CN203071868U - Correctable and adjustable high-precision relaxation oscillator - Google Patents
Correctable and adjustable high-precision relaxation oscillator Download PDFInfo
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- CN203071868U CN203071868U CN 201320018785 CN201320018785U CN203071868U CN 203071868 U CN203071868 U CN 203071868U CN 201320018785 CN201320018785 CN 201320018785 CN 201320018785 U CN201320018785 U CN 201320018785U CN 203071868 U CN203071868 U CN 203071868U
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Abstract
The utility model discloses a correctable and adjustable high-precision relaxation oscillator. The correctable and adjustable high-precision relaxation oscillator comprises an oscillation generator, a high-precision current bias generator, a voltage regulator, and a driving and output part, wherein the high-precision current bias generator provides bias for a constant current source in the oscillation generator, and the voltage regulator generates two threshold levels for a comparator in the oscillation generator; and the oscillation generator generates oscillation waveform through utilizing the charging and discharging of a capacitor and provides the oscillation waveform to the driving and output part. The correctable and adjustable high-precision relaxation oscillator of the utility model has the advantages that through the realization of high precision bias current and the correction and adjustment of a register which performs comparison on the threshold levels, process deviations and changes of the frequency of the oscillator when power source voltage or environment temperature changes can be decreased, such that corrected frequency values can satisfy accuracy requirements of design.
Description
Technical field
The utility model relates to integrated circuit fields, relates in particular to a kind of overriding high accuracy relaxation oscillator, can be applicable to the reference clock of SOC SOC (system on a chip).
Background technology
Oscillator is the important component part of many electronic systems.Relaxation oscillator claims to discharge and recharge oscillator again, is by alternately discharge and recharge to carry out work between two threshold levels that electric capacity has been set in circuit.In this manner, quasi stationary state of circuit elder generation's tension and relaxation reaches certain threshold level position until it; Then, circuit switches and tension and relaxation reaches another threshold value to another quasi stationary state until it and switches back first quasi stationary state again.This process constantly continues by this form.
The basic topological structure of relaxation oscillator as shown in Figure 1.Wherein S1 represents control switch, and the COMP representative comprises the comparator of two compare threshold level.When switch S 1 disconnects, capacitor C 1 charging, the comparator input voltage raises; After arriving a threshold voltage, output change state, switch S 1 closure, electric capacity begins discharge, and capacitance voltage reduces, until another threshold voltage of comparator.The output frequency size of oscillator is determined jointly by R1, R2, C1 and comparator threshold level.
On the basis of Fig. 1 basic structure multiple circuit implementation is arranged, such as charging to electric capacity by resistance, also can charge to electric capacity by constant-current source; COMP can be realized by two comparators, also can be realized by a comparator.And no matter which kind of implementation, the frequency of relaxation oscillator is subjected to the device properties influence very big, therefore faces a problem, and namely when process deviation, supply voltage and ambient temperature changed, bigger departing from might take place in the output frequency value of oscillator.For the occasion that requires frequency accurately to use, then must carry out high-precision design and suppress the variation that PVT causes, add that in case of necessity the mode of repairing accent adjusts.
The utility model content
The utility model has overcome shortcoming of the prior art, and a kind of overriding high accuracy relaxation oscillator is provided, and adopts constant-current source to the mode of capacitor charge and discharge, and constant-current source adopts the very little bias current of high-precision variation simultaneously; Two threshold voltages of comparator are provided by voltage adjuster, in circuit, be provided with the accent of repairing of resistance, thereby be used for regulating the threshold voltage adjustment oscillator frequency of comparator, even parameter variation situation greatly occurs, also can be adjusted to design load by repairing; Adopted register configuration to repair the mode of accent repairing the accent mode.
The technical solution of the utility model is: a kind of overriding high accuracy relaxation oscillator, comprise clapp oscillator, high-precision current biasing generator, voltage adjuster and driving and output, wherein: high-precision current biasing generator provides biasing for the constant current source in the clapp oscillator, and voltage adjuster is that the comparator in the clapp oscillator generates two threshold levels; Clapp oscillator utilizes capacitor charge and discharge to produce waveform and offers driving and output.
