CN204633751U - A kind of ring oscillator circuit - Google Patents
A kind of ring oscillator circuit Download PDFInfo
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- CN204633751U CN204633751U CN201520286559.5U CN201520286559U CN204633751U CN 204633751 U CN204633751 U CN 204633751U CN 201520286559 U CN201520286559 U CN 201520286559U CN 204633751 U CN204633751 U CN 204633751U
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- voltage
- ring oscillator
- temperature coefficient
- circuit
- negative temperature
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Abstract
The utility model discloses a kind of ring oscillator circuit, for realizing temperature-compensating with stabilizing clock frequency, it is characterized in that, comprising: a benchmark bandgap cell, for receiving a supply voltage and exporting the negative temperature coefficient voltage be inversely proportional to temperature and a bias voltage; One linear voltage stabilization unit, for receiving this negative temperature coefficient voltage and this bias voltage, exports the negative temperature coefficient voltage after an amplification; One ring oscillation unit, this ring oscillation unit receives the negative temperature coefficient voltage after this amplification as operating voltage, and this clock frequency of stable output; One level conversion unit, this level conversion unit receive this bias voltage for by the operating voltage of this ring oscillation unit by the negative temperature coefficient voltage transitions after this amplification for this supply voltage.
Description
Technical field
The utility model relates to a kind of clock oscillator, particularly relates to a kind ofly can realize temperature-compensating with the ring oscillator circuit of stabilized frequency.
Background technology
Utilize the CMOS technology of standard to realize clock oscillator on sheet to replace the crystal oscillator outside sheet, for the cost reducing system, the integrated level improving system has great help.Realizing the main facing challenges of on chip clock oscillator is the stability how ensureing clock frequency, make frequency of oscillation not with temperature and supply voltage change and change.The frequency of oscillation of conventional ring oscillator is very large by the impact of mains voltage variations, and when supply voltage reduces by 50%, frequency reduces by more than 50%.
Figure 1 shows that the schematic diagram of traditional cmos annular oscillation circuit.As shown in Figure 1, traditional CMOS ring oscillator, wherein suppose that the pull-up PMOS in CMOS inverter is in saturation condition in the process of charging to electric capacity C always, pull-down NMOS pipe is also in saturation condition in discharge process always, and establish the rise time to equal fall time, according to analysis, frequency of oscillation is f=1/T, and cycle of oscillation is:
Visible, when threshold voltage one timing, with the reduction of supply voltage, charging and discharging currents reduces, and rising edge, trailing edge time increase, thus causes frequency of oscillation greatly to reduce.When ambient temperature changes, the parameter of transistor can change thereupon, thus causes the output frequency of oscillator to change, electron mobility μ n, hole mobility μ p, threshold voltage V
tHp, V
tHncapital changes with temperature, wherein:
μp∝T
-2.2
μn∝T
-2.2
V
THn＝V
THn0(1-kn T)
V
THp＝V
THp0(1-kp T)
In formula, kn and kp is greater than 0, V
tHp0and V
tHn0be respectively PMOS and the threshold voltage of NMOS tube when temperature 300K, can show that the output of oscillator also can raise along with the elevated frequencies of temperature.
Can show that the ring oscillator of this structure affects very large by temperature and power supply and process deviation etc., when temperature is-40 DEG C of+85 DEG C of range, operating voltage is when 3V-6V changes, the frequency fluctuation scope of oscillator is generally more than 30%, and its frequency accuracy cannot meet the requirement of a lot of application scenario.
In order to solve this technical problem, in prior art, propose some solutions.As document " a kind of improved CMOS ring oscillator of frequency stabilization " be loaded in " microelectronics " the 29th volume the 5th phase, document " a kind of improved CMOS ring oscillator of frequency stabilization " is loaded in " electromechanical engineering " the 28th volume the 2nd phase, and document " a kind of integrated CMOS ring oscillator of frequency stabilization " is loaded in " microelectronics " the 33rd volume the 3rd phase.As shown in Figure 2, the follow-on CMOS ring oscillator proposed in above-mentioned existing document mainly on discharge and recharge path by resistance current limliting, main delay is produced by resistive path, although frequency has and improves (when mains voltage variations 50% greatlyr, output frequency change 20%), but it have employed integrated resistor.This increases not only chip area, and the discreteness of integrated resistor resistance in manufacture technics very large (up to ± 20%), also can increase ring further and to shake the unsteadiness of output frequency.
