CN110224675A - RC oscillating circuit - Google Patents
RC oscillating circuit Download PDFInfo
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- CN110224675A CN110224675A CN201910388930.1A CN201910388930A CN110224675A CN 110224675 A CN110224675 A CN 110224675A CN 201910388930 A CN201910388930 A CN 201910388930A CN 110224675 A CN110224675 A CN 110224675A
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- 230000010355 oscillation Effects 0.000 description 9
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- 238000007599 discharging Methods 0.000 description 5
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- 239000002184 metal Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
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- VOYADQIFGGIKAT-UHFFFAOYSA-N 1,3-dibutyl-4-hydroxy-2,6-dioxopyrimidine-5-carboximidamide Chemical compound CCCCn1c(O)c(C(N)=N)c(=O)n(CCCC)c1=O VOYADQIFGGIKAT-UHFFFAOYSA-N 0.000 description 1
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
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- 238000007493 shaping process Methods 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/20—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising resistance and either capacitance or inductance, e.g. phase-shift oscillator
Abstract
A kind of RC oscillating circuit, it include: offset generating circuit, including the first variable resistance, second resistance, the first end of second resistance is grounded, second end is connected to the second end of the first variable resistance, first variable resistance first end is connected to supply voltage, and the first end of the first variable resistance is as high voltage reference voltage output end, and the first variable resistance second end is as low pressure reference voltage output terminal；Capacitor charge and discharge circuit, including charge and discharge capacitance, charge and discharge capacitance first end ground connection, second end pass through switch respectively and are connected to charging current source and discharge current source；Comparator circuit generates control signal, including first comparator, the second comparator and Logic control module according to the output signal of first comparator and the second comparator to control the periodic charge and discharge of capacitor charge and discharge circuit.The Adjustment precision of above-mentioned RC oscillating circuit is higher and low in energy consumption.
Description
Technical field
The present invention relates to electronic technology field more particularly to a kind of RC oscillating circuits.
Background technique
Oscillator is the important component of many electronic systems.It generates from the clock of microprocessor into cellular phone
Carrier wave synthesis, oscillator are ubiquitous.Moreover, in different applications, it is required that structure and performance parameters difference it is very big.Vibration
It swings device and is generally divided into RC oscillator, LC oscillator, quartz oscillator etc..RC oscillating circuit is using a kind of most common vibration
Device circuit is swung, structure is simple, cost is relatively low, power consumption is also smaller.But it is affected by operating voltage and temperature change, work
Skill correlation is poor, and precision is also poor.
Traditional RC oscillation electric appliance can be able to satisfy one of high-precision or low-power consumption both performances, reach high
When precision, the electric current of consumption can be much larger or when this realizes low-power consumption work, and precision is inadequate.
According to capacitor charge and discharge formula, IT=CU, wherein I is electric current, and T is cycle of oscillation, and C is capacitance, and U is
Voltage.Traditional RC oscillation oscillator can calibrate electric current I, adjust the big of operating current I by multiple unitary current parallel connections
It is small.But to realize high precision, such as 2/10000ths precision, need 5000 unitary current parallel connections, each unit electricity
Stream is 2/10000ths of total current.It is 100nA when choosing glucose current equation, the maximum current of calibration can reach 5000 × 100nA
=0.5mA cannot achieve low-power consumption, and the matching precision of electric current is poor, equally can not achieve high-precision.If only to capacitor C
It is calibrated, the size of charge and discharge capacitance, such as 2/10000ths precision is adjusted by multiple specific capacitance parallel connections, needs 5000
A specific capacitance is in parallel.Assuming that the area of specific capacitance is 4 μm 4 μm, the maximum capacitor area of calibration is 50004 μm of 4 μ
M=8000 μm2, very big chip area can be occupied, seriously promotes cost, and the metal connecting line parasitic capacitance of bulky capacitor is also suitable
Greatly, in some instances it may even be possible to be greater than unit capacitance values, can not realize the high-precision of frequency calibration.
Therefore, how to realize that the oscillating circuit of high-precision and low-power consumption is current urgent problem to be solved.
