CN104836577B - A kind of high precision oscillator structure suitable for MEMS applications - Google Patents
A kind of high precision oscillator structure suitable for MEMS applications Download PDFInfo
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- CN104836577B CN104836577B CN201410047674.7A CN201410047674A CN104836577B CN 104836577 B CN104836577 B CN 104836577B CN 201410047674 A CN201410047674 A CN 201410047674A CN 104836577 B CN104836577 B CN 104836577B
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Abstract
The present invention proposes a kind of high precision oscillator structure suitable for MEMS applications, according to the high precision oscillator structure that the present invention makes, designs oscillator using the structure of constant current charge and discharge, keeps it insensitive to mains voltage variations；For one constant current source of oscillator design, the electric current which generates is kept constant within the scope of certain temperature, and unrelated with supply voltage.
Description
Technical field
The present invention relates to technical field of integrated circuits more particularly to a kind of high precision oscillator knots suitable for MEMS applications
Structure circuit.
Background technology
Oscillator built in integrated circuit mostly uses simple line construction at present, is made with resistance capacitor charge and discharge time constant
For cycle of oscillation timing, since the resistance capacitance value of IC interior can all change with voltage, temperature, lead to oscillation frequency
Rate changes with supply voltage, environment temperature.Under normal circumstances, RC oscillators by the charge and discharge of resistance capacitance be delayed come
Frequency of oscillation is generated, generated frequency is easy to be influenced by supply voltage, temperature, in order to overcome supply voltage and temperature pair
The influence of RC oscillator output frequencies, numerous designs and invention propose high-precision RC oscillators.
In traditional application scenario, the occasion high to oscillator frequency required precision often uses crystal oscillator discrete outside piece
As clock source, and not only there are higher requirement in some application scenarios to the precision of clock, but also are not suitable for integrated external crystalline substance
It shakes, such as MEMS（Micro-Electro Mechanical system, microelectromechanical systems）Using etc., the present invention is directed to
The application and development is a can with the high precision oscillator of Embedded, and the precision and power consumption of the oscillator are moderate, Ke Yiying
For the relevant occasions of MEMS.
As shown in Figure 1, being traditional relaxation（relaxation）Oscillator structure 100, oscillator structure 100 is by power supply electricity
Press input terminal 101, clock signal generating module 102, current charging and discharging circuit 103.The clock signal generating module 102 includes
Bleeder circuit 104, comparator circuit 105, oscillating circuit 106 and d type flip flop circuit 107.Wherein, bleeder circuit 104 includes electricity
Resistance ladder 1041, switch 1042, switch 1043, oscillating circuit 106 include switch 1061, switch 1062 and capacitance 1063, d type flip flop
Circuit 107 includes d type flip flop 1071.
Under normal operation, the voltage that power voltage input terminal 101 provides obtains V by the partial pressure of resistor ladder 1041AAnd VBTwo
A voltage value, when the output of comparator circuit 105 is low level, switch 1042 and switch 1061 are connected, current charging and discharging
Circuit 103 starts to provide Iptat（Positive temperature coefficient correcting current）It charges to capacitance 1063, the voltage value on capacitance 1063
Reach VAWhen, the output of oscillating circuit 105 becomes high level；When the output of comparator circuit 105 is high level, switch
1042 disconnect with switch 1061, and switch 1043 and switch 1062 are connected, and current charging and discharging circuit 103 starts to provide Iptat（Positive temperature
Spend coefficient correction electric current）Capacitance 1063 discharges, when the voltage on capacitance 1063 drops to VBWhen, comparator circuit 105 is again
Secondary output low level, so as to complete a cycle of oscillation.Pass through 107 output signal of d type flip flop circuit, specifically, d type flip flop
Voltage waveform on 1071 pairs of capacitances 1063 carries out shaping and frequency dividing finally obtains a good square-wave signal conduct of empty accounting
The final output signal of oscillator exports high RST by the output end of d type flip flop circuit 107.The output frequency of oscillator structure 100
Rate is f=1/T=Iptat/（2*C*（VA-VB））.
However, since the voltage value that supply voltage provides is variation, this voltage difference of VA-VB will be caused also with electricity
The variation for the voltage value that source voltage provides and change so that the output frequency of oscillator can also be provided with supply voltage
The variation of voltage value and change, affect the precision of oscillator output frequencies.For the electric current to capacitor charge and discharge in oscillator
Charge-discharge circuit is usually to be generated by a band-gap reference circuit, size and the temperature phase of the electric current of the current charging and discharging circuit
It closes, the electric current can also change when the temperature is changed, and when temperature is from when changing to 100 DEG C for -40 DEG C, the variation of the electric current can generally surpass
50% is crossed, the precision of oscillator output frequencies has been seriously affected.