In view of this, the purpose of this utility model is that providing a kind of can realize temperature-compensating with the ring oscillator circuit of stabilized frequency.
Utility model content
In order to overcome the defect existed in prior art, the utility model provides a kind of can realize temperature-compensating with the ring oscillator circuit of stabilized frequency.
In order to realize above-mentioned utility model object, the utility model discloses a kind of ring oscillator circuit, for realizing temperature-compensating with stabilizing clock frequency, it is characterized in that, comprise: a benchmark bandgap cell, for receiving a supply voltage and exporting the negative temperature coefficient voltage be inversely proportional to temperature and a bias voltage; One linear voltage stabilization unit, for receiving this negative temperature coefficient voltage and this bias voltage, exports the negative temperature coefficient voltage after an amplification; One ring oscillation unit, this ring oscillation unit receives the negative temperature coefficient voltage after this amplification as operating voltage, and this clock frequency of stable output; One level conversion unit, this level conversion unit receive this bias voltage for by the operating voltage of this ring oscillation unit by the negative temperature coefficient voltage transitions after this amplification for this supply voltage.
Further, this ring oscillator circuit comprises further: an alignment unit, and this alignment unit is connected with this ring oscillation unit with this linear voltage stabilization unit, for calibrating the negative temperature coefficient voltage after this amplification and this clock frequency.
Further, this benchmark bandgap cell comprises a band-gap reference circuit, for generation of an electric current proportional with absolute temperature; One reference voltage generating circuit, for generation of this negative temperature coefficient voltage; And a biasing circuit, for generation of this bias voltage.
Further, this band-gap reference circuit comprises first, second PMOS that is mirror, one operational amplifier, and one in first, second triode of mirror, comprises one first resistance between the positive pole of this operational amplifier and this first triode.
Further, this reference voltage generating circuit comprises one the 3rd PMOS, a temperature system trimming module, one second resistance and a third transistor.
Further, this biasing circuit comprises the 4th, the 5th PMOS in mirror,
And second, third NMOS tube in mirror.
Further, this benchmark bandgap cell comprises one first resistance and one second resistance, by regulating the resistance value ratio of this first, second resistance to obtain this negative temperature coefficient voltage.
Further, the error that this temperature system trimming module is used for process deviation produces trims.
Further, this linear voltage stabilization unit comprises a differential amplifier circuit, and the negative feedback voltage of this differential amplifier circuit equals this negative temperature coefficient voltage.
Further, this linear voltage stabilization unit also comprises a feedback network, and this feedback network can produce the negative temperature coefficient voltage after this amplification being proportional to this negative temperature coefficient voltage by regulating feedback factor.
Further, this feedback network comprises a calibration circuit, for calibrating the negative temperature coefficient voltage after this amplification.
Further, this ring oscillation unit also comprises a calibration circuit, for calibrating the frequency error because process deviation causes.
Further, this clock frequency as control signal, is controlled the charge or discharge of an inverter input by this level conversion unit, to realize the negative temperature coefficient voltage transitions after this amplification as this supply voltage.
Further, this charging current equals this discharging current.
Compared with prior art, the basis of ring oscillator circuit conventional ring oscillator provided by the utility model adds benchmark band-gap circuit, because the burning voltage produced is not with mains voltage variations, therefore the impact of supply voltage can be masked, Simultaneous Stabilization voltage can change with temperature, when the output frequency of annular oscillation circuit changes with temperature, burning voltage can change in the opposite direction, the impact of temperature can be balanced out, therefore can produce a stabilized frequency had nothing to do with temperature and supply voltage.
Accompanying drawing explanation
Can to be described in detail by following utility model and institute's accompanying drawings is further understood about advantage of the present utility model and spirit.
Fig. 1 is the schematic diagram of traditional cmos annular oscillation circuit;
Fig. 2 is the schematic diagram of the CMOS annular oscillation circuit used in prior art;
Fig. 3 is the structural representation of the high-precision annular oscillator involved by the utility model;
Fig. 4 is the detailed circuit diagram of the bandgap voltage reference unit of ring oscillator involved by the utility model;
Fig. 5 is the detailed circuit diagram of the linear voltage stabilization unit of ring oscillator involved by the utility model;
Fig. 6 is the detailed circuit diagram of the ring oscillation unit of ring oscillator involved by the utility model;
Fig. 7 is the detailed circuit diagram of the level oscillating unit of ring oscillator involved by the utility model.