Summary of the invention
The technical problem to be solved by the present invention is to improve the Adjustment precision of oscillating circuit, reduce power consumption.
To solve the above-mentioned problems, the present invention provides a kind of RC oscillating circuits, comprising: offset generating circuit, for producing
Raw low pressure reference voltage and high voltage reference voltage, including the first variable resistance, second resistance, the first termination of the second resistance
Ground, second end are connected to the second end of first variable resistance, and the first variable resistance first end is connected to supply voltage,
The first end of first variable resistance is as high voltage reference voltage output end, and the first variable resistance second end is as low pressure
Reference voltage output terminal；Capacitor charge and discharge circuit, including charge and discharge capacitance, the charge and discharge capacitance first end ground connection, second end
Charging current source and discharge current source are connected to by switch respectively；Comparator circuit, including first comparator, the second comparator
And Logic control module, the positive input terminal of the first comparator are connected to the positive reference voltage output terminal, described the
The negative input end of two comparators is connected to the low pressure reference voltage output terminal, the negative input end of the first comparator and described
The positive input terminal of second comparator is connected to the second end of the capacitor, the output end of the first comparator and the second comparator
It is respectively connected to the Logic control module, the Logic control module is used for according to the first comparator and the second comparator
Output signal, generate control signal, to control the periodic charge and discharge of the capacitor charge and discharge circuit.
Optionally, the supply voltage is provided by low pressure difference linear voltage regulator.
Optionally, the charging current source and discharge current source are provided by the low pressure difference linear voltage regulator.
Optionally, first variable resistance includes: the roughly adjusted rheostat array and accurate adjustment electric resistance array of series connection.
Optionally, the roughly adjusted rheostat array includes the resistance string that multiple resistance are in turn connected into, and described first can power transformation
The first end and/or second end of resistance are connect by switch selection circuit with the resistance string, select electricity by controlling the switch
The switch state respectively switched in road adjusts the resistance value of the roughly adjusted rheostat array.
Optionally, the accurate adjustment electric resistance array includes the fixed resistance branch being connected in parallel, secondary accurate adjustment resistance branch and essence
Resistance branch is adjusted, the resistance that the resistance Adjustment precision of the accurate adjustment resistance branch is greater than the secondary accurate adjustment resistance branch adjusts essence
Degree.
Optionally, the secondary accurate adjustment resistance branch and accurate adjustment resistance branch respectively include the electricity that multiple resistance are in turn connected into
Resistance string, is respectively connected to switch selection circuit, adjusts institute by controlling the switch state respectively switched in the switch selection circuit
State the resistance value of time accurate adjustment resistance branch and accurate adjustment resistance branch.
Optionally, the charge and discharge capacitance unit calibration section within -3%~3%, piece calibration section -
Within 50%~50%.
Optionally, the first end of first variable resistance is connected to supply voltage by a switch.
Optionally, the Logic control module includes rest-set flip-flop, the output of the first comparator and the second comparator
End is respectively connected to the end R and the end S of the rest-set flip-flop, controls the capacitor by the control signal that the rest-set flip-flop exports
The periodic charge and discharge of charge-discharge circuit.
Optionally, the Logic control module further includes the first reverse phase of the output end based on the rest-set flip-flop time connection
Device and the second phase inverter.
RC oscillating circuit of the invention includes the first variable resistance in offset generating circuit, first variable resistance
Resistance value is able to carry out high-precision adjustment, so that high-precision adjustment is carried out to high voltage reference voltage, to realize to frequency of oscillation
High-precision adjustment.
Detailed description of the invention
Fig. 1 is the electrical block diagram of the RC oscillating circuit of the embodiment of the invention；
Fig. 2 is the triangular waveform schematic diagram of the embodiment of the invention；
Fig. 3 is the triangular waveform schematic diagram of the embodiment of the invention；
Fig. 4 is the structural schematic diagram of the first variable resistance of the embodiment of the invention；
Fig. 5 is the structural schematic diagram of the roughly adjusted rheostat array of the embodiment of the invention；
Fig. 6 is the structural schematic diagram of the accurate adjustment electric resistance array of the embodiment of the invention.