Therefore, it is badly in need of a kind of high precision oscillator structure suitable for MEMS applications at present, to solve existing oscillator knot
The problem of structure.
Invention content
A series of concept of reduced forms is introduced in Summary, this will in the detailed description section into
One step is described in detail.The Summary of the present invention is not meant to attempt to limit technical solution claimed
Key feature and essential features do not mean that the protection domain for attempting to determine technical solution claimed more.
In order to solve the problems in the existing technology, the present invention propose it is a kind of suitable for MEMS application high-precision shake
Device structure is swung, including：Reference voltage generation module, reference current generation module and clock signal generating module；The benchmark electricity
Pressure generation module is connected with the clock signal generating module, to provide the reference voltage unrelated with supply voltage and temperature
VREF；The reference current generation module is connected with the clock signal generating module；To provide it is stable with supply voltage and
The unrelated reference current I of temperatureREF；The clock signal generating module includes bleeder circuit, comparator circuit, oscillating circuit and D
Flip-flop circuit；The input terminal of the bleeder circuit is connected with the reference voltage generation module, the output of the bleeder circuit
End is connected with the first input end of the comparator circuit；The output end of the comparator circuit and with the d type flip flop circuit
It is connected；The input terminal of the oscillating circuit is connected with the reference current generation module, the output end of the oscillating circuit and institute
The second input terminal for stating comparator circuit is connected.
Preferably, the reference voltage generation module includes band-gap reference circuit circuit, the first operational amplifier, the second fortune
Calculate amplifier, third operational amplifier, first resistor, second resistance, 3rd resistor, the 4th resistance, first voltage output end and
Second voltage output end.
Preferably, the band-gap reference circuit is connected with the first operational amplifier in-phase input end, the band gap base
Quasi- circuit is connected with the second operational amplifier in-phase input end.
Preferably, the output end of first operational amplifier is connected with the first voltage output end, first fortune
The output end for calculating amplifier is connected with the first end of the first resistor, the second end of the first resistor and the third operation
The in-phase input end of amplifier is connected, and the output end of the third operational amplifier is connected with the second voltage output end, institute
The second end for stating first resistor is connected with the first end of the second resistance, the second end ground connection of the second resistance.
Preferably, the output end of the second operational amplifier is connected with the first end of the 3rd resistor, the third
The second end of resistance is connected with the inverting input of the third operational amplifier, the second end of the 3rd resistor and described the
The first end of four resistance is connected, and the first end of the 4th resistance is connected with the inverting input of the third operational amplifier,
The second end of 4th resistance is connected with the output end of the third operational amplifier.
Preferably, the band-gap reference circuit generates the voltage V unrelated with supply voltage and temperatureREF1And it is electric with power supply
Press the specific voltage V of unrelated but negative temperature coefficientbe1, the first voltage output end exports unrelated with supply voltage and temperature
Reference voltage VREF, the adjustable voltage V of second voltage output end output temperature coefficientbe2。
Preferably, the ratio of the 3rd resistor and the 4th resistance is adjusted to change the voltage Vbe2Temperature system
Number and polarity, the ratio for adjusting the first resistor and the second resistance adjust the voltage Vbe2Central point voltage value
Preferably, the reference current generation module includes：First voltage input terminal, second voltage input terminal, the 5th electricity
Resistance, the output of the 6th resistance, the 7th resistance, four-operational amplifier, the 5th operational amplifier, metal-oxide-semiconductor, current mirroring circuit, electric current
End.
Preferably, the second voltage input terminal is connected with the in-phase input end of the four-operational amplifier, and described
One voltage input end is connected with the first end of the 5th resistance, and the of the second end of the 5th resistance and the 6th resistance
One end is connected, and the second end of the 5th resistance is connected with the inverting input of the four-operational amplifier, the 6th electricity
The first end of resistance is connected with the inverting input of the four-operational amplifier, the second end and the described 4th of the 6th resistance
The output end of operational amplifier is connected, the second end of the 6th resistance and the output end of the four-operational amplifier with it is described
The in-phase input end of 5th operational amplifier is connected.