Common-source common-gate current mirror structure, electric capacity, three metal-oxide-semiconductor switches (140,141,142) and a comparator that described clapp oscillator comprises the common-source common-gate current mirror structure that is made of four PMOS pipes (110,111,112,113), is made of four NMOS pipe (120,121,122,123); Wherein: PMOS pipe (112,113) constitutes constant current source, and PMOS pipe (110,111) provides current offset for the NMOS pipe; It is heavy that NMOS pipe (121,123) constitutes constant current, and NMOS pipe (120,122) provides biasing; Described constant current source and constant current sink in the waveform production process electric capacity are discharged and recharged; Metal-oxide-semiconductor switch (140) is connected between the biasing (125) and ground that NMOS pipe (120,122) provides, heavy the opening and turn-off of control constant current; Metal-oxide-semiconductor switch (141) is connected between high threshold level and the comparator anode, and metal-oxide-semiconductor switch (142) is connected between the gentle comparator negative terminal of low-threshold power, and electric capacity switches between high and low two threshold levels when being used for control generator work.
Described high-precision current biasing generator is grouped into by self biased operational amplifier and high-precision current generating unit, wherein: self biased operational amplifier comprises one-level PMOS pipe input amplifier structure and common-source stage structure for amplifying, described common-source stage structure for amplifying output voltage produces part to high-precision current and carries out clamper, for grid provides voltage bias, this voltage bias also is simultaneously the output of high-precision current biasing generator simultaneously; High-precision current generating unit branch comprises common-source common-gate current mirror, and PNP pipe (261), PNP pipe (262) and resistance (271) generate the PTAT electric current that is directly proportional with temperature by amplifier positive-negative input end clamper; Resistance (281) and resistance (282) are got similar resistance, are connected on the amplifier positive-negative input end, generate the CTAT electric current that is inversely proportional to temperature at branch road.
Described high-precision current produces part and also comprises PNP pipe (263), resistance (291) and resistance (292).
Described voltage adjuster comprises band-gap reference circuit, operational amplifier, output driving tube and repaiies and transfer the resistance switch network that wherein: described operational amplifier makes the positive terminal voltage of amplifier equal the reference circuit output voltage of amplifier negative terminal by clamper; The output driving tube is used for providing electric current; Repair and transfer the resistance switch network output needed high threshold level of clapp oscillator and lower threshold level.
Described high threshold level and lower threshold level change by the external register deploy switch.
Described driving and output are used for improving the driving force of the waveform that has generated by inverter (410 and 412) cascade.
Compared with prior art, the utility model has the advantages that: repair accent by the realization of high accuracy bias current and the register of compare threshold level, the frequency change of oscillator in the time of can reducing process deviation, supply voltage or ambient temperature and change makes the revised value of frequency satisfy the required precision of design.
Description of drawings
The utility model will illustrate by example and with reference to the mode of accompanying drawing, wherein:
Fig. 1 is the schematic diagram of relaxation oscillator prior art;
Fig. 2 is electrical block diagram of the present utility model;
Fig. 3 is the structural representation of high-precision current biasing generator in the utility model;
Fig. 4 is the structural representation that band is repaiied the voltage adjuster of accent in the utility model;
Fig. 5 is the sequential chart of portion waveshape in the utility model.
Embodiment
A kind of overriding high accuracy relaxation oscillator as shown in Figure 2, comprises clapp oscillator 100, high-precision current biasing generator 200, and voltage adjuster 300 drives and output 400.Wherein: clapp oscillator 100 utilizes capacitor charge and discharge to produce waveform, high-precision current biasing generator 200 provides biasing for the constant current source in the clapp oscillator, voltage adjuster 300 generates two threshold levels of comparator, register configuration is repaiied to transfer and is also included within this part the inside, and driving and output 400 improve driving force and the output waveform of oscillator wave by chain of inverters.