Embodiment
Specific embodiment of the utility model is described in detail below in conjunction with accompanying drawing.
Fig. 3 is the structural representation of the high-precision annular oscillator involved by the utility model.As shown in Figure 3, ring oscillator circuit provided by the utility model, comprising: bandgap reference cell 101, linear voltage stabilization unit 102, ring oscillation unit 104, alignment unit 103 and level conversion unit 105.
Wherein, the operating voltage of bandgap voltage reference unit 101 is supply voltage VDD, and be subject to oscillator enable signal ENB and control, its output voltage Vref is not by power supply voltage variations affect and be inversely proportional to temperature, be supplied to linear voltage-stabilizing circuit as input reference level Vout, this bandgap voltage reference unit 101 is also for generation of the bias voltage of BIAS_P as the error amplifier of linear voltage-stabilizing circuit and the bias voltage of level conversion unit 105.
The operating voltage of linear voltage-stabilizing circuit 102 is still supply voltage VDD, and its bias voltage is the biased electrical bias voltage BIAS_P that prime bandgap voltage reference unit 101 produces, and is subject to oscillator enable signal ENB and controls; By comparing the Proportional Feedback of input reference level Vref and output level, under the negative feedback control of amplifier therein, produce constant output services voltage Vout, geometric ratio in the burning voltage of described bandgap voltage reference, and is trimmed voltage accurately by 3 refine calibration positions.
Ring oscillation unit 104, output frequency is proportional to the burning voltage of temperature and linear stable generation; Ring oscillation unit 104 also comprises the coarse adjustment calibration bits of frequency, can calibrate the frequency error having process deviation to cause.
Level conversion unit 105 passes through the clock signal of ring oscillation unit 104 generation as control signal, control the charge or discharge of the input of inverter, realize the conversion of level, simultaneously because charging current equals discharging current, therefore the clock output that duty ratio is 50% can be produced.
The supply voltage VDD of bandgap voltage reference unit 101, system enable signal ENB controls, produce not by power supply voltage variations affect with to the output voltage Vref that temperature is inversely proportional to, provide bias voltage BIAS_P to linear voltage stabilization unit 102 and bias voltage BIAS_P to level conversion unit 105 simultaneously.The benchmark input of linear voltage stabilization unit 102 is connected on the output of bandgap voltage reference unit 101, its operating voltage is also supply voltage VDD, the bias voltage BIAS_P that error amplifier is wherein exported by bandgap voltage reference unit 101 provides, and the negative feedback control of its error amplifying unit produces geometric ratio in the reference voltage V out of bandgap voltage reference Vref; Voltage control annular oscillating unit 104 works under reference voltage V out, and the amplitude of oscillation of stable output is the frequency of oscillation of Vout.One input of level conversion unit 105 is connected to the output of voltage-controlled oscillator 104, second input connects the output of the bias voltage BIAS_P of band gap reference voltage unit, its operating voltage is supply voltage VDD, makes the operating voltage of oscillator signal be transformed into supply voltage VDD from reference voltage V out.Charging and discharging currents due to level conversion unit 105 is equal can ensure that output duty cycle is the design objective frequency of 50%.
The utility model also adopts linear voltage-stabilizing circuit, stable operating voltage is provided to ring oscillator, adopt calibration circuit 103 to offset the frequency departure produced due to manufacturing condition change simultaneously, and by producing the Vout burning voltage of negative temperature coefficient, eliminate the frequency shift because temperature change causes.
Below concrete composition graphs 4-7 is described in detail the circuit implementations of this high-precision annular oscillator unit.
Fig. 4 is the detailed circuit diagram of the bandgap voltage reference unit of ring oscillator involved by the utility model.As shown in Figure 4, this bandgap voltage reference unit comprises start-up circuit, band-gap reference circuit, reference voltage generating circuit and biasing circuit.Start-up circuit is connected by PMOS P6, P7 series (P7_1 to P7_6 namely in Fig. 4), and NMOS tube N1, N5 form.Benchmark band-gap circuit is by PMOS P1, P2, and transport and placing device, resistance R1, triode Q1, Q2 composition is for generation of PTAT electric current.Reference voltage generating circuit is by PMOS P3, and resistance R2, triode Q3, temperature coefficient trimming module forms.Temperature coefficient trimming module comprises three digital calibration bits, according to the different digital signal of user's input, exports different temperature systems.Biasing circuit is made up of PMOS P4, P5 and NMOS tube N2, N3 to produce BIAS_P voltage.
