CN202455320U - RC (resistor-capacitor) filter correction circuit - Google Patents
RC (resistor-capacitor) filter correction circuit Download PDFInfo
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- CN202455320U CN202455320U CN201120571778XU CN201120571778U CN202455320U CN 202455320 U CN202455320 U CN 202455320U CN 201120571778X U CN201120571778X U CN 201120571778XU CN 201120571778 U CN201120571778 U CN 201120571778U CN 202455320 U CN202455320 U CN 202455320U
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Abstract
The utility model discloses an RC (resistor-capacitor) filter correction circuit, which is used for correcting an RC filter, and is characterized in that one of two input ends of a comparator is arranged between a first resistor and a variable capacitor, and the other input end of the comparator is connected into a transformation circuit; and the circuit correction is realized by utilizing the RC charging principle, so that an operation amplifier is omitted on the premise without influencing the precision, the correction circuit is simplified, the power consumption is reduced, the size is reduced, and simultaneously the non-ideal factors of the operation amplifier such as direct-current imbalance can be prevented from producing negative influence on the correction precision.
Description
Technical field
The utility model relates to a kind of correcting circuit, especially relates to a kind of RC filter correction circuit.
Background technology
In field of analog integrated circuit, RC filter, especially RC active filter are because its better linearity degree has simply obtained using widely with realization.In the CMOS manufacturing process, all there are bigger deviation in resistance and electric capacity in modern times.According to the integrated circuit fabrication process of present main flow, R and C have respectively ± 20%, ± more than 10% with the variation of technology.This system that great majority are used the RC filter is unacceptable.Therefore, must proofread and correct to RC.Tradition RC proofreaies and correct and adopts the clock alternative, promptly utilizes clock frequency relevant with RC of RC oscillator realization in the sheet, realizes proofreading and correct through relevant clock comparison circuit then.This technology circuit is complicated, and the vibration precision effect correction effect of RC oscillator.
The patent No. is the Chinese patent of 200910056373.X, and a kind of new the RC correcting circuit and the method for displaying are as shown in Figure 1, because the feedback effect of operational amplifier, the voltage that makes the voltage of A node equal the B node equals VDD/2.Therefore, the charging current to C < 4:0>switched capacitor array equals (VDD-Vref)/R=VDD/ (2R).The last step voltage of capacitor array equaled I*Tint/C=VDD*Tint/ (2R*C) when charge cycle finished; The value of adjustment capacitor array makes that the voltage of two ports of comparator input is approximate identical; That is: VDD*Tint/ (2R*C)=Vref=VDD/2; Then R*C=Tint=1/CLKint, so RC product does not receive process variations influence.
This technological shortcoming is that circuit power consumption is high and volume is big, and simultaneously, the non-ideal factor of electronic device such as operational amplifier can have a negative impact to the precision of proofreading and correct.
The utility model content
The technical problem underlying that the utility model will solve is; A kind of RC filter correction circuit is provided; It uses less electronic device, and circuit realizes that power consumption reduces, volume reduces, and has reduced the negative effect that the non-ideal factor because of electronic device produces the precision of proofreading and correct.
For solving the problems of the technologies described above; The utility model provides a kind of RC filter correction circuit, and said RC filter circuit comprises RC filter and correcting circuit, and said RC filter comprises first resistance and the variable capacitance of serial connection; Said first resistance connects supply voltage, said variable capacitance ground connection; Said correcting circuit comprises comparator, controller and generating circuit from reference voltage; The input that of said comparator is used to obtain charging voltage is connected between first resistance and the variable capacitance, and another input that is used to obtain contrast potential is connected the output of generating circuit from reference voltage; The output that said comparator is used for the output voltage comparative result is connected with the input of controller, and the output that said controller is used to export regulating command connects said variable capacitance.
Said generating circuit from reference voltage is a resistor voltage divider circuit.
Said resistor voltage divider circuit comprises the resistance of two series connection, and an input of comparator is connected between two resistance; One termination power voltage of said resistor voltage divider circuit, other end ground connection.
The resistance of the resistance of said two series connection equates.
Said comparator is connected the said input between the variable capacitance and first resistance, between this input and comparator, also is serially connected with a low pass filter.
Said variable capacitance is a switched capacitor array.