Specific embodiment
It elaborates with reference to the accompanying drawing to the specific embodiment of RC oscillating circuit provided by the invention.
Referring to FIG. 1, the structural schematic diagram of the RC oscillating circuit for the embodiment of the invention.
The RC oscillating circuit includes offset generating circuit 101, capacitor charge and discharge circuit 102 and comparator circuit 103.
The offset generating circuit 101 is for generating low pressure reference voltage VL and high voltage reference voltage VH.
In the specific embodiment, the offset generating circuit 101 includes the first variable resistance R1 and second resistance R2, institute
The first end ground connection GND of second resistance R2 is stated, second end is connected to the second end of the first variable resistance R1, and described first can
Power transformation resistance R1 first end is connected to supply voltage, and the first end of the first variable resistance R1 is as high voltage reference voltage output
End, for exporting low pressure reference voltage VH, the first variable resistance R1 second end is connected to low pressure reference voltage output terminal, uses
In output low pressure reference voltage VL.Can be adjusted by adjusting the resistance value of the first resistor R1 and second resistance R2 the VH and
The value of VL.
In the specific embodiment, the supply voltage is provided by low pressure difference linear voltage regulator LP_LDO, and described first can
Power transformation resistance R1 first end is connected to the supply voltage output end of the low pressure difference linear voltage regulator, the low pressure difference linear voltage regulator
Burning voltage is exported, can reduce influence of the variation to output frequency of supply voltage.The low pressure difference linear voltage regulator LP_LD
Switching device M1 is connected between the first resistor R1 first end, the switching device M1 has enable end, by enabled
Signal EN can control the turn-on and turn-off of the switching device M1, switching device M1 the opening as entire RC oscillating circuit
It closes.When the switching device M1 be connected, due to the switching device M1 conducting electric current stablize, the low pressure reference voltage VL and
The size of high voltage reference voltage VH can be adjusted by the resistance value of the first variable resistance R1 and second resistance R2.The specific implementation
In mode, the resistance value of the second resistance R2 is fixed, and the low pressure reference voltage VL is fixed；The first variable resistance R1's
Resistance value is adjustable, and the high voltage reference voltage VH can be changed by the first variable resistance R1, and described first is variable
The Adjustment precision of resistance R1 determines the Adjustment precision of the high voltage reference voltage VH.
The capacitor charge and discharge circuit 102 includes charge and discharge capacitance C, the charge and discharge capacitance C first end ground connection, second end
Q1 passes through switch respectively and is connected to charging current source I_charge and discharge current source I_discharge.The charge and discharge capacitance C
It is connected to charging current source I_charge by first switch K1, charging current source I_ is connected to by second switch K2
Discharge can control the charge and discharge by controlling the conducting and off-state of the first switch K1 and second switch K2
The charging and discharging state of capacitor C.The charging current source I_charge and discharge current source I_discharge can pass through institute
Low pressure difference linear voltage regulator LP_LDO offer is stated, charge and discharge capacitance second end Q1 passes through switch respectively and is connected to the low voltage difference line
The charging current source output terminal and discharge current source output terminal that property voltage-stablizer LP_LDO is mentioned, to provide stable charging and discharging currents,
Reduce influence of the variation of charging and discharging currents to output frequency.
When the first switch K1 is connected, second switch K2 is disconnected, and the charge and discharge capacitance C is connected to charging current source I_
Charge charges to the charging and discharging currents C；When the first switch K1 is disconnected, second switch K2 is connected, the charge and discharge
Capacitor C is connected to discharge current source I_discharge, and the charging and discharging currents C discharges.Periodically switch described
The on state of one switch K1 and second switch K2 can carry out periodic charge and discharge to the capacitor C, to export the period
The oscillator signal of property.The first switch K1 and second switch K2 is circuit or device with switching characteristic, is not limited herein
It is fixed.