Four PMOS pipe 110,111,112,113 has constituted the common-source common-gate current mirror structure of PMOS pipe, and the biasing 231(that their grid connects 200 outputs of high-precision current biasing generator respectively is pbias1) and the 232(that setovers be pbias2).PMOS pipe 112(M3 wherein) and 113(M4) constitute constant current source, PMOS manages 110(M1) and 111(M2) provide current offset for the NMOS pipe.
Four NMOS pipe 120,121,122,123 has constituted the common-source common-gate current mirror structure of NMOS pipe, wherein NMOS pipe 120(M5) and 122(M6) provide biasing, NMOS manage 121(M7) and 123(M8) constitute constant current and sink.Constant current source and constant current sink in the waveform production process capacitor C 1 are discharged and recharged.The order of magnitude of the heavy electric current of constant current source and constant current can influence the size of oscillator output frequency; The size of current relative value then can determine the duty ratio of output waveform.Be under the situation of current source current twice at the heavy electric current of electric current, duty ratio just is 50%.
Metal-oxide-semiconductor switch 140(S1) be connected on the biasing 125(nbias1 that NMOS pipe 120 and 122 produces) and ground between, heavy the opening and turn-off of control constant current; Metal-oxide-semiconductor switch 141(S2) be connected on high threshold level 341(VH) and comparator anode 151 between, metal-oxide-semiconductor switch 142(S3) be connected on lower threshold level 342(VL) and comparator negative terminal 152 between, electric capacity switches between two threshold levels during control generator work, and high threshold level VH and lower threshold level VL are produced by voltage adjuster 300.
Charge and discharge capacitance 130(C1) connects P pipe constant current source, the heavy and comparator negative terminal 152 of N pipe constant current, carried out discharging and recharging of electric charge.
The concrete course of work of clapp oscillator is described below: when electric capacity 130 is also uncharged, comparator 150 is output as high level, making what insert the comparator anode by control switch 142 is high threshold level VH, switch 140 conductings simultaneously, thereby turn-offed the heavy electric current of N pipe constant current, this moment is with the electric current of P pipe constant current source
I Electric capacity 130 is charged; When voltage on the electric capacity surpassed VH, comparator output became low level, and switch 140 turn-offs, and the heavy work of N pipe constant current is if the heavy electric current of electric current is 2
I, then electric capacity 130 will be with electric current
IDischarge, that inserts the comparator anode simultaneously has also become lower threshold level VL, is reduced to VL up to the capacitance voltage value and deflects again when following.
The frequency of this oscillator depends on the poor of capacitance size, charging and discharging currents and high lower threshold level.Therefore designed the current with high accuracy biasing, to reduce supply voltage and temperature to the influence of frequency, the current offset structure is seen Fig. 3; Deviation for technology etc. then is returned to design load by repair the mode of heightening lower threshold level in voltage adjuster with the frequency values adjustment, and structure is seen Fig. 4.
Fig. 3 is the circuit structure diagram of high-precision current biasing generator 200, produces part 250 by self biased operational amplifier 210 and high-precision current and forms.
In the self biased operational amplifier 210, metal-oxide-semiconductor 211,212,213,214,219 and 220 has constituted the one-level PMOS pipe input amplifier structure that the technical staff knows; Metal-oxide-semiconductor 215,216, the 217 and 218 common-source stage structure for amplifying of forming have generated voltage bias 231(pbias1) and voltage bias 232(pbias2), these two voltage bias have played high-precision current generation part 250 have been carried out the effect of clamper, simultaneously for grid provides voltage bias, voltage bias 231(pbias1) and voltage bias 232(pbias2) also be simultaneously the output of high-precision current biasing generator 200.
