fig. 5 shows a general Wildar bandgap reference voltage modified architecture with a triode current gain coefficient Cancellation circuit (Beta Cancellation).
Detailed Description
The technical scheme of the invention is described in detail in the following with reference to the attached drawings:
fig. 5 is an optimization of the general Wildar-type bandgap reference voltage architecture in fig. 2, that is, a general Wildar-type bandgap reference voltage improved architecture with a triode current gain coefficient Beta Cancellation circuit (Beta Cancellation). The basic framework of the Wildar type band gap reference voltage is shown in the figure, the extraction of collector current, the calculation of a triode current gain coefficient Beta and the elimination of the sensitivity of the triode current gain coefficient Beta in the traditional Wildar type framework are realized by innovatively adding Q4-Q5 and M1-M5. Finally, the fact that a traditional Wildar band-gap reference voltage source framework is insensitive to a triode current gain coefficient Beta is achieved.
The specific working principle is as follows: q4 and Q1 are identical NPN type triodes, and the same base and emitter connection ensures that Q4 and Q1 have the same collector current, namely the extraction of the collector current is realized. The collector current is input to the Q5 through a current mirror consisting of M1 and M2, the collector and the base of the Q5 ensure that the Q5 works in an amplification region through the feedback of the M5, namely the Q5 and the Q4 have the same collector current, and because the Q5 and the Q1-Q4 work in the same working region, namely the amplification region and the current magnitude is the same, the Q5 and the Q1-Q4 have the same triode current gain coefficient Beta, so the base current provided by the M5 to the Q5 is basically the same as the base current of the Q1-Q4. M3-M4 copies the base current through another current mirror to cancel the non-ideal factor part of Beta sensitivity in the original conventional Wildar-type bandgap reference voltage framework on the right side of FIG. 5, i.e. the R2 flowing current in the conventional Wildar framework is the sum of the Q1 collector current, the Q1 base current and the Q2 base current, and the R3 flowing current to be matched is only the sum of the Q2 collector current and the Q3 base current, so that deviation exists and the final reference voltage output is sensitive to the triode current gain coefficient Beta in the process. It should be noted that M4 needs to be twice M3 because the additional collector extraction circuit Q4 is also connected to the base of Q1, i.e. Q4 base current will also flow through R2, so 2 parts of base current needs to be compensated.
Claims (1)
1. A band-gap reference voltage source suitable for a low-current gain type NPN triode comprises a Wildar type band-gap reference voltage source and is characterized by further comprising a triode current gain coefficient Beta eliminating circuit, wherein the triode current gain coefficient Beta eliminating circuit obtains triode collector current from the Wildar type band-gap reference voltage source, base current with the same current gain coefficient Beta is recovered through an additional triode, and the current is used for a Wildar type band-gap reference voltage source framework to eliminate the influence of the triode current gain coefficient Beta on output reference voltage;
the Wildar band gap reference voltage source comprises a first triode Q1, a second triode Q2, a third triode Q3, a first resistor R1, a second resistor R2, a third resistor R3 and a current source; the input of the current source is connected with a power supply VDD, the output of the current source is connected with the collector and the base of a first triode Q1 and the base of a second triode Q2 after passing through a second resistor R2, and the emitter of the first triode Q1 is grounded; the collector of the second triode Q2 is connected with the output of the current source after passing through the third resistor R3, and the emitter of the second triode Q2 is grounded after passing through the first resistor R1; the collector of the third triode Q3 is connected with the output of the current source, the base of the third triode Q3 is connected with the collector of the second triode Q2, and the emitter of the third triode Q3 is grounded;
the triode current gain coefficient Beta eliminating circuit comprises a fourth triode Q4, a fifth triode Q5, a first MOS (metal oxide semiconductor) tube M1, a second MOS tube M2, a third MOS tube M3, a fourth MOS tube M4 and a fifth MOS tube M5; the base electrode of the fourth triode Q4 is connected with the base electrode of the first triode Q1, the collector electrode of the fourth triode Q4 is connected with the drain electrode of the first MOS tube M1, and the emitting electrode of the fourth triode Q4 is grounded; the source electrode of the first MOS tube M1 is connected with a power supply VDD, and the grid electrode and the drain electrode of the first MOS tube M1 are interconnected; the source electrode of the second MOS tube M2 is connected with a power supply VDD, the grid electrode of the second MOS tube M2 is connected with the drain electrode of the first MOS tube M1, the drain electrode of the second MOS tube M2 is connected with the collector electrode of a fifth triode Q5, the base electrode of the fifth triode Q5 is connected with the source electrode of the fifth MOS tube M5, and the emitter electrode of the fifth triode Q5 is grounded; the source electrode of the fourth MOS tube M4 is connected with a power supply VDD, the grid electrode of the fourth MOS tube M4 is connected with the drain electrode of the third MOS tube M3, and the drain electrode of the fourth MOS tube M4 is connected with the collector electrode of the first triode Q1; the source electrode of the third MOS tube M3 is connected with a power supply VDD, and the grid electrode and the drain electrode of the third MOS tube M3 are interconnected; the drain electrode of the fifth MOS tube M5 is connected with the drain electrode of the third MOS tube M3, and the grid electrode of the fifth MOS tube M5 is connected with the drain electrode of the second MOS tube; and the connection point of the second resistor R2 and the third resistor R3 is the output end of the reference voltage source.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111287582.2A CN114020088B (en) | 2021-11-02 | 2021-11-02 | Band-gap reference voltage source suitable for low-current gain type NPN triode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111287582.2A CN114020088B (en) | 2021-11-02 | 2021-11-02 | Band-gap reference voltage source suitable for low-current gain type NPN triode |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114020088A CN114020088A (en) | 2022-02-08 |