The comparator circuit 103 includes first comparator COMP1 and the second comparator COMP2 and logic control mould
Block.The low pressure reference voltage VL and high voltage reference voltage VH is respectively as first comparator COMP1 and the second comparator COMP2
Reference voltage, the high voltage reference voltage VH is input to the positive input terminal of the first comparator COMP1, the low pressure reference
Voltage VL is input to the negative input end of the second comparator COMP2.The negative input end and second of the first comparator COMP1
The positive input terminal of comparator COMP2 is connected to the second end Q1 of the charging capacitor C, by the voltage of the charging capacitor C and institute
It states low pressure reference voltage VL and high voltage reference voltage VH is compared, and export comparison signal respectively to the logic control mould
Block exports the control signal control capacitor charge and discharge circuit 102 by the Logic control module and carries out periodic charge and discharge,
Specifically, the switch state of the first switch K1 and second switch K2 are controlled by the control signal, thus output amplitude
Oscillator signal between VL~VH.
The Logic control module includes rest-set flip-flop TRI, and the output signal of the first comparator COMP1 is exported to institute
The R input of rest-set flip-flop TRI is stated, the output signal of the second comparator COMP2 is exported to the S of the rest-set flip-flop TRI
Input terminal, the Q output of the rest-set flip-flop TRI is as control signal output, can also be in other specific embodiments
Using the non-end Q as control signal output.In the specific embodiment, the rest-set flip-flop TRI is using two NAND gates
The structure of input and output interconnection, R input 0, Q and export 1, S, 0, Q of input output 0.It, can also in other specific embodiments
With using other circuit structures trigger or other can be realized the circuit devcie of above-mentioned Trigger Function.
In the specific embodiment, the Logic control module further includes be in turn connected to the rest-set flip-flop TRI
One phase inverter Invr1 and the second phase inverter Invr2 passes through the reverse phase twice of the control signal exported to the rest-set flip-flop TRI
Operation carries out shaping to the control signal, improves the validity of the control signal.In other specific embodiments,
Can only have the phase inverter of a phase inverter or three or more, and the fewer phase inverter the better.
Referring to FIG. 2, exporting the waveform diagram of triangular wave for the charge and discharge capacitance C.
When K1 is opened, charge and discharge capacitance C is electrically charged, when the voltage of capacitor C reaches VH, first comparator COMP1 output
The input end 0, Q R of 0, the second comparator COMP2 output 1, the end the Q output 1 of rest-set flip-flop TRI, i.e. rest-set flip-flop is anti-by two-stage
1 is exported after phase device Invr1 and Invr2, is opened to control the first switch K1, second switch K2 closure, charge and discharge capacitance C
It discharges；When charge and discharge capacitance discharges, when voltage drops to VL, first comparator COMP1 output 1, the second comparator COMP2
Two-stage phase inverter Invr1 and Invr2 is passed through at the S input end 0, Q of output 0, the end the Q output 0 of rest-set flip-flop TRI, i.e. rest-set flip-flop
After export 0, to control first switch K1 closure, second switch K2 is opened, is charged to charge and discharge capacitance C.So
Charge and discharge periodically are carried out to charge and discharge capacitance C, export periodic triangle waveform, frequency of oscillation f0=1/T.
In another specific embodiment, only level-one reverse phase only can be connected by the output end with the rest-set flip-flop TRI
Device Invr1 or Invr2, when the voltage of capacitor C reaches VH, first comparator COMP1 output 0, the second comparator COMP2 output
The R input end 0, Q of the end the Q output 1 of 1, rest-set flip-flop TRI, i.e. rest-set flip-flop exports 0 after level-one phase inverter, described in control
First switch K1 is opened, and second switch K2 closure, charge and discharge capacitance C discharges；When voltage drops to VL, first comparator
The end the Q output 0 of COMP1 output 1, the second comparator COMP2 output 0, rest-set flip-flop TRI exports 1 after level-one phase inverter, control
The first switch K1 closure, second switch K2 are opened, are charged to charge and discharge capacitance C.
The triangular waveform can be calibrated by adjusting the value of the high voltage reference voltage VH.
Referring to FIG. 3, when VH variation precision is 0.02%, when the rising waveform of triangular waveform is to VH (1+0.02%),
Start to discharge.If beginning cycle of oscillation is T, corresponding frequency is f0=1/T；Period after calibration is T (1+0.02%), right
The frequency answered is approximately f0 (1-0.02%), to realize high-precision calibration.