Preferably, the first end of the 7th resistance is connected with the inverting input of the 5th operational amplifier, described
The first end of 7th resistance is connected with the source electrode of the metal-oxide-semiconductor, and the second end ground connection of the 7th resistance, the 5th operation is put
The output end of big device is connected with the grid of the metal-oxide-semiconductor, and the drain electrode of the metal-oxide-semiconductor is connected with the current mirroring circuit, the electricity
Current mirror circuit is connected with the current output terminal, and the current output terminal is for exporting the benchmark unrelated with supply voltage and temperature
Electric current IREF。
Preferably, the adjustable voltage V of first voltage input terminal input temp coefficientbe2, the second voltage input terminal
The input reference voltage V unrelated with supply voltage and temperatureREF。
Preferably, the voltage V of the temperature coefficient adjustable inputted by the first voltage input terminalbe2, it is described 5th electricity
Resistance, the 6th resistance, the four-operational amplifier generate arbitrary temp coefficient and polar voltage VC。
Preferably, by with the voltage VCThe 7th resistance of identical polar and temperature coefficient come obtain and power supply electricity
Pressure and the unrelated reference current I of temperatureREF。
Preferably, the expression formula of the signal frequency of the d type flip flop circuit output be f=【IREF/（2*C*（VA-VB））】*
0.5, wherein VAAnd VBFor VREFBranch pressure voltage, C is capacitance.
In conclusion manufacturing method according to the invention proposes a kind of high precision oscillator knot suitable for MEMS applications
Structure designs oscillator using the structure of constant current charge and discharge, keeps it insensitive to mains voltage variations；For oscillator design
One constant current source, the electric current which generates are kept constant within the scope of certain temperature, and with supply voltage without
It closes.
Description of the drawings
The following drawings of the present invention is used to understand the present invention in this as the part of the present invention.Shown in the drawings of this hair
Bright embodiment and its description, principle used to explain the present invention.In the accompanying drawings,
Fig. 1 is the structural schematic diagram of the oscillator structure made according to the prior art；
Fig. 2A is the structural schematic diagram of the oscillator structure made according to the present invention；
Fig. 2 B are the structural schematic diagram of reference voltage generation module in the oscillator structure made according to the present invention；
Fig. 2 C are the structural schematic diagram of reference current generation module in the oscillator structure made according to the present invention.
Specific implementation mode
In the following description, a large amount of concrete details are given in order to provide more thorough understanding of the invention.So
And it will be apparent to one skilled in the art that the present invention may not need one or more of these details and be able to
Implement.In other examples, in order to avoid with the present invention obscure, for some technical characteristics well known in the art not into
Row description.
In order to thoroughly understand the present invention, detailed step will be proposed in following description, so as to illustrate the present invention be as
What is using a kind of new using current mirroring circuit as the electrostatic discharge protection circuit of trigger circuit, to be effectively reduced capacitance resistance
Design area requirement.Obviously presently preferred embodiments of the present invention is detailed is described as follows, however removes outside these detailed descriptions, this hair
It is bright to have other embodiment.
The present invention proposes a kind of new using current mirroring circuit as the electrostatic discharge protection circuit of trigger circuit.Fig. 2A is root
According to the structural schematic diagram for the oscillator structure that the present invention makes.In order to more specifically describe the present invention, with reference to Fig. 2A and
Technical scheme of the present invention and its relative theory is described in detail in a specific embodiment.
As shown in Figure 2 A, a kind of high precision oscillator structure 200 suitable for MEMS applications, oscillator structure 200 include
Reference voltage generation module 201, clock signal generating module 202, reference current generation module 203, reference voltage generation module
201 for providing operating voltage, and reference current generation module 203 is used to carry out charge and discharge to clock signal generating module 202.
Reference voltage generation module 201 is connected with clock signal generating module 202, to provide and supply voltage and temperature
Unrelated reference voltage VREF；Reference current generation module 203 is connected with clock signal generating module 202；It is stable to provide
The reference current I unrelated with supply voltage and temperatureREF；Clock signal generating module 202 includes bleeder circuit 204, comparator electricity
Road 205, oscillating circuit 206 and d type flip flop circuit 207, wherein d type flip flop circuit 207 to frequency input signal carry out frequency dividing and
Shaping.
The input terminal of bleeder circuit 204 is connected with reference voltage generation module 201, the output end of bleeder circuit 204 with than
First input end compared with device circuit 205 is connected；
The first input end of comparator circuit 205 is connect with the output end of bleeder circuit 204, and the of comparator circuit 205
Two input terminals are connect with the output end of oscillating circuit 206, and the output end c of comparator circuit 205 is connected with d type flip flop circuit 207；
The input terminal of oscillating circuit 206 is connected with reference current generation module 203, the output end of oscillating circuit 206 with than
The second input terminal compared with device circuit 205 is connected.