| CN114020088B true CN114020088B (en) | 2022-12-02 |
Family
ID=80060269
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111287582.2A Active CN114020088B (en) | 2021-11-02 | 2021-11-02 | Band-gap reference voltage source suitable for low-current gain type NPN triode |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114020088B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114020089B (en) * | 2021-11-02 | 2022-12-06 | 苏州中科华矽半导体科技有限公司 | Band-gap reference voltage source suitable for low-current gain type NPN triode |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102193574A (en) * | 2011-05-11 | 2011-09-21 | 电子科技大学 | Band-gap reference voltage source with high-order curvature compensation |
| WO2017049840A1 (en) * | 2015-09-21 | 2017-03-30 | 东南大学 | Band-gap reference voltage source with high power supply rejection ratio |
| CN109324655A (en) * | 2018-11-15 | 2019-02-12 | 成都嘉纳海威科技有限责任公司 | A kind of High Precision Exponential temperature-compensating CMOS band-gap reference circuit |
| CN109471486A (en) * | 2019-01-14 | 2019-03-15 | 电子科技大学 | A kind of low noise bandgap references circuit reducing offset influence |
| CN114020089A (en) * | 2021-11-02 | 2022-02-08 | 苏州华矽共创信息技术合伙企业(有限合伙) | Band-gap reference voltage source suitable for low-current gain type NPN triode |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7902912B2 (en) * | 2008-03-25 | 2011-03-08 | Analog Devices, Inc. | Bias current generator |
| US11349444B2 (en) * | 2019-07-30 | 2022-05-31 | Sumitomo Electric Industries, Ltd. | Transimpedance amplifier circuit |
-
2021
- 2021-11-02 CN CN202111287582.2A patent/CN114020088B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102193574A (en) * | 2011-05-11 | 2011-09-21 | 电子科技大学 | Band-gap reference voltage source with high-order curvature compensation |
| WO2017049840A1 (en) * | 2015-09-21 | 2017-03-30 | 东南大学 | Band-gap reference voltage source with high power supply rejection ratio |
| CN109324655A (en) * | 2018-11-15 | 2019-02-12 | 成都嘉纳海威科技有限责任公司 | A kind of High Precision Exponential temperature-compensating CMOS band-gap reference circuit |
| CN109471486A (en) * | 2019-01-14 | 2019-03-15 | 电子科技大学 | A kind of low noise bandgap references circuit reducing offset influence |
| CN114020089A (en) * | 2021-11-02 | 2022-02-08 | 苏州华矽共创信息技术合伙企业(有限合伙) | Band-gap reference voltage source suitable for low-current gain type NPN triode |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114020088A (en) | 2022-02-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8482342B2 (en) | Circuit for generating a reference voltage with compensation of the offset voltage | |
| CN106959723A (en) | A kind of bandgap voltage reference of wide input range high PSRR | |
| CN108351662B (en) | Bandgap reference circuit with curvature compensation | |
| CN113934249B (en) | Band-gap reference voltage source suitable for low-current gain type NPN triode | |
| TWI418968B (en) | Circuit and method for generating reference voltage and reference current | |
| Ng et al. | A Sub-1 V, 26$\mu $ W, Low-Output-Impedance CMOS Bandgap Reference With a Low Dropout or Source Follower Mode | |
| CN108710401B (en) | Band-gap reference voltage source with high precision and large driving current | |
| US7466201B1 (en) | Class AB output stage and method for providing wide supply voltage range | |
| CN108536210B (en) | Smooth temperature compensation band gap reference source circuit | |
| CN114020088B (en) | Band-gap reference voltage source suitable for low-current gain type NPN triode | |
| CN114020089B (en) | Band-gap reference voltage source suitable for low-current gain type NPN triode | |
| CN113885634B (en) | Band-gap reference voltage source suitable for low-current gain type NPN triode | |
| CN111293876B (en) | Linear circuit of charge pump | |
| US20230324941A1 (en) | Bandgap current reference | |
| CN219016862U (en) | Exponential temperature compensation band-gap reference circuit without operational amplifier | |
| CN111879999B (en) | Low-temperature coefficient rapid voltage detection circuit | |
| CN111752325A (en) | High-precision linear voltage stabilizing circuit | |
| CN112596576A (en) | Band gap reference circuit | |
| CN105630063A (en) | Reference power supply generating circuit | |
| JP3322553B2 (en) | Temperature detection circuit and test method thereof | |
| CN212484194U (en) | CMOS voltage reference source | |
| JP7224387B2 (en) | amplifier circuit | |
| CN114706442B (en) | Low-power consumption band-gap reference circuit | |
| US20240103558A1 (en) | Gain and temperature tolerant bandgap voltage reference | |
| Zhang et al. | A BJT-Based Temperature Sensor in 40-nm CMOS With±0.8° C (3σ) Untrimmed Inaccuracy |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| TA01 | Transfer of patent application right |
Effective date of registration: 20220927 Address after: 215000-5-501, building 05, 78 Keling Road, science and Technology City, Suzhou high tech Zone, Jiangsu Province Applicant after: Suzhou Zhongkehua silicon semiconductor technology Co.,Ltd. Address before: 215000-5-501, building 05, 78 Keling Road, science and Technology City, Suzhou high tech Zone, Jiangsu Province Applicant before: Suzhou Huasi Gongchuang information technology partnership (L.P.) |
|
| TA01 | Transfer of patent application right | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |