CN103501168A - Relaxation oscillator circuit - Google Patents
Relaxation oscillator circuit Download PDFInfo
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- CN103501168A CN103501168A CN201310501775.2A CN201310501775A CN103501168A CN 103501168 A CN103501168 A CN 103501168A CN 201310501775 A CN201310501775 A CN 201310501775A CN 103501168 A CN103501168 A CN 103501168A
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Abstract
The invention provides a relaxation oscillator circuit. The relaxation oscillator circuit comprises a temperature compensation current generating circuit, a temperature compensation voltage generating circuit, a thermometer encoding control module and a relaxation oscillation frequency generating module, wherein the temperature compensation current generating circuit comprises two parasitic triodes, a plurality of resistors and an error amplifier and further comprises cascaded current mirrors, the transmitting electrode of the first parasitic triode is connected with the reverse input end of the error amplifier and the source electrode of an MP3 (Moving Picture Experts Group Audio Layer-3), a transmitting electrode of the second parasitic triode is connected with the homodromous input end of the error amplifier and a source electrode of an MP4 (Mobile Pentium 4) through the first resistor, the cascaded current mirrors adopt an MP1, an MP2, the MP3 and the MP4 to realize a wide oscillation amplitude, and the current of the temperature compensation current generating circuit and the third resistor are utilized by the temperature compensation voltage generating circuit to generate reference voltage during relaxation oscillation and the threshold voltage of capacitors. The design and the configuration of the relaxation oscillator circuit are realized by the circuit structures and the combination thereof, so that the remarkable effects of facilitating massive production and lowering product cost are achieved.
Description
Technical field
The invention provides a kind of CMOS integrated circuit, refer in particular to the manageable relaxation oscillator circuit of a kind of low cost, high accuracy and frequency.
Background technology
On sheet, oscillator is the indispensable part of low cost integrated circuit system (SOC), be used to provide the needed clock signal of respective digital circuit, in order to guarantee the reliability of system works, need on compensating plate clock frequency with the variation of temperature and supply voltage.The pierce circuit of common CMOS process compatibility has RC oscillator, electric current/capacitor relaxation oscillator etc.Wherein, relaxation oscillator is easily realized 50% duty ratio, easily compensates the output frequency drift, therefore is widely used.
The traditional method of relaxation oscillator frequency stability compensation is many, typically has:
1. described in " a kind of RC pierce circuit of eliminating temperature and voltage influence " of prior art, the reference voltage U=i*R1 of oscillator, charging current I=i*R2/R3, the temperature coefficient of the current i in the prior art has determined the temperature coefficient of I, but the temperature coefficient of reference voltage is determined jointly by the temperature coefficient of i and the temperature coefficient of resistance R 1, therefore there is no matching relationship between reference voltage U and charging current I, in the pierce circuit practical work process, variation with temperature is larger, haves much room for improvement;
2. " temperature-compensation circuit and the method " of prior art, the charging current Ich=Vref/ of relaxation oscillator (Rntc+Rptc), wherein, Vref is band gap reference voltage, Rntc is negative temperature coefficient resister, Rptc is positive temperature coefficient resistor, offsets to realize the charging current of temperature-compensating by the temperature coefficient of dissimilar resistance, does not provide the reference voltage producing method of oscillator in patent.Because resistance on dissimilar sheet can not be accomplished to mate preferably, and the reference voltage of relaxation oscillator is directly related with the vibration output frequency, therefore the oscillator frequency in this patent is apparent in view with process deviation, variations in temperature, be applicable to theoretical research, be difficult in actual applications batch production.
Summary of the invention
For solving the problems of the technologies described above, the object of the present invention is to provide a kind of relaxation oscillator circuit, the pierce circuit of temperature and voltage compensation on its bonding pad, reached that Product Precision is high, the manageable good result of frequency, effectively solved the batch production product and had inconsistent technical problem, also for the reduction product cost, played good result simultaneously.
For achieving the above object, a kind of relaxation oscillator circuit of the present invention, comprise temperature compensation module, thermometer coding control module and relaxation oscillation frequency generation module, described temperature compensation module comprises that temperature-compensated current produces circuit and temperature-compensated voltage produces circuit, wherein: this temperature-compensated current produces circuit and comprises two parasitic triodes, some resistance and error amplifier, wherein: the emitter of parasitic triode one is connected with the source electrode of the reverse input end of this error amplifier and MP3, the emitter of parasitic triode two is connected with the output in the same way of this error amplifier and the source electrode of MP4 by resistance one, and comprise and adopt MP1, MP2, MP3 and MP4 realize the cascade current mirror of the wide amplitude of oscillation, and described temperature-compensated voltage produces electric current and the reference voltage in resistance three generation relaxation oscillations and the threshold voltage of electric capacity that circuit utilizes this temperature-compensated current generation circuit.
In the present embodiment, described some resistance is crystal silicon resistance, and comprises resistance two and resistance four, and resistance and size that described resistance one, two, three and four is same types are identical.
In the present embodiment, described thermometer coding control module comprises the basic logic gate circuit of realizing the dull adjusting of output frequency.
In the present embodiment, described relaxation oscillation frequency generation module comprises symmetrical charge-discharge circuit and rest-set flip-flop.
In the present embodiment, the total temperature scope of described relaxation oscillation frequency generation module is between-40 ℃ ~ 125 ℃.
In the present embodiment, the drift of the output frequency of described relaxation oscillation frequency generation module is less than 5%.
The present invention compared with prior art, its beneficial effect: the one, simple in structure, be easy to the batch production; The 2nd, can keep the consistency of product in batch production; The 3rd, the frequency characteristic of product is stable; The 4th, can effectively reduce production costs.
The accompanying drawing explanation
Fig. 1 is the frame structure schematic diagram of the present invention's preferred embodiment.
Fig. 2 is the structural representation that in Fig. 1, temperature-compensated current produces circuit.
Fig. 3 is the structural representation that in Fig. 1, temperature-compensated voltage produces circuit.
Fig. 4 is the charging current Ich schematic diagram of thermometer coding control module in Fig. 1.
Fig. 5 is the structural representation of relaxation oscillation frequency generation module in Fig. 1.
Embodiment
By the technology contents, the structural feature that describe the present invention in detail, reached purpose and effect, below hereby exemplify embodiment and coordinate accompanying drawing to be explained in detail.
Refer to Fig. 1 also in conjunction with consulting shown in Fig. 2 and Fig. 3, a kind of relaxation oscillator circuit, comprise temperature compensation module 10, thermometer coding control module 20 and relaxation oscillation frequency generation module 30, wherein: described temperature compensation module 10 comprises that temperature-compensated current produces circuit 11 and temperature-compensated voltage produces circuit 12, wherein:
Please in conjunction with consulting shown in Fig. 2 and Fig. 3, described temperature-compensated current produces circuit 11, comprise parasitic triode, resistance, error amplifier and CMOS, wherein: producing temperature-compensated current is by parasitic triode BE knot negative temperature coefficient voltage, PTAT positive temperature coefficient voltage, non-silication P+ polysilicon resistance obtains, particularly: the base stage and the emitter voltage VBE (Q_N1) that utilize the parasitic substrate PNP triode in common CMOS process, VBE (Q_N8), this voltage varies with temperature and is negative temperature coefficient, and VBE (Q_N1) presents positive temperature coefficient with the difference voltage of VBE (Q_N8).Therefore, negative temperature parameter current is Intc=VBE (Q_N1)/R2, positive temperature coefficient electric current I ptc=(VBE (Q_N1)-VBE (Q_N8))/R1, wherein R1 and R2 are non-silication P+ polysilicon resistances (little negative temperature coefficient), relaxation oscillator charging current Ich=Iptc+Intc after temperature-compensating, and the EAMP error amplifier plays clamping action, the voltage at R2 and R3 two ends equates and equals VBE (Q_N1), the voltage at R1 two ends equals VBE (Q_N1)-VBE (Q_N8), R2=R3 in this circuit, so the electric current that R1/R2/R3 is corresponding is respectively: I (R2)=I (R3)=VBE (Q_N1)/R2=VBE (Q_N1)/R3, I (R1)=(VBE (Q_N1)-VBE (Q_N8))/R1.In CMOS technique, the voltage of triode, current relationship are: Ic=Is* (exp (VBE/VT)), so VBE (Q_N1)-VBE (Q_N8)=VT*ln (n), VT=KT/q wherein, the ratio of the emitter region area that n is Q_N1 and Q_N8 triode.To sum up relation has: Ich0=I (MP2)=I (MP1)=I (R3)+I (R1)=VBE (Q_N1)/R3+ (VT*ln (n))/R1, VBE in this formula (Q_N1) varies with temperature and shows as negative temperature coefficient, VT varies with temperature and shows as positive temperature coefficient, therefore can guarantee that by the device parameters in design circuit Ich0 shows as zero-temperature coefficient at T=27 ℃, reaches the purpose of temperature-compensating.In addition, this circuit adopts MP1/MP2/MP3/MP4 to realize the cascade current mirror of the wide amplitude of oscillation, has improved Power Supply Rejection Ratio, makes the supply voltage size can ignore on the impact of temperature-compensated current Ich0; Shown in Fig. 3, described temperature-compensated voltage produces circuit 12, wherein: the size of current of this R1 is positive temperature coefficient electric current I (PTAT)=(VT*ln (n))/R1, the size of current of R2 and R3 is negative temperature parameter current I (VBE (Q_N1)/R2)=I (VBE (Q_N1)/R3), flow through the size of current Ich0=I (R1) of R4+I (R2), this electric current is zero-temperature coefficient electrical current.In circuit, R1/R2/R3/R4 adopts the less non-silication P+ polysilicon resistance of negative temperature temperature coefficient, and Vcmp=Ich0*R4, therefore Vcmp is the voltage through the slightly negative temperature coefficient of temperature-compensating, size by R4 resistance is set the threshold voltage that Vcmp voltage is less than mos capacitance, meets the requirement of follow-up relaxation oscillator circuit.
Please in conjunction with consulting shown in Fig. 4, described thermometer coding control module 20 is to control the circuit of Ich size of current, it is the frequency drift that the regulation of electrical circuit process corner (corner) causes, particularly, it is the advantage of utilizing the thermometer coding monotonicity good, can be precisely controlled in conjunction with the oscillator centre frequency be provided with, because output frequency is determined jointly by charging and discharging currents and mos capacitance, therefore can increase temperature and the voltage characteristic that the thermometer coding figure place reaches desired output frequency precision and do not affect frequency; In the present embodiment, din1 and din0 are digital control input binary codes, and ctl2, clt1 and clt0 are thermometer coding output control signals, the non-output of logic OR that wherein ctl0 is din1 and din0, the logic negate output that ctl1 is din1, the non-output of the logical AND that ctl2 is din1 and din0; In the present embodiment, the image current that the Ich1/Ich2/Ich3 electric current is aforementioned temperature offset current Ich0, therefore also have zero-temperature coefficient.Said temperature meter code signal cltl2/ctl1/ctl0 controls corresponding MOS switch, thereby has realized the dullness of Ich charging current is controlled.Can select corresponding binary system control code figure place according to required precision, thereby realize the accurate control of oscillator frequency.
Please in conjunction with consulting shown in Fig. 5, described relaxation oscillation frequency generation module 30, adopt traditional symmetrical charging-discharging structure and rest-set flip-flop to realize, due to the charge and discharge process full symmetric of electric current to mos capacitance, therefore can well control the duty ratio of clock signal, and clock signal duty cycle is most important for digital circuitry.For example: assumed initial state vc1=1, vc2=0, MP10 and MN11 transistor turn-off, and MN10 and MP11 transistor are opened, and zero-temperature coefficient electrical current Ich is by MP11 to electric capacity MCAP2 charging, and MCAP1 electric capacity discharges into 0 current potential by the MN10 transistor.When the voltage vo2 on MCAP2 electric capacity reaches temperature-compensated voltage Vcmp, comparator is exported 1 level, and now vo1 voltage is lower than Vcmp voltage, and its corresponding comparator is output as 0 level.The rest-set flip-flop be comprised of NOR gate can obtain: vc1=0, and vc2=1, now MP10 and MN11 open, MP11 and MN10 turn-off, and zero-temperature coefficient electrical current Ich charges to MOSCAP1 by MP10, and MCAP2 discharges over the ground by MN11, analysis before repeating has: vc1=1, vc2=0.Circuit shown in Fig. 5 is the process generation oscillating clock signal that constantly circulates according to the above analysis.Charge and discharge process full symmetric due to this circuit, therefore the duty ratio of output signal is 50%, and in addition, the time that discharges and recharges is determined by zero-temperature coefficient electrical current Ich and temperature-compensated voltage Vcmp, therefore temperature, supply voltage are smaller on the impact of output frequency, are applicable to the application of SOC (system on a chip) clock.