Bleeder circuit 204 includes resistor ladder 2041, first switch 2042, second switch 2043, and oscillating circuit 206 includes the
Three switches 2061, the 4th switch 2062 and C capacitances 2063, d type flip flop circuit 207 include d type flip flop 2071.
Reference voltage generation module 201 is connected with clock signal generating module 202, reference voltage generation module 201 and base
Quasi- current generating module 203 is connected.
The first end a of resistor ladder 2041 is connected with the first voltage output end a of reference voltage generation module 201, resistor ladder
2041 second end b is connected with the first end a of first switch 2042, third end c and the second switch 2043 of resistor ladder 2041
First end a is connected, the 4th end d ground connection of resistor ladder 2041.
The first end a of first switch 2042 is connected with the second end b of resistor ladder 2041, the second end b of first switch 2042
It is connected with the first input end a of comparator circuit 205.The first end a of second switch 2043 and the third end c phases of resistor ladder 2042
Even, the second end b of second switch 2043 is connected with the first input end a of comparator circuit 205.
The second end b of the first input end a and first switch 2042a of comparator circuit 205 are connected, comparator circuit 205
First input end a be connected with the second end b of second switch 2043.The output end a of comparator circuit and and d type flip flop circuit
207 are connected, and the signal control third switch 2061 of 205 output end b outputs of comparator circuit is disconnected and is closed, oscillating circuit 205
The signal control third switch 2062 that output end c goes out is disconnected and is closed.
The first end a of third switch 2061 is connected with reference current generation module 203, the second end b of third switch 2061
It is connected with the first end a of the 4th switch 2062, the second end b of third switch 2061 is connected with the first end a of capacitance 2063.
The first end a of 4th switch 2062 is connected with the second end b of third switch 2061, the first end of the 4th switch 2062
A is connected with the first end a of capacitance 2063, and the second end b of the 4th switch 2062 is connected with reference current generation module 203.
The first end a of the capacitance 2063 and first end a of the 4th switch 2062 is connected, the first end a and third of capacitance 2063
The second end b of switch 2061 is connected, the second end b ground connection of capacitance 2063.
The first voltage output end 2014a of reference voltage generation module 201 is connected with the first end a of resistor ladder 2041, base
The first voltage output end 2014a of quasi- voltage generating module 201 and the second voltage input terminal of reference current generation module 203
2031b is connected, the second voltage output end 2014b of reference voltage generation module 201 and the first of reference current generation module 203
Voltage input end 2031a is connected.
The first voltage input terminal 2031a of reference current generation module 203 and the second electricity of reference voltage generation module 201
Output end 2014b is pressed to be connected, the current output terminal 2034a of reference current generation module 203 and the first end a of third switch 2061
It is connected, the current output terminal 2034a of reference current generation module 203 and the second end b of the 4th switch 2062 are connected.
The structural schematic diagram of voltage generating module 201 on the basis of as shown in Figure 2 B, reference current generation module 201 include band
Gap reference circuit（Bandgap Reference）2011, the first operational amplifier 2012a, second operational amplifier 2012b,
Three operational amplifier 2012c, first resistor 2013a, second resistance 2013b, 3rd resistor 2013c, the 4th resistance 2013d,
One voltage output end 2014a and second voltage output end 2014b.First voltage output end 2014a is used for output voltage VREF, the
Two voltage output end 2014b are used for output voltage Vbe2。
One end a of band-gap reference circuit 2011 and the first operational amplifier 2012a in-phase input ends are connected, band-gap reference electricity
The other end b on road 2011 is connected with second operational amplifier 2012b in-phase input ends.One end a of band-gap reference circuit 2011 is used
In output voltage VREF1, one end b of band-gap reference circuit 2011 is for output voltage Vbe1。
The in-phase input end of first operational amplifier 2012a is connected with one end a of band-gap reference circuit 2011, the first operation
The output end of amplifier 2012a is connected with first voltage output end 2014a, the output end of the first operational amplifier 2012a and
The first end a of one resistance 2013a is connected.
The in-phase input end of second operational amplifier 2012b is connected with one end b of band-gap reference circuit 2011, the second operation
The output end of amplifier 2012b is connected with the first end a of 3rd resistor 2013c.
The output end of the first end a of first resistor 2013a and the first operational amplifier 2012a are connected, first resistor 2013a
Second end b be connected with the in-phase input end of third operational amplifier 2012c, the second end b of first resistor 2013a and second electricity
The first end a for hindering 2013b is connected.
The first end a of second resistance 2013b is connected with the in-phase input end of third operational amplifier 2012c, second resistance
The second end b of the first end a and first resistor 2013a of 2013b are connected, the second end b ground connection of second resistance 2013b.
