CN213934663U - Current trimming circuit for band-gap reference - Google Patents
Current trimming circuit for band-gap reference Download PDFInfo
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- CN213934663U CN213934663U CN202022846268.0U CN202022846268U CN213934663U CN 213934663 U CN213934663 U CN 213934663U CN 202022846268 U CN202022846268 U CN 202022846268U CN 213934663 U CN213934663 U CN 213934663U
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Abstract
The utility model discloses a current trimming circuit for band gap benchmark relates to integrated circuit technical field, the parallelly connected source electrode and the drain electrode at current mirror MOSFET of current trimming circuit, current trimming circuit includes the parallelly connected branch road of multiunit, every group branch road structure is the same includes switch and MOSFET pipe, the source electrode of MOSFET pipe is connected to the first end of switch, the second end of each switch links to each other in proper order, the drain electrode of each MOSFET pipe links to each other in proper order, the grid of each MOSFET pipe inserts the bias voltage the same with current mirror MOSFET's grid, current mirror MOSFET's source electrode connecting power, current mirror MOSFET's drain electrode passes through resistance ground connection, the switch is used for adjusting the trimming current of each branch road, and then adjusting resistance's output voltage. The area of a chip is greatly reduced by trimming the MOSFET, the switch trimming is adopted to realize the non-frequency limitation trimming, and trimming values are increased or reduced according to requirements.
Description
Technical Field
The utility model belongs to the technical field of the integrated circuit technique and specifically relates to a current trimming circuit for band gap reference.
Background
The bandgap reference circuit can output a reference voltage that does not vary with supply voltage and temperature variations. The sensitivity of the output reference voltage to temperature variation is an important technical parameter of the bandgap reference circuit, namely, the temperature coefficient.
The band-gap reference circuit which is designed reasonably theoretically has good temperature coefficient and linearity. However, due to the many process steps in the integrated circuit manufacturing process, errors inevitably occur in each device used in the circuit. The accumulation of these process errors eventually results in the output voltage value, temperature coefficient and other parameters not meeting the design requirements.
To address this problem, trimming circuitry is often necessary in bandgap reference designs. The parameters of the chip are corrected and adjusted by reasonably adjusting the trimming circuit, and finally, all parameters of the output reference voltage of the chip which is actually produced meet the design requirements.
As shown in fig. 1, the conventional trimming circuit usually trims the resistor, and occupies a large chip area. And the traditional trimming circuit is used for trimming by a multi-purpose fuse, which causes the trimming process to be irreversible and can be trimmed only once. When the output voltage parameter is unstable due to the change of working environment and overlong service time after one-time trimming is finished, the fuse trimming circuit cannot correct the output voltage of the circuit again.
SUMMERY OF THE UTILITY MODEL
The invention provides a current trimming circuit for band-gap reference, aiming at the problems and the technical requirements, the invention changes the traditional resistance trimming into the trimming of an MOSFET, greatly reduces the chip area, changes the fuse trimming into the switch trimming, thereby realizing the non-frequency-limited trimming and increasing or reducing the trimming value according to the requirements.
The technical scheme of the utility model as follows:
the utility model provides a current trimming circuit for band gap reference, the current trimming circuit connects in parallel at the source electrode and the drain electrode of current mirror MOSFET, the current trimming circuit includes the parallelly connected branch road of multiunit, every group branch road structure is the same, all include switch and MOSFET pipe, the source electrode of MOSFET pipe is connected to the first end of switch, the second end of each switch links to each other in proper order, and the common terminal connection current mirror MOSFET's of second end source electrode, the drain electrode of each MOSFET pipe links to each other in proper order, and the drain electrode common terminal connection current mirror MOSFET's of MOSFET pipe drain electrode, the grid of each MOSFET pipe all inserts the same bias voltage with current mirror MOSFET's grid, current mirror MOSFET's source electrode still connects the power with current trimming circuit's common terminal, the common terminal of current mirror MOSFET's drain electrode and current trimming circuit still passes through resistance ground connection, the switch is used for adjusting the trimming current of each branch road of current trimming circuit, and then the output voltage of adjustment resistance.
The further technical scheme is that the channel length of the MOSFET is the same as that of the current mirror MOSFET, and the channel width of the MOSFET of the Kth branch is 2K-1And n ', wherein n' represents the channel width of the MOSFET tube of the first branch and is taken according to the minimum resolution current of the trimming current.