Said RC filter comprises that also being located at being used between the variable capacitance and first resistance controls first switch that variable capacitance charges.
Said correcting circuit comprises that also be used to parallelly connected with variable capacitance control the second switch of variable capacitance discharge.
The beneficial effect of the utility model is: through two inputs with comparator, one is connected between first resistance and the variable capacitance, and another is connected in the generating circuit from reference voltage; The circuit that has utilized the RC charging principle to realize is proofreaied and correct; Under the prerequisite that does not influence precision, save operational amplifier, simplify correcting circuit, reduce power consumption; Reduce volume, avoided non-ideal factor such as the DC maladjustment etc. of operational amplifier that the precision of proofreading and correct is had a negative impact simultaneously.
Description of drawings
Fig. 1 is existing RC correcting circuit sketch map;
Fig. 2 is the utility model correcting circuit sketch map;
Fig. 3 is the clock signal clk dis of the utility model correcting circuit and the sequential chart of CLKint.
Embodiment
Combine accompanying drawing that the utility model is done further explain through embodiment below.
Like Fig. 2, shown in Figure 3, a kind of RC filter correction circuit combines the RC charging process with the RC alignment technique, promptly comprise RC filter and correcting circuit.Concrete, the RC filter comprises first resistance 3 (R), first switch 4 and the variable capacitance of series connection successively; The RC filter is provided with a termination power voltage VDD of first resistance 3, the other end (leaning on variable capacitance one end) ground connection; First switch 4 is used to control the variable capacitance charging.Said correcting circuit comprises that comparator, controller (Logic Control), generating circuit from reference voltage reach the second switch 5 that the variable capacitance discharge is controlled in be used to parallelly connected with variable capacitance; Concrete, voltage generation circuit is equivalence second resistance 1 (R1), the 3rd resistance 2 (R2) of two series connection, and two aforesaid supply voltages of resistance one termination, other end ground connection; Two inputs of comparator, one is connected the charging voltage V that obtains variable capacitance between first switch 4 and the variable capacitance
Int, another output (between second resistance 1 and the 3rd resistance 2) that is connected generating circuit from reference voltage obtains contrast potential V
RefAfter connecting 4 pairs of variable capacitance chargings of first switch, the charging voltage V that comparator obtains two inputs
IntWith contrast potential V
RefCompare, and comparing result is sent to said controller, controller is regulated variable capacitance according to the comparative result of comparator.
Concrete, variable capacitance adopts switched capacitor array 6.
During enforcement, like Fig. 2, shown in 3, the clock signal clk int of first switch 4, the clock signal clk dis of second switch 5, the clock signal of controller is CLK logic; These clock signals all derive from the frequency of oscillation of crystal oscillator, have very high precision.Switched capacitor array (variable capacitance), embodiment as shown in the figure, it is 5bit, control bit is from register.
During enforcement, said generating circuit from reference voltage can adopt other contrast potential V
RefProduce circuit,, be not limited to the mode of electric resistance partial pressure like external power supply etc.When adopting the mode of parallel resistance dividing potential drop, the 3rd resistance 2 also is not limited to and equals second resistance 1.
During enforcement, the utility model also can be applied to be not limited to the type of RC filter in other system and chip that has the RC filter.
During enforcement, the utility model also can be applied in other system and chip that need proofread and correct RC time constant on the sheet.
During enforcement, through being connected between the variable capacitance and first resistance 3, obtain charging voltage V like an input of aforementioned comparator
Int,, this input can be connected in series a low pass filter earlier before inserting, and low pass filter is to obtaining charging voltage V
IntCarry out Filtering Processing, realize the purpose of filtering burr, raising precision.
A kind of RC filter correction circuit, it combines the RC charging process with the RC alignment technique.Two inputs of comparator obtain the charging voltage V of variable capacitance respectively
IntContrast potential V with the generating circuit from reference voltage output
RefThe job step of this circuit is:
The first step was carried out the closed action of second switch 5, and variable capacitance is discharged;
In second step, closed first switch 4 charges to variable capacitance;
In the 3rd step, break off first switch 4, comparator contrast potential V
RefWith charging voltage V
IntVoltage peak compare;
In the 4th step, comparator is sent to controller with comparative result, and variable capacitance is heightened or turned down to controller according to the comparative result of comparator;
In the 5th step, get back to the first step, up to V
Ref＞V
Int, stop flow process.