The in-phase input end of third operational amplifier 2012c is connected with the second end b of first resistor 2013a, third operation
The in-phase input end of amplifier 2012c is connected with the first end a of second resistance 2013b, the reverse phase of third operational amplifier 2012c
Input terminal is connected with the second end b of 3rd resistor 2013c, the inverting input and the 4th resistance of third operational amplifier 2012c
The first end a of 2013d is connected, and the output end of third operational amplifier 2012c is connected with second voltage output end 2014b, third
The second end b of the output end of operational amplifier 2012c and the 4th resistance 2013d are connected.
The first end a of 3rd resistor 2013b is connected with the output end of second operational amplifier 2012b, 3rd resistor 2013c
Second end b be connected with the inverting input of third operational amplifier 2012c, the second end b of 3rd resistor 2013c and the 4th electricity
The first end a for hindering 2013d is connected.
The second end b of the first end a and 3rd resistor 2013c of 4th resistance 2013d are connected, and the of the 4th resistance 2013d
One end a is connected with the inverting input of third operational amplifier 2012c, the second end b third operation amplifiers of the 4th resistance 2013d
The output end of device 2012c is connected, and the second end b of the 4th resistance 2013d is connected with second voltage output end 2014b.
As an example, when oscillator works normally, using band-gap reference circuit（Bandgap Reference）2011
Generate a voltage value V unrelated with supply voltage and temperatureREF1And one unrelated with supply voltage but negative temperature coefficient
Specific voltage value Vbe1, and by one group by the first operational amplifier 2012a, second operational amplifier 2012b, third operation
Amplifier 2012c and first resistor 2013a, second resistance 2013b, 3rd resistor 2013c, the 4th resistance 2013d are formed
The adjustable operational amplifier of closed loop gain obtains a stable reference voltage VREFWith the voltage V of temperature coefficient adjustablebe2, wherein
Voltage Vbe2Temperature coefficient and polarity can by be adjusted flexibly the ratio of 3rd resistor 2013c and the 4th resistance 2013d come into
Row variation is suitable for different technique, electricity can be adjusted by adjusting the ratio of first resistor 2013a and second resistance 2013b
Press Vbe2Central point voltage value, by first voltage output end 2014a output voltages VREF, second voltage output end 2014b is defeated
Go out voltage Vbe2。
The structural schematic diagram of current generating module 203 on the basis of Fig. 2 C, in a specific embodiment of the invention, reference current
Generation module 203 includes：First voltage input terminal 2031a, second voltage input terminal 2031b, the first operational amplifier 2032a,
Second operational amplifier 2032b, first resistor 2033a, second resistance 2033b, 3rd resistor 2033c, current mirroring circuit 2034,
Metal-oxide-semiconductor 2035.Current mirroring circuit 2034 is used for output current IREF。
First voltage input terminal 2031a is used for the adjustable voltage V of input temp coefficientbe2, first voltage input terminal 2031a
It is connected with the first end a of first resistor 2033a.
Second voltage input terminal 2031b, for inputting stable reference voltage VREF, second voltage input terminal 2031b and
The in-phase input end of one operational amplifier 2032a is connected.
The first end a of first resistor 2033a is connected with first voltage input terminal 2031a, the second end of first resistor 2033a
B is connected with the first end a of second resistance 2033b, and the second end b of first resistor 2033a and the first operational amplifier 2032a's is anti-
Phase input terminal is connected.
The second end b of the first end a and first resistor 2033a of second resistance 2033b are connected, and the of second resistance 2033b
The inverting input of one end a and the first operational amplifier 2032a are connected, and the second end b of second resistance 2033b and the first operation are put
The output end of big device 2032a is connected.
The inverting input of first operational amplifier 2032a is connected with the second end b of first resistor 2033a, the first operation
The inverting input of amplifier 2032a is connected with the first end a of second resistance 2033b, the same phase of the first operational amplifier 2032a
Input terminal and two voltage input end 2031b are connected, and the of the output end of the first operational amplifier 2032a and second resistance 2033b
Two end b are connected, and the output end of the first operational amplifier 2032a is connected with the in-phase input end of second operational amplifier 2032b.