The value of the high voltage reference voltage VH can be adjusted by the first variable resistance R1, therefore, described
The Adjustment precision of one variable resistance R1 determines the Adjustment precision of the high voltage reference voltage VH, and then determines entire oscillation electricity
The Adjustment precision of the frequency of oscillation on road.
Referring to FIG. 4, the first variable resistance R1 includes the roughly adjusted rheostat battle array being connected in series in the specific embodiment
Arrange R11 and accurate adjustment electric resistance array R12.
The roughly adjusted rheostat array R11 can carry out the biggish coarse adjustment of amplitude to the resistance value of R1, when needing significantly to adjust
When VH value, regulated efficiency can be improved.The accurate adjustment electric resistance array R12 is used to carry out accurate adjustment to the resistance value of R1, carries out to R1 micro-
It adjusts, the Adjustment precision of the accurate adjustment electric resistance array R12 determines the Adjustment precision of R1 and the variation precision of VH.
The roughly adjusted rheostat array R11 and accurate adjustment electric resistance array R12 may each comprise multiple resistance, can be respectively by opening
Powered-down road selects the resistance of access, so as to adjust the resistance value of electric resistance array R11 and accurate adjustment electric resistance array R12.It is specific real at one
It applies in mode, the electric resistance array R11 and accurate adjustment electric resistance array R12 include that the cell resistance of unit length-width ratio size forms
Array can be required according to Adjustment precision, the resistance value of selecting unit resistance.Since the length-width ratio of cell resistance is consistent, matching
It can accomplish very accurately, and the metal connecting line resistance between unit resistance is fairly small, can ignore for entire resistance value.
The opening and closing shape respectively switched in the first variable resistance R1 can be controlled by resistance adjustment signal RTRIM
State adjusts the resistance of the first variable resistance R1 to realize.
Referring to FIG. 5, the structural schematic diagram of the roughly adjusted rheostat array R11 for the embodiment of the invention.
The roughly adjusted rheostat array R11 includes the resistance string that multiple resistance are in turn connected into, and the resistance value of each resistance can be with
It is identical or different.Each resistance can may be multiple sub- resistance compositions for single resistance.It is described in the specific embodiment
Roughly adjusted rheostat array R11 includes the resistance string that the identical resistance of several resistance values is sequentially connected with composition.Fig. 5 is not only as an example,
Represent actual resistance quantity in the roughly adjusted rheostat array R11.The roughly adjusted rheostat array R11 further includes first switch selection
Circuit K11, including several switches, are connected to the resistance string, are specifically connected on the connecting line between each resistance.Pass through
The switch state of each switch is controlled, concatenated resistance between the end top and the end bot of roughly adjusted rheostat array R11 is selected.In Fig. 5
First switch selection circuit K11 only as an example, in other specific embodiments, can also use other circuit forms,
As long as the resistance value of the roughly adjusted rheostat array R11 can be adjusted with certain precision.
In the specific embodiment, the roughly adjusted rheostat array R11 includes the resistance R111 of multiple similar resistances, described thick
The resistance value that the Adjustment precision of electric resistance array R11 is single resistance R111 is adjusted, convenient for the tune of the roughly adjusted rheostat array R11 resistance value
It is whole.In a specific embodiment, the resistance value of single resistance R111 is equal to 2r, is connected in series by two unit resistances.According to
It is secondary to be switched on and off different switches, the available different resistance value between the end top and the end bot, such as 0,2r, 4r, 6r.
The switch state of each switch can be controlled respectively by controlling signal, to obtain different R11 resistance values.
In the specific embodiment, the switch selection circuit K11 connection end top of the roughly adjusted rheostat array R11 with
Resistance string；In other specific embodiments, the switch selection circuit K11 can also connect the end bot and resistance string, or
Person part connects the end top and resistance string, partially connects the end bot and resistance string.
Referring to FIG. 6, the structural schematic diagram of the accurate adjustment electric resistance array R12 for the embodiment of the invention.