During enforcement, obtain the charging voltage V of variable capacitance at said comparator
IntBefore, can be to the charging voltage V that it obtained
IntCarry out Filtering Processing earlier, with filtering burr, raising precision.The device of realizing Filtering Processing can be a low pass filter.
This step is concrete, in conjunction with Fig. 2,3 illustrated embodiments, can know the clock signal clk int of first switch 4, the clock signal clk dis of second switch 5, and the clock signal of controller is CLK logic; Switched capacitor array 6 (belonging to variable capacitance), control bit are 5bit.Be 1/8 duty ratio among CLKint and the CLKdis figure.
The explanation of concrete sequential, like Fig. 3:
When CLKdis=1, CLKint=0, to switched capacitor array 6 discharges;
When CLKdis=0, CLKint=1, switched capacitor array 6 is charged;
When CLKdis=0, CLKint=0, charging stops, charging voltage V
IntKeep; In Tc, when treating CLKlogic=1, controller circuitry obtains the output result (0 or 1) of comparator, supposes that the output result is 0, and then trimming process is proceeded; When next CLKdis=1, CLKint=0, switched capacitor array 6 discharges, according to the output result 0 of comparator, controller circuitry changes the array capacitor value of switched capacitor array 6 at the trailing edge of CLKdis.
After aforesaid state takes place in regular turn, promptly accomplished a wherein small step trimming process.Finally correcting result accurately also need be carried out repetition to these steps, up to comparator contrast potential V
RefGreater than charging voltage V
Int, comparator output 1, this moment, correction stopped, output C<4:0>Signal.
The principle of this correction is: suppose that the 3rd resistance 2 resistances equal second resistance, 1 resistance, then V
Ref=VDD/2.At CLKint is between high period, can get according to the charging principle of RC circuit: V
Int=VDD{1-e^ [T/ (RC
Tuning)], through regulating the size of variable capacitance, make V
Int=V
RefThereby, obtain R*C
Tuning=T*ln2=1n2/CLKint.CLKint derives from crystal oscillator, has very high precision, does not receive the influence of process deviation, makes R*C
TuningValue be definite value, accomplish to proofread and correct.(C wherein
TuningBe the capacitance of switched capacitor array 6, R is first resistance, 3 resistances, and VDD is a supply voltage)
The electric capacity of RC active filter on the sheet is designed to the switched capacitor array of 5bit equally, register controlled position Out < 4:0>is outputed to RC filter on the sheet, just reached the purpose that the frequency of RC filter on the sheet is proofreaied and correct.
When implementing, the control bit of switched capacitor array is not limited to 5bit.
When implementing, realize sequential like Fig. 3, the duty ratio of CLKint and CLKdis clock is not limited to 1/8.
The shortcoming of prior art is the contrast potential V of correcting circuit
RefGeneration needs an extra operational amplifier, consumes certain power consumption and area.Simultaneously, the non-ideal factor of operational amplifier such as DC maladjustment etc. have a negative impact to the precision of proofreading and correct.The utility model saves operational amplifier under the prerequisite that does not influence precision, simplify correcting circuit, reduces power consumption, reduces area.The utility model is feasible through emulation and testing authentication, especially can good operation under 0.18um and 0.13um CMOS technology 1.2v supply voltage.
Above content is the further explain that combines concrete execution mode that the utility model is done, and can not assert that the practical implementation of the utility model is confined to these explanations.For the those of ordinary skill of technical field under the utility model, under the prerequisite that does not break away from the utility model design, can also make some simple deduction or replace, all should be regarded as belonging to the protection range of the utility model.
Claims (9)
1. a RC filter correction circuit is characterized in that, said RC filter circuit comprises RC filter and correcting circuit, and said RC filter comprises first resistance and the variable capacitance of serial connection, and said first resistance connects supply voltage, said variable capacitance ground connection; Said correcting circuit comprises comparator, controller and generating circuit from reference voltage; The input that of said comparator is used to obtain charging voltage is connected between first resistance and the variable capacitance, and another input that is used to obtain contrast potential is connected the output of generating circuit from reference voltage; The output that said comparator is used for the output voltage comparative result is connected with the input of controller, and the output that said controller is used to export regulating command connects said variable capacitance.