The further technical scheme is that a switch is manufactured through an outgoing pad port.
The utility model has the beneficial technical effects that:
the current trimming circuit is completely compatible with a common BCD process, adopts a switch trimming mode, avoids one-time trimming and irreversible trimming of fuse trimming, can movably realize non-frequency limitation trimming, and can increase or decrease trimming values according to requirements; because the trimming circuit is used for current trimming instead of traditional resistor trimming, a resistor array with a large use area is avoided, and only a plurality of MOSFET tubes with small occupied area are needed, so that the chip area is greatly reduced.
Drawings
Fig. 1 is a voltage-based trimming circuit with a conventional resistor-fuse series structure and an operation thereof.
Fig. 2 is a current-mode trimming circuit with a switch-MOSFET parallel structure and an operation schematic diagram thereof.
Detailed Description
The following describes the embodiments of the present invention with reference to the accompanying drawings.
In order to eliminate the deviation of the output voltage caused by errors generated in the manufacturing process of the integrated circuit, a trimming circuit can be connected in series in an output branch of the bandgap reference circuit, and the voltage drop of the trimming circuit is adjusted to adjust the output voltage, so that the influence caused by the process errors is eliminated.
As shown in FIG. 1, a current mirror MOSFET replicates a zero temperature coefficient current through a bias voltage provided by a bandgap reference bulk circuit, which is applied to a resistorR to produce a temperature independent output voltage at the output. The specific circuit structure of the trimming circuit is a part in a dashed line frame in fig. 1, and is composed of K pairs of units in which resistors and fuses are connected in parallel, wherein K is 0,1,2 … …. The minimum value of the resistance value of the resistor is n, and the value of n can be determined by the minimum step length of trimming. The resistance values of the parallel units are arranged according to K-bit binary codes from small to large. When the corresponding fuse is fused, the resistor takes effect, the voltage drop of the corresponding resistance value is increased at the output end, and the corresponding binary code is '1'; if the fuse is not fused, the resistor is short-circuited, the output voltage drop is not increased, and the binary code is '0'. Therefore, the resistance of the trimming circuit can be adjusted to be 0-2 through the fusing code of the fuseKn, the output voltage is adjusted within the range of 0- (2)K+1-1)nI1In which I1Is a fixed current.
Since the fuse is used in this trimming method, the fuse cannot be connected after being melted, and therefore the trimming is a one-time trimming and is irreversible. In addition, the voltage trimming mode needs a larger resistor, and occupies a larger chip area.
The application discloses a current trimming circuit for band-gap reference, as shown in fig. 2, the current trimming circuit is connected in parallel with the source and the drain of a current mirror MOSFET, the current mirror MOSFET copies zero temperature coefficient current through bias voltage provided by a main circuit of the band-gap reference, and the current is applied to a resistor R, so that output voltage irrelevant to temperature is generated at the output end.
The specific circuit structure of the trimming circuit is a part in a dotted line frame in fig. 2, and comprises K groups of parallel branches, wherein each group of branches has the same structure and comprises a switch SKAnd MOSFET, switch SKIs connected with the source electrode of the MOSFET, each switch SKThe second ends of the first and second terminals are connected in sequence, and the common end of the second ends is connected with the source electrode of the current mirror MOSFET. Optionally, a switch is directly manufactured through an outgoing pad port in the integrated circuit design; the MOSFET adopts a P-type MOSFET. The drain electrodes of the MOSFET tubes are connected in sequence, the common end of the drain electrodes of the MOSFET tubes is connected with the drain electrode of the current mirror MOSFET, the grid electrode of each MOSFET tube is connected with the bias voltage same as that of the grid electrode of the current mirror MOSFET, and the channel length of the MOSFET tubeThe degree L is the same as the channel length of the current mirror MOSFET, the channel width W of the MOSFET tube of the first branch of the current trimming circuit is n ', the channel width W of the MOSFET tube of the second branch is 2n ', the channel width W of the MOSFET tube of the third branch is 4n ', and the channel width W of the MOSFET tube of the Kth branch is 2K-1n', where n is a value according to the minimum resolution current of the trimming current, K is 1,2,3 … …, and the value is determined according to the specific process deviation limit, and is generally between 3 and 6. The source electrode of the current mirror MOSFET and the common end of the current trimming circuit are also connected with a power supply VCC, the drain electrode of the current mirror MOSFET and the common end of the current trimming circuit are also grounded through a resistor R, and a switch SKThe current trimming circuit is used for adjusting the trimming current of each branch of the current trimming circuit, and further adjusting the output voltage of the resistor R, thereby eliminating the influence caused by process errors.