The accurate adjustment electric resistance array includes the fixed resistance branch being connected in parallel, secondary accurate adjustment resistance branch and accurate adjustment resistance branch
Road, the resistance Adjustment precision of the accurate adjustment resistance branch are greater than the resistance Adjustment precision of the secondary accurate adjustment resistance branch.
In the specific embodiment, the resistance value of the fixed resistance branch is fixed, including a resistance R121.
The secondary accurate adjustment resistance branch includes the resistance string of multiple sequentially connected resistance compositions, including multiple resistance values are identical
Resistance R122 also may include the different resistance of multiple resistance values in other specific embodiments.The secondary accurate adjustment resistance branch
Road further includes second switch selection circuit K122, including several switches, is connected to the resistance string of the secondary accurate adjustment resistance branch, tool
On the connecting line of body being connected between each resistance.By controlling the switch state of each switch, time accurate adjustment resistance branch is selected
The end top and the end bot between concatenated resistance value.Second switch selection circuit K122 in Fig. 6 is only as an example, in other tools
It, can also be using other circuit forms, as long as the secondary accurate adjustment resistance branch can be adjusted with certain precision in body embodiment
The resistance value on road.In the specific embodiment, the second switch selection resistance K122 tool is respectively connected to there are three switch
Between two connecting pins and one of resistance and the end top between three resistance.
The accurate adjustment resistance branch includes the resistance string of multiple sequentially connected resistance compositions, including multiple resistance values are identical
Resistance R123 also may include the different resistance of multiple resistance values in other specific embodiments.The accurate adjustment resistance branch
Resistance quantity is more than time resistance quantity of accurate adjustment resistance branch.The accurate adjustment resistance branch further includes third switch selection circuit
K123, including several switches are connected to the resistance string of the accurate adjustment resistance branch, the company being specifically connected between each resistance
In wiring.By controlling the switch state of each switch, concatenated resistance between the end top and the end bot of accurate adjustment resistance branch is selected
Value.Third switch selection circuit K123 in Fig. 6 only as an example, in other specific embodiments, can also use other
Circuit form, as long as the resistance value of the secondary accurate adjustment resistance branch can be adjusted with certain precision.The specific embodiment
In, the accurate adjustment resistance branch includes three sub- resistance strings, is respectively connected to three sub- switching circuits, passes through sub switch circuit point
The resistance value of each sub- resistance string is not adjusted, then the resistance value of entire accurate adjustment resistance branch is adjusted by the selection of another sub switch circuit.
Since the fixed resistance branch, secondary accurate adjustment resistance branch and accurate adjustment resistance branch are connected in parallel, total resistance value can be small
In the resistance value of any branch.
In a specific embodiment, the resistance value for adjusting the fixed resistance branch is 3r, the secondary accurate adjustment resistance branch
The resistance value on road is 3r, and the resistance value of accurate adjustment resistance branch is 4.5r, and the parallel resistance value of three branches is 1.125r；Work as fixed resistance
The resistance value of branch is 3r, and the resistance value of secondary accurate adjustment resistance branch is 3r, when the resistance value of accurate adjustment resistance branch is adjusted to 7.5r, at this time simultaneously
Connection resistance value is 1.25r, has only changed Δ=0.125r than a upper resistance value.By selecting suitable resistance coefficient and opening
Suitable to switch to guarantee in calibration, the adjacent increased resistance value Δ that obtains keeps stablizing.Above-mentioned accurate adjustment electric resistance array R12 is adjusted
Resistance value can connect resistance value after being added equally with resistance value Δ with the roughly adjusted rheostat array in this way from r even variation to 3r
Dull accurate variation.
High calibration accuracy, the biased electrical in biasing circuit are obtained by way of electric resistance partial pressure and resistor coupled in parallel
Stream is smaller, and power consumption is lower.And, it is only necessary to small number of resistance, it will be able to realize the high-precision of resistance value adjustment.
In a specific embodiment, the value of resistance adjustment signal RTRIM can change to 11 from 00,0000,0000,
1111,1111,10 resistance calibration positions altogether.When RTRIM value is 10,0000,0000, it is corresponding at this time be first can power transformation
The resistance value for hindering R1 is benchmark resistance value；When RTRIM value is 00,0000,0000, the resistance of corresponding first variable resistance R1
Value is minimum value；When rtrim value is 11,1111,1111, the resistance value of corresponding first variable resistance R1 is adjustable resistance
Maximum value.