The in-phase input end of second operational amplifier 2032b is connected with the second end b of second resistance 2033b, the second operation
The output end of the in-phase input end of amplifier 2032b and the first operational amplifier 2032a are connected, second operational amplifier 2032b
Inverting input be connected with the first end a of 3rd resistor 2033c, the output end and metal-oxide-semiconductor of second operational amplifier 2032b
2035 grid is connected.Wherein, the input voltage of the in-phase input end of second operational amplifier is VC。
The first end a of 3rd resistor 2033c is connected with the inverting input of second operational amplifier 2032b, 3rd resistor
The first end a of 2033c is connected with the source electrode of metal-oxide-semiconductor 2035, the second end b ground connection of 3rd resistor 2033c.
The grid of metal-oxide-semiconductor 2035 is connected with the output end of second operational amplifier 2032b, the source electrode of metal-oxide-semiconductor 2035 and
The inverting input of two operational amplifier 2032b is connected, the source electrode of metal-oxide-semiconductor 2035 and the first end a phases of 3rd resistor 2033c
Even, the drain electrode of metal-oxide-semiconductor 2035 is connected with current mirroring circuit 2034.
Current mirroring circuit 2034 is connected with the drain electrode of metal-oxide-semiconductor 2035, and current mirroring circuit 2034 includes current output terminal
2034a。
In normal working conditions, as shown in Figure 2 C, reference current generation module 203 is by reference voltage generation module 201
The voltage V of offerbe2By one group by the first operational amplifier 2032a, second operational amplifier 2032b, first resistor 2033a,
Second resistance 2033b, the operational amplifier of composition is come after adjusting temperature coefficient and polarity so that voltage VCTemperature coefficient and pole
Property is consistent with the temperature coefficient of the resistance R of 3rd resistor 2033c and polarity, obtains a temperature independent electric current I, I=VC/R
=V0/R0, wherein VCExpression formula be VC=V0（1-X*T）, resistance R=R of 3rd resistor 2033c0（1-X*T）, wherein R0It can be with
Regard that constant, size are the resistance values of 3rd resistor 2033c at normal temperatures, V as0Size also with VREFValue and Vbe2Normal
Value under temperature is related.Electric current I can copy many roads after current mirroring circuit 2034 and be used for different circuit modules, often
Current value I all the wayREFCan be the n times of size of primary current I, n can be arbitrary natural number.One stable with electricity
Source voltage and the unrelated electric current of temperature can greatly simplify the design work of other circuit modules.
Reference current generation module 203 as shown in fig. 2 c, by generating a specific temperature coefficient and polar voltage
Vc, it is unrelated with supply voltage and temperature then one to be obtained by the 3rd resistor 2033c of identical polar and temperature coefficient
The technology of electric current I.Such as Fig. 2 B and as shown in Figure 2 C, arbitrary temp coefficient and pole are generated by adjusting operational amplifier and resistance
The technology of the voltage of property.
According to the oscillator 200 that makes of the present invention, the output of reference voltage generation module 201 and supply voltage and temperature without
The voltage value V of passREF, as shown in Figure 2 A, obtained voltage value V is divided through resistor ladder 2041AAnd VB, due to voltage value VREFWith electricity
Source voltage and temperature are unrelated, so VA-VBValue it is also unrelated with supply voltage and temperature.Also, by reference current generation module
The electric current I of 203 outputsREFAlso unrelated with supply voltage and temperature.Comparator circuit 205 export signal frequency expression formula be：f=
1/T=IREF/（2*C*(VA-VB)）, signal output signal frequency after the d type flip flop circuit 207 in oscillator 200 is reduced to
The signal frequency expression formula that original half namely d type flip flop circuit 207 export is：f=【IREF/（2*C*(VA-VB)）】* 0.5,
Therefrom it can be seen that, all variables are all unrelated with supply voltage and temperature in expression formula, so the output frequency of oscillator
Rate is mutually deserved also just unrelated with supply voltage and temperature, to reach the purpose of the present invention, stabilizes the output of oscillator
Frequency.
As shown in Figure 2 A, oscillator 200 uses the reference voltage generation module 201 and base unrelated with temperature and supply voltage
Quasi- current generating module 203 is respectively as partial pressure source and to the current source of capacitor charge and discharge so that the output frequency of oscillator 200
It is almost unrelated with supply voltage and temperature, improve the stability of output frequency.
It, can when there was only the 3rd resistor 2033c of positive temperature coefficient in manufacture craft in a specific embodiment of the invention
With by Fig. 2 B with supply voltage the specific voltage value V of unrelated but negative temperature coefficientbe1It is directly connected to the first electricity in fig. 2 c
Hinder 2033a left end, and by adjusting the ratio of first resistor 2033a and second resistance 2033b be worth to a temperature coefficient with
The voltage V of the matched positive temperature coefficients of 3rd resistor 2033cC.The circuit of the present invention has already passed through flow verification and in height
It is used in the MEMS product of precision, by actual measurement, when mains voltage variations ± 20%, oscillator output frequencies hardly change,
When temperature is from when changing to 100 DEG C for -40 DEG C, the output frequency variation of oscillator can control within ± 1.5%, disclosure satisfy that
The demand of high-precision MEMS product.