In sum, only, for the present invention's preferred embodiment, with this, do not limit protection scope of the present invention, all equivalences of doing according to the scope of the claims of the present invention and description change and modify, within being all the scope that patent of the present invention contains.
Claims (6)
1. a relaxation oscillator circuit, comprise temperature compensation module, thermometer coding control module and relaxation oscillation frequency generation module, described temperature compensation module comprises that temperature-compensated current produces circuit and temperature-compensated voltage produces circuit, it is characterized in that: this temperature-compensated current produces circuit and comprises two parasitic triodes, some resistance and error amplifier, wherein: the emitter of parasitic triode one is connected with the source electrode of the reverse input end of this error amplifier and MP3, the emitter of parasitic triode two is connected with the output in the same way of this error amplifier and the source electrode of MP4 by resistance one, and comprise and adopt MP1, MP2, MP3 and MP4 realize the cascade current mirror of the wide amplitude of oscillation, and described temperature-compensated voltage produces electric current and the reference voltage in resistance three generation relaxation oscillations and the threshold voltage of electric capacity that circuit utilizes this temperature-compensated current generation circuit.
2. relaxation oscillator circuit as claimed in claim 1, it is characterized in that: described some resistance is crystal silicon resistance, and comprises resistance two and resistance four, resistance and size that described resistance one, two, three and four is same types are identical.
3. relaxation oscillator circuit as claimed in claim 1 is characterized in that: described thermometer coding control module comprises and realizes the dull basic logic gate circuit of regulating of output frequency.
4. relaxation oscillator circuit as claimed in claim 1, it is characterized in that: described relaxation oscillation frequency generation module comprises symmetrical charge-discharge circuit and rest-set flip-flop.
5. relaxation oscillator circuit as claimed in claim 4, it is characterized in that: the total temperature scope of described relaxation oscillation frequency generation module is between-40 ℃ ~ 125 ℃.
6. relaxation oscillator circuit as claimed in claim 5 is characterized in that: the output frequency drift of described relaxation oscillation frequency generation module is less than 5%.
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| CN201310501775.2A CN103501168A (en) | 2013-10-23 | 2013-10-23 | Relaxation oscillator circuit |
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| CN201310501775.2A CN103501168A (en) | 2013-10-23 | 2013-10-23 | Relaxation oscillator circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104410421A (en) * | 2014-11-11 | 2015-03-11 | 昆腾微电子股份有限公司 | A capacitance compensation device and method for a sampling circuit |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6229403B1 (en) * | 1998-08-06 | 2001-05-08 | Yamaha Corporation | Voltage-controlled oscillator |
| CN101977035A (en) * | 2010-11-19 | 2011-02-16 | 无锡灿星科技有限公司 | Temperature compensation offset eliminated RC oscillator |
| CN102640418A (en) * | 2009-11-30 | 2012-08-15 | 利他半导体股份有限公司 | Oscillator circuit which compensates for external voltage supply, temperature and process |
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2013
- 2013-10-23 CN CN201310501775.2A patent/CN103501168A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6229403B1 (en) * | 1998-08-06 | 2001-05-08 | Yamaha Corporation | Voltage-controlled oscillator |
| CN102640418A (en) * | 2009-11-30 | 2012-08-15 | 利他半导体股份有限公司 | Oscillator circuit which compensates for external voltage supply, temperature and process |
| CN101977035A (en) * | 2010-11-19 | 2011-02-16 | 无锡灿星科技有限公司 | Temperature compensation offset eliminated RC oscillator |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104410421A (en) * | 2014-11-11 | 2015-03-11 | 昆腾微电子股份有限公司 | A capacitance compensation device and method for a sampling circuit |
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Application publication date: 20140108 |