High-precision current produces in the part 250, and PMOS pipe 251 to 256 has constituted common-source common-gate current mirror, can reduce the mismatch of bias current, suppresses mains voltage variations simultaneously to the influence of electric current.PNP manages 261(Q1), PNP manages 262(Q2) and resistance 271(R1) by amplifier positive-negative input end clamper, generated the PTAT electric current that is directly proportional with temperature that the technical staff knows, current value equals △ VBE divided by the resistance value of R1.Resistance 281(R3) and resistance 282(R2) get similar resistance, be connected on the amplifier positive-negative input end equally, generated the CTAT electric current that is inversely proportional to temperature at branch road, current value equals VBE divided by the resistance value of R2 or R3.By suitable resistance value is set, with PTAT electric current and CTAT current summation, can obtain changing very little electric current through single compensation with temperature coefficient.In order further to reduce temperature coefficient, introduced nonlinear compensation, PNP manages 263(Q3), resistance 291(R4) and resistance 292(R5) namely played the effect that reduces nonlinear terms.
By voltage bias 231(pbias1) and voltage bias 232(pbias2), high-precision current bias generator 200 is exportable with supply voltage and the very little bias current of variations in temperature.Because the electric current absolute value is directly related with resistance value, when resistance process corner deviation, bias current still has certain variation, thereby influences the variation of output frequency.Therefore heighten lower threshold level and come the frequency of amendment influence by repairing, repair and transfer part in voltage adjuster 300, circuit structure as shown in Figure 4.
Fig. 4 is the electrical block diagram of voltage adjuster 300, comprises band-gap reference circuit 310, operational amplifier 320, output driving tube 330 and repaiies accent resistance switch network 340.
Operational amplifier 320 makes the positive terminal voltage 322 of amplifier equal the reference circuit output voltage 321 of amplifier negative terminal by clamper, and output driving tube 330 provides enough electric currents.Wherein the circuit structure of band-gap reference circuit 310 and operational amplifier 320 no longer describes in detail at this.
Repair and transfer resistance switch network 340 output clapp oscillators 100 needed high threshold level 341 and lower threshold level 342, and can change the value of threshold level by the external register deploy switch.In Fig. 4, high threshold level voltage value 341 is fixing, and lower threshold level magnitude of voltage 342 can dispose by switch.Also can be as required fixing lower threshold level, configuration high threshold level; Perhaps two threshold levels are configured respectively.Figure place and the switch number of configuration depend on the accent scope of repairing, required precision and take resource consideration etc.Adopting 16 configurations among Fig. 4, OSCTRIM[15:0] 16 control lines 345 are connected respectively to the grid of switch S 0 to S15, and externally register control has and only has a switch conduction down, thereby be that lower threshold level 342 disposes required voltage values.Resistance value from R3 to R17 equates, so the configuration of voltage such as is at step change.
For reducing output port number, OSCTRIM[15:0] can connect 4 lines-16 line decoder for decoding before the control line 345, port number is reduced to 4, implementation procedure specifically no longer describes in detail.
As shown in Figure 2, driving and output 400 improve the driving force of the waveform that has generated by inverter 410 and 412 cascades, are output as 430(CLK).
Fig. 5 has reflected the sequential chart of portion waveshape, comprises the waveform of comparator 150 anodes 151 and negative terminal 152, and the waveform of oscillator output 430.
Claims (7)
1. overriding high accuracy relaxation oscillator, it is characterized in that: comprise clapp oscillator, high-precision current biasing generator, voltage adjuster and driving and output, wherein: high-precision current biasing generator provides biasing for the constant current source in the clapp oscillator, and voltage adjuster is that the comparator in the clapp oscillator generates two threshold levels; Clapp oscillator utilizes capacitor charge and discharge to produce waveform and offers driving and output.
2. a kind of overriding high accuracy relaxation oscillator according to claim 1 is characterized in that: common-source common-gate current mirror structure, electric capacity, three metal-oxide-semiconductor switches (140,141,142) and a comparator that described clapp oscillator comprises the common-source common-gate current mirror structure that is made of four PMOS pipes (110,111,112,113), is made of four NMOS pipe (120,121,122,123); Wherein: PMOS pipe (112,113) constitutes constant current source, and PMOS pipe (110,111) provides current offset for the NMOS pipe; It is heavy that NMOS pipe (121,123) constitutes constant current, and NMOS pipe (120,122) provides biasing; Described constant current source and constant current sink in the waveform production process electric capacity are discharged and recharged; Metal-oxide-semiconductor switch (140) is connected between the biasing (125) and ground that NMOS pipe (120,122) provides, heavy the opening and turn-off of control constant current; Metal-oxide-semiconductor switch (141) is connected between high threshold level and the comparator anode, and metal-oxide-semiconductor switch (142) is connected between the gentle comparator negative terminal of low-threshold power, and electric capacity switches between high and low two threshold levels when being used for control generator work.