2. RC filter correction circuit as claimed in claim 1 is characterized in that said generating circuit from reference voltage is a resistor voltage divider circuit.
3. RC filter correction circuit as claimed in claim 2 is characterized in that said resistor voltage divider circuit comprises the resistance of two series connection, and an input of comparator is connected between two resistance; One termination power voltage of said resistor voltage divider circuit, other end ground connection.
4. RC filter correction circuit as claimed in claim 3 is characterized in that, the resistance of the resistance of said two series connection equates.
5. RC filter correction circuit as claimed in claim 1 is characterized in that said comparator is connected the said input between the variable capacitance and first resistance, between this input and comparator, also is serially connected with a low pass filter.
6. RC filter correction circuit as claimed in claim 1 is characterized in that said variable capacitance is a switched capacitor array.
7. like each described RC filter correction circuit of claim 1 to 6, it is characterized in that said RC filter comprises that also being located at being used between the variable capacitance and first resistance controls first switch that variable capacitance charges.
8. like each described RC filter correction circuit of claim 1 to 6, it is characterized in that said correcting circuit comprises that also be used to parallelly connected with variable capacitance control the second switch of variable capacitance discharge.
9. RC filter correction circuit as claimed in claim 7 is characterized in that, said correcting circuit comprises that also be used to parallelly connected with variable capacitance control the second switch of variable capacitance discharge.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120571778XU CN202455320U (en) | 2011-12-31 | 2011-12-31 | RC (resistor-capacitor) filter correction circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120571778XU CN202455320U (en) | 2011-12-31 | 2011-12-31 | RC (resistor-capacitor) filter correction circuit |
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| Publication Number | Publication Date |
|---|---|
| CN202455320U true CN202455320U (en) | 2012-09-26 |
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| CN201120571778XU Expired - Lifetime CN202455320U (en) | 2011-12-31 | 2011-12-31 | RC (resistor-capacitor) filter correction circuit |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102916679A (en) * | 2012-10-19 | 2013-02-06 | 钜泉光电科技(上海)股份有限公司 | Circuit for supplying precise low-frequency clock signal, and control method for circuit |
| CN103259532A (en) * | 2013-06-04 | 2013-08-21 | 中科院微电子研究所昆山分所 | Resistor-capacitor filter calibrating circuit |
| WO2014131305A1 (en) * | 2013-02-26 | 2014-09-04 | 中兴通讯股份有限公司 | Apparatus and system for correcting capacitor on chip |
| CN105807832A (en) * | 2014-12-30 | 2016-07-27 | 中国科学院深圳先进技术研究院 | Standard voltage stabilizing circuit |
| CN109302182A (en) * | 2018-08-27 | 2019-02-01 | 上海华虹集成电路有限责任公司 | A kind of RC time constant correcting circuit and method using time-to-digit converter (TDC) |
-
2011
- 2011-12-31 CN CN201120571778XU patent/CN202455320U/en not_active Expired - Lifetime
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102916679A (en) * | 2012-10-19 | 2013-02-06 | 钜泉光电科技(上海)股份有限公司 | Circuit for supplying precise low-frequency clock signal, and control method for circuit |
| WO2014131305A1 (en) * | 2013-02-26 | 2014-09-04 | 中兴通讯股份有限公司 | Apparatus and system for correcting capacitor on chip |
| CN103259532A (en) * | 2013-06-04 | 2013-08-21 | 中科院微电子研究所昆山分所 | Resistor-capacitor filter calibrating circuit |
| CN105807832A (en) * | 2014-12-30 | 2016-07-27 | 中国科学院深圳先进技术研究院 | Standard voltage stabilizing circuit |
| CN105807832B (en) * | 2014-12-30 | 2017-08-11 | 中国科学院深圳先进技术研究院 | Reference voltage-stabilizing circuit |
| CN109302182A (en) * | 2018-08-27 | 2019-02-01 | 上海华虹集成电路有限责任公司 | A kind of RC time constant correcting circuit and method using time-to-digit converter (TDC) |
| CN109302182B (en) * | 2018-08-27 | 2022-07-22 | 上海华虹集成电路有限责任公司 | RC time constant correction circuit and method adopting time-to-digital converter (TDC) |
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| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term |
Granted publication date: 20120926 |
|
| CX01 | Expiry of patent term |