Compared with the existing technology for making oscillator, the advantage of the invention is that the output frequency of oscillator is highly stable,
It is almost unrelated with supply voltage and temperature, it can be applied to the occasion of high-precision requirement.The present invention is first by the electricity in resistor ladder
Press VDDIt is substituted for an almost reference voltage V unrelated with voltage temperatureREFTo obtain a stable VA-VBValue, ensure that
The output frequency of oscillator almost with VDDIt is unrelated.Then with a temperature independent constant current IREFTo be filled to capacitance
Electric discharge is so that the output frequency of oscillator is temperature independent.The realization method of the present invention is more convenient and reliable, to technique
Also without particular/special requirement, cost is relatively low.
In conclusion the present invention generates the reference voltage V unrelated with supply voltage and temperature using separate modularREFAnd base
Quasi- electric current IREFIt is supplied to relaxation oscillators to use, so that the stability of the output frequency of oscillator and previous skill
Compared to greatly improving, improved oscillator output frequencies are hardly influenced by the variation of supply voltage and temperature art.The present invention
Production method can be widely applied to various technique platforms, it is convenient and reliable at low cost.
The present invention is illustrated by above-described embodiment, but it is to be understood that, above-described embodiment is only intended to
The purpose of citing and explanation, and be not intended to limit the invention within the scope of described embodiment.In addition people in the art
Member it is understood that the invention is not limited in above-described embodiment, according to the present invention can also make more kinds of modifications and
Modification, these variants and modifications are all fallen within scope of the present invention.
Claims (10)
1. a kind of high precision oscillator structure suitable for MEMS applications, including：Reference voltage generation module, reference current generate
Module and clock signal generating module；
The reference voltage generation module is connected with the clock signal generating module, to provide with supply voltage and temperature without
The reference voltage V of passREF；
The reference current generation module is connected with the clock signal generating module；To provide it is stable with supply voltage and
The unrelated reference current I of temperatureREF；
The clock signal generating module includes bleeder circuit, comparator circuit, oscillating circuit and d type flip flop circuit；
The input terminal of the bleeder circuit is connected with the reference voltage generation module, the output end of the bleeder circuit with it is described
The first input end of comparator circuit is connected；
The output end of the comparator circuit and it is connected with the d type flip flop circuit；
The input terminal of the oscillating circuit is connected with the reference current generation module, the output end of the oscillating circuit with it is described
Second input terminal of comparator circuit is connected；
Wherein, the reference current generation module includes：First voltage input terminal, second voltage input terminal, the 5th resistance, the 6th
Resistance, the 7th resistance, four-operational amplifier, the 5th operational amplifier, metal-oxide-semiconductor, current mirroring circuit, current output terminal, it is described
The adjustable voltage V of first voltage input terminal input temp coefficientbe2, the second voltage input terminal inputs and supply voltage and temperature
Spend unrelated reference voltage VREF, pass through the voltage V for the temperature coefficient adjustable that the first voltage input terminal inputsbe2, described
Five resistance, the 6th resistance, the four-operational amplifier generate arbitrary temp coefficient and polar voltage VC, by adjusting
5th resistance, the 6th resistance ratio be worth to the voltage Vc of a temperature coefficient and polarity and the 7th resistors match,
By with the voltage VCThe 7th resistance of identical polar and temperature coefficient is unrelated with supply voltage and temperature to obtain
Reference current IREF。
2. oscillator structure according to claim 1, which is characterized in that the reference voltage generation module includes band gap base
Quasi- circuit, the first operational amplifier, second operational amplifier, third operational amplifier, first resistor, second resistance, third electricity
Resistance, the 4th resistance, first voltage output end and second voltage output end.
3. oscillator structure according to claim 2, which is characterized in that the band-gap reference circuit and first operation
Amplifier in-phase input end is connected, and the band-gap reference circuit is connected with the second operational amplifier in-phase input end.
4. oscillator structure according to claim 3, which is characterized in that the output end of first operational amplifier and institute
It states first voltage output end to be connected, the output end of first operational amplifier is connected with the first end of the first resistor, institute
The second end for stating first resistor is connected with the in-phase input end of the third operational amplifier, the third operational amplifier it is defeated
Outlet is connected with the second voltage output end, and the second end of the first resistor is connected with the first end of the second resistance,
The second end of the second resistance is grounded.