3. a kind of overriding high accuracy relaxation oscillator according to claim 1, it is characterized in that: described high-precision current biasing generator is grouped into by self biased operational amplifier and high-precision current generating unit, wherein: self biased operational amplifier comprises one-level PMOS pipe input amplifier structure and common-source stage structure for amplifying, described common-source stage structure for amplifying formation voltage biasing produces part to high-precision current and carries out clamper, for grid provides voltage bias, voltage bias also is simultaneously the output of high-precision current biasing generator simultaneously; High-precision current generating unit branch comprises common-source common-gate current mirror, and PNP pipe (261), PNP pipe (262) and resistance (271) generate the PTAT electric current that is directly proportional with temperature by amplifier positive-negative input end clamper; Resistance (281) and resistance (282) are got similar resistance, are connected on the amplifier positive-negative input end, generate the CTAT electric current that is inversely proportional to temperature at branch road.
4. a kind of overriding high accuracy relaxation oscillator according to claim 3 is characterized in that: described high-precision current produces part and also comprises PNP pipe (263), resistance (291) and resistance (292).
5. a kind of overriding high accuracy relaxation oscillator according to claim 1, it is characterized in that: described voltage adjuster comprises band-gap reference circuit, operational amplifier, output driving tube and repaiies and transfer the resistance switch network that wherein: described operational amplifier makes the positive terminal voltage of amplifier equal the reference circuit output voltage of amplifier negative terminal by clamper; The output driving tube is used for providing electric current; Repair and transfer the resistance switch network output needed high threshold level of clapp oscillator and lower threshold level.
6. a kind of overriding high accuracy relaxation oscillator according to claim 5, it is characterized in that: described high threshold level and lower threshold level change by the external register deploy switch.
7. a kind of overriding high accuracy relaxation oscillator according to claim 1 is characterized in that: described driving and output are used for improving the driving force of the waveform that has generated by inverter (410 and 412) cascade.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320018785 CN203071868U (en) | 2013-01-15 | 2013-01-15 | Correctable and adjustable high-precision relaxation oscillator |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320018785 CN203071868U (en) | 2013-01-15 | 2013-01-15 | Correctable and adjustable high-precision relaxation oscillator |
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| CN203071868U true CN203071868U (en) | 2013-07-17 |
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| CN 201320018785 Expired - Fee Related CN203071868U (en) | 2013-01-15 | 2013-01-15 | Correctable and adjustable high-precision relaxation oscillator |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104143979A (en) * | 2014-02-25 | 2014-11-12 | 上海菱沃铂智能技术有限公司 | High-precision high-frequency ring oscillator circuit |
| CN108572034A (en) * | 2018-04-24 | 2018-09-25 | 电子科技大学 | A kind of temperature sensor circuit of embedded clock |
-
2013
- 2013-01-15 CN CN 201320018785 patent/CN203071868U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104143979A (en) * | 2014-02-25 | 2014-11-12 | 上海菱沃铂智能技术有限公司 | High-precision high-frequency ring oscillator circuit |
| CN104143979B (en) * | 2014-02-25 | 2018-03-06 | 上海菱沃铂智能技术有限公司 | A kind of high-precision high frequency ring oscillator circuit |
| CN108572034A (en) * | 2018-04-24 | 2018-09-25 | 电子科技大学 | A kind of temperature sensor circuit of embedded clock |
| CN108572034B (en) * | 2018-04-24 | 2020-11-13 | 电子科技大学 | Temperature sensor circuit with built-in clock |
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| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130717 Termination date: 20190115 |