When the switch SKWhen closed, the corresponding branch generates current, for example, the trimming current of the first branch of the current trimming circuit is I, the trimming current of the second branch is 2I, the trimming current of the third branch is 3I, and so on, the trimming current of the kth branch is 2K-1And I, after the resistor R is applied to the resistor R, a corresponding voltage drop is increased at the output end. When the switch SKWhen the circuit is disconnected, the corresponding branch circuit is open, no current exists in the branch circuit, and the voltage drop is not increased at the output end. Thus, the current flowing through the resistor R can be controlled by the switch to be 0- (2)K-1)I2Regulation in the range in which I2Is the minimum trim current.
The trimming mode can be repeatedly opened or closed according to needs due to the use of the switch, so that the trimming process can be repeatedly carried out without the limitation of trimming times. In integrated circuit chip designs, switches can be fabricated directly through a PAD out Port (PAD). In addition, due to the current type trimming method, the trimming device is an MOSFET, so that the resistor with larger occupied area is avoided, and the chip area of the trimming circuit is greatly reduced.
What has been described above is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiments. It is to be understood that other modifications and variations directly derivable or suggested by those skilled in the art without departing from the spirit and scope of the present invention are to be considered as included within the scope of the present invention.
Claims (3)
1. A current trimming circuit for band-gap reference is characterized in that the current trimming circuit is connected in parallel with a source electrode and a drain electrode of a current mirror MOSFET, the current trimming circuit comprises a plurality of groups of branches which are connected in parallel, each group of branches has the same structure and comprises a switch and a MOSFET, a first end of the switch is connected with the source electrode of the MOSFET, a second end of each switch is connected in sequence, a common end of the second ends is connected with the source electrode of the current mirror MOSFET, drain electrodes of the MOSFET are connected in sequence, a common end of the drain electrodes of the MOSFET is connected with the drain electrode of the current mirror MOSFET, a grid electrode of the MOSFET is connected with a bias voltage which is the same as that of the grid electrode of the current mirror MOSFET, a source electrode of the current mirror MOSFET and a common end of the current trimming circuit are also connected with a power supply, and a common end of the drain electrode of the current mirror MOSFET and the common end of the current trimming circuit are also grounded through a resistor, the switch is used for adjusting the trimming current of each branch of the current trimming circuit, and further adjusting the output voltage of the resistor.
2. The current trimming circuit for bandgap reference according to claim 1, wherein the channel length of the MOSFET transistor is the same as the channel length of the current mirror MOSFET, and the channel width of the MOSFET transistor of the kth branch is 2K-1And n ', wherein n' represents the channel width of the MOSFET of the first branch circuit, and the value is taken according to the minimum resolution current of the trimming current.
3. A current trimming circuit for a bandgap reference according to claim 1 or claim 2, wherein the switch is made through a pad out port.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022846268.0U CN213934663U (en) | 2020-12-01 | 2020-12-01 | Current trimming circuit for band-gap reference |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202022846268.0U CN213934663U (en) | 2020-12-01 | 2020-12-01 | Current trimming circuit for band-gap reference |
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| CN213934663U true CN213934663U (en) | 2021-08-10 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114253337A (en) * | 2021-12-08 | 2022-03-29 | 电子科技大学 | Band-gap reference circuit integrating over-temperature protection and resistance trimming protection functions |
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- 2020-12-01 CN CN202022846268.0U patent/CN213934663U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114253337A (en) * | 2021-12-08 | 2022-03-29 | 电子科技大学 | Band-gap reference circuit integrating over-temperature protection and resistance trimming protection functions |
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Effective date of registration: 20221031 Address after: Room 1306, 13th Floor, Yanchuang Building, No. 1 Yinbai Road, Liyuan Development Zone, Binhu District, Wuxi City, Jiangsu Province 214000 Patentee after: Wuxi Zhongxiang Technology Co.,Ltd. Address before: 214153 Qianlotus Road No. 1, Wuxi City, Jiangsu Province Patentee before: JIANGSU VOCATIONAL College OF INFORMATION TECHNOLOGY |
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