5. oscillator structure according to claim 3, which is characterized in that the output end of the second operational amplifier and institute
The first end for stating 3rd resistor is connected, the inverting input phase of the second end of the 3rd resistor and the third operational amplifier
Even, the second end of the 3rd resistor is connected with the first end of the 4th resistance, the first end of the 4th resistance with it is described
The inverting input of third operational amplifier is connected, the output of the second end and the third operational amplifier of the 4th resistance
End is connected.
6. oscillator structure according to claim 2, which is characterized in that the band-gap reference circuit generates and supply voltage
The voltage V unrelated with temperatureREF1And the specific voltage V of unrelated but negative temperature coefficient with supply voltagebe1, first electricity
Output end is pressed to export the reference voltage V unrelated with supply voltage and temperatureREF, the second voltage output end output temperature coefficient
Adjustable voltage Vbe2。
7. oscillator structure according to claim 6, which is characterized in that adjust the 3rd resistor and the 4th resistance
Ratio change the voltage Vbe2Temperature coefficient and polarity, adjust the ratio of the first resistor and the second resistance
Adjust the voltage Vbe2Central point voltage value.
8. oscillator structure according to claim 1, which is characterized in that the second voltage input terminal is transported with the described 4th
The in-phase input end for calculating amplifier is connected, and the first voltage input terminal is connected with the first end of the 5th resistance, and described the
The second end of five resistance is connected with the first end of the 6th resistance, and second end and the 4th operation of the 5th resistance are put
The inverting input of big device is connected, the inverting input phase of the first end and the four-operational amplifier of the 6th resistance
Even, the second end of the 6th resistance is connected with the output end of the four-operational amplifier, the second end of the 6th resistance
It is connected with the output end of the four-operational amplifier with the in-phase input end of the 5th operational amplifier.
9. oscillator structure according to claim 1, which is characterized in that the first end and the described 5th of the 7th resistance
The inverting input of operational amplifier is connected, and the first end of the 7th resistance is connected with the source electrode of the metal-oxide-semiconductor, and the described 7th
The second end of resistance is grounded, and the output end of the 5th operational amplifier is connected with the grid of the metal-oxide-semiconductor, the metal-oxide-semiconductor
Drain electrode is connected with the current mirroring circuit, and the current mirroring circuit is connected with the current output terminal, and the current output terminal is used
In the reference current I that output is unrelated with supply voltage and temperatureREF。
10. oscillator structure according to claim 1, which is characterized in that the signal frequency of the d type flip flop circuit output
Expression formula be f=【IREF/(2*C*(VA-VB))】* 0.5, wherein VAAnd VBFor VREFBranch pressure voltage, C is capacitance.
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| CN107317567A (en) * | 2016-04-26 | 2017-11-03 | 成都锐成芯微科技股份有限公司 | The RC oscillating circuits of low-temperature coefficient output frequency |
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| CN101364122A (en) * | 2008-09-16 | 2009-02-11 | 智原科技股份有限公司 | Reference circuit for simultaneously supplying precision voltage and precision current |
| CN101789789A (en) * | 2009-01-22 | 2010-07-28 | 扬智科技股份有限公司 | Generating circuit from reference voltage |
| CN102236359A (en) * | 2010-02-22 | 2011-11-09 | 塞瑞斯逻辑公司 | Band gap reference system not changing with power supply |
| CN102624363A (en) * | 2011-01-28 | 2012-08-01 | 英飞凌科技股份有限公司 | Relaxation oscillator having a supply voltage independent output frequency |
| CN102931913A (en) * | 2012-10-31 | 2013-02-13 | 珠海市杰理科技有限公司 | High-precision oscillator |
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| US7821321B2 (en) * | 2006-01-12 | 2010-10-26 | Micron Technology, Inc. | Semiconductor temperature sensor using bandgap generator circuit |
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|---|---|---|---|---|
| CN101364122A (en) * | 2008-09-16 | 2009-02-11 | 智原科技股份有限公司 | Reference circuit for simultaneously supplying precision voltage and precision current |
| CN101789789A (en) * | 2009-01-22 | 2010-07-28 | 扬智科技股份有限公司 | Generating circuit from reference voltage |
| CN102236359A (en) * | 2010-02-22 | 2011-11-09 | 塞瑞斯逻辑公司 | Band gap reference system not changing with power supply |
| CN102624363A (en) * | 2011-01-28 | 2012-08-01 | 英飞凌科技股份有限公司 | Relaxation oscillator having a supply voltage independent output frequency |
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