In a specific embodiment, the reference resistance is exactly the resistance value that resistance calibration position is median, and such as ten
Position calibration bits 10,0000,0000；RTRIM changes one, such as changes to 10,0000,0001 from 10,0000,0000, resistance value
Change 0.125r；When the Adjustment precision that realize 2/10000ths, it is only necessary to set the reference resistance of the first variable resistance R1
For 0.125r/0.0002=625r, i.e., when RTRIM value is 1000000000, the resistance value of corresponding first variable resistance R1 is
625r.Here the every variation one of calibration bits, resistance change amount Δ=0.125r can be according to selection first variable resistance
The parallel value of R1 different branches obtains, and without limitation.In other specific embodiments, RTRIM value changes one, electricity
The variable quantity of resistance value may be set to be other values.
The digit of the resistance calibration position of the RTRIM is selected according to the deviation of charge and discharge capacitance C, can with described first
It is not related that power transformation hinders R1.For example, can use 9 RTRIM values when 2/10000ths Adjustment precision requires, ± 3% can be covered
The process deviation of capacitor, i.e. 0.0002 × 256=5.12% > 3%, (herein 256 be 2 systems 1,0000,0000 to 1,1111,
Difference between 1111 or 1, the difference between 0000,0000 to 0,0000,0000)；Select 10 rtrim values, 0.0002
× 512=10.24% can much cover be more than ± 3% capacitor process deviation.
The capacitor charge and discharge circuit consumption electric current of the pierce circuit is only 0.35 μ A, can satisfy the requirement of low-power consumption.
In other specific embodiments, the resistance coefficient of each resistance according to the demand of Adjustment precision, can be set and opened
The control mode of pass.The resistance coefficient is the ratio between a resistance actual resistance and unitary resistance value.
It, can also be first by before being adjusted to the first variable resistance R1 in other specific embodiments
The charge and discharge capacitance C is calibrated, the unit calibration section of the charge and discharge capacitance is within -3%~3%, whole school
Quasi- section is within -50%~50%, to cover all process corner variations.Here, unit of capacity calibration section refers to that calibration bits are every
Variation one, such as five calibration bits from 10000 change to 10001 perhaps 01111 when capacitor value variation -3% or 3%；It is whole
The quasi- section of sports school refer to when five calibration bits from 10000 change to 11111 perhaps 00000 when in total variation -50% or
50%.Here process corner refers to the deviation of the processing line parameter of production chip, such as the target value of capacitor is 1pF, but in fact
That produce may be 0.9pF or 1.1pF, by select suitable calibration value available it is desirable that 1pF capacitor
Value.
It can be calibrated by capacitance of the capacitor adjustment signal CRTIM to capacitor C.
Above-mentioned RC oscillating circuit includes the first variable resistance, the resistance value of first variable resistance in offset generating circuit
It is able to carry out high-precision adjustment, so that high-precision adjustment is carried out to high voltage reference voltage, to realize the height to frequency of oscillation
Precision adjustment.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
Member, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications also should be regarded as
Protection scope of the present invention.
Claims (11)
1. a kind of RC oscillating circuit characterized by comprising
Offset generating circuit, for generating low pressure reference voltage and high voltage reference voltage, including the first variable resistance, the second electricity
Resistance, the first end ground connection of the second resistance, second end are connected to the second end of first variable resistance, and described first is variable
Resistance first end is connected to supply voltage, and the first end of first variable resistance is described as high voltage reference voltage output end
First variable resistance second end is as low pressure reference voltage output terminal；
Capacitor charge and discharge circuit, including charge and discharge capacitance, the charge and discharge capacitance first end ground connection, second end pass through switch respectively
It is connected to charging current source and discharge current source；
Comparator circuit, including first comparator, the second comparator and Logic control module, the first comparator it is just defeated
Enter end and be connected to the positive reference voltage output terminal, the negative input end of second comparator is connected to the low pressure with reference to electricity
Press output end, the positive input terminal of the negative input end of the first comparator and second comparator is connected to the of the capacitor
The output end of two ends, the first comparator and the second comparator is respectively connected to the Logic control module, the logic control
Molding block is used for the output signal according to the first comparator and the second comparator, control signal is generated, to control the electricity
Hold the periodic charge and discharge of charge-discharge circuit.
2. RC oscillating circuit according to claim 1, which is characterized in that the supply voltage is by low pressure difference linear voltage regulator
It provides.
3. RC oscillating circuit according to claim 1, which is characterized in that the charging current source and discharge current source are by institute
Low pressure difference linear voltage regulator offer is provided.
4. RC oscillating circuit according to claim 1, which is characterized in that first variable resistance includes: to be connected in series
Roughly adjusted rheostat array and accurate adjustment electric resistance array.
5. RC oscillating circuit according to claim 4, which is characterized in that the roughly adjusted rheostat array include multiple resistance according to
The secondary resistance string connected into, the first end and/or second end of first variable resistance pass through switch selection circuit and the electricity
Resistance series winding connects, and by controlling the switch state respectively switched in the switch selection circuit, adjusts the electricity of the roughly adjusted rheostat array
Resistance value.
6. RC oscillating circuit according to claim 4, which is characterized in that the accurate adjustment electric resistance array includes being connected in parallel
Fixed resistance branch, secondary accurate adjustment resistance branch and accurate adjustment resistance branch, the resistance Adjustment precision of the accurate adjustment resistance branch are greater than
The resistance Adjustment precision of the secondary accurate adjustment resistance branch.
7. RC oscillating circuit according to claim 6, which is characterized in that the secondary accurate adjustment resistance branch and accurate adjustment resistance branch
Road respectively includes the resistance string that multiple resistance are in turn connected into, and is respectively connected to switch selection circuit, by controlling the switch
The switch state respectively switched in selection circuit adjusts the resistance value of secondary the accurate adjustment resistance branch and accurate adjustment resistance branch.
8. RC oscillating circuit according to claim 1, which is characterized in that the unit of the charge and discharge capacitance calibrates section
Within -3%~3%, piece calibration section is within -50%~50%.
9. RC oscillating circuit according to claim 1, which is characterized in that the first end of first variable resistance passes through one
Switch is connected to supply voltage.
10. RC oscillating circuit according to claim 1, which is characterized in that the Logic control module includes rest-set flip-flop,
The output end of the first comparator and the second comparator is respectively connected to the end R and the end S of the rest-set flip-flop, passes through the RS
The control signal of trigger output controls the periodic charge and discharge of capacitor charge and discharge circuit.
11. RC oscillating circuit according to claim 10, which is characterized in that the Logic control module further includes based on institute
State the first phase inverter and the second phase inverter of the output end time connection of rest-set flip-flop.
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| CN201910388930.1A CN110224675A (en) | 2019-05-10 | 2019-05-10 | RC oscillating circuit |
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| CN201910388930.1A CN110224675A (en) | 2019-05-10 | 2019-05-10 | RC oscillating circuit |
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ID=67820882
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| CN111181491A (en) * | 2019-12-31 | 2020-05-19 | 成都锐成芯微科技股份有限公司 | Clock generating circuit |
| CN111969980A (en) * | 2020-10-26 | 2020-11-20 | 上海芯龙半导体技术股份有限公司南京分公司 | Oscillator circuit and power supply chip |
| CN112491397A (en) * | 2020-12-07 | 2021-03-12 | 成都锐成芯微科技股份有限公司 | Multi-frequency-point RC oscillator |
| CN112650092A (en) * | 2020-09-25 | 2021-04-13 | 合肥恒烁半导体有限公司 | Comparator, RC oscillator circuit and MCU chip |
| WO2022155888A1 (en) * | 2021-01-22 | 2022-07-28 | 深圳市汇顶科技股份有限公司 | Rc relaxation oscillator |
| WO2023016080A1 (en) * | 2021-08-11 | 2023-02-16 | 华润微集成电路(无锡)有限公司 | High-precision clock circuit structure |
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