Reference voltage generating circuit produces reference voltage V ref by PTAT current flowing resistance and PNP bipolar transistor, being reached by the resistance of regulating resistance R1, R2 makes reference voltage V ref not by the impact of supply voltage VDD and the object be inversely proportional to temperature, and position is trimmed to the temperature that resistance R2 is provided with 3, the error that process deviation produces is trimmed.The BIAS_P voltage that biasing circuit produces, still can produce the electric current be directly proportional to temperature and PTAT electric current.
Band-gap reference principle is as follows: because " empty short " characteristic (" empty short " characteristic refers to that amplifier two input terminal voltage is equal) of amplifier makes the voltage at INP and INN two ends equal, and P1, P2, P3 become mirror (i.e. electric current I 1=I2=I3):
That is: I
1* R
1+ V
bE1=V
bE2wherein V
bE=Vt*ln (I/I
ss), (wherein Vt=KT/q, K are Boltzmann constant, and T is thermodynamic temperature, and q is the quantity of electric charge, and I is the electric current flowing through transistor collector, I
sSfor triode saturation current)
Abbreviation formula obtains: I
1=(Vt*ln (n))/R1 wherein n is the number of parallel (in figure M=n) of q1 pipe.
Because Vt=KT/q is directly proportional to temperature (ln (n) is temperature independent, supposes that R1 and temperature also have nothing to do), so claim I
1and I
1image current be PTAT (PATA:proportional to absolute temperature and absolute temperature proportional) electric current.
Be aware of electric current I
1, can V be drawn
rEFterminal voltage, V
rEF=I
3* R
2+ V
bE3substitute into I
1(I
1=I
2=I
3):
V
REF＝V
BE3+(R
2*Vt*ln(n))/R
1，
Formula is had to find out U
bEbe inversely proportional to temperature, (R
2* Vt*ln (n))/R
1be directly proportional to temperature, can, by both adjustments proportionality coefficient, namely pass through to regulate R
2and R
1resistance change the temperature coefficient of Vref, become the voltage of the controlled negative temperature coefficient of slope.Its output voltage Vref is not by power supply voltage variations affect and be inversely proportional to temperature, be supplied to linear voltage-stabilizing circuit as input reference level, this band-gap reference voltage circuit also for generation of BIAS_P as the bias voltage of the error amplifier of linear voltage-stabilizing circuit and bias voltage BIAS_P to level shifting circuit.
Fig. 5 provides the conspectus of Fig. 3 neutral line voltage stabilizing circuit, and its operating voltage is still supply voltage VDD, and its bias voltage is the biased electrical bias voltage BIAS_P that prime band-gap reference voltage circuit produces, and is subject to oscillator enable signal ENB and controls; Wherein P302, P303, P304, N302, N303, N304 and R301, R302 resistance string forms operational amplifier, and the short characteristic of the void due to amplifier, makes amplifier two input terminal voltage equal, namely IN (the output Vref of connecting band gap reference circuit) is equal with FB (Vout produces through electric resistance partial pressure) terminal voltage, can draw Vout=(1+R301/R302) VFB and Vout=(1+R301/R302) Vref.By regulating the feedback proportional of R301 and R302 resistance, produce a voltage characteristic identical with Vref, amplitude is input voltage Vref (1+R301/R302) Vout doubly.And by 3 refine calibration positions, voltage is trimmed (by the ratio of numerical portion controlling resistance string R301 and R302, realizing the adjustment of Vout) accurately.
Fig. 6 gives the conspectus of Fig. 3 ring oscillator, comprise between 8 capacitance selection switch S 400 ~ S407 is that binary mode is arranged, binary weighting coarse adjustment is carried out to operating current, the deviation of the operating frequency of the ring oscillator brought with the process deviation trimmed owing to giving birth to process.The operating voltage of this ring oscillator exports the operating voltage Vout provided for linear voltage-stabilizing circuit, and is subject to oscillator enable signal ENB and controls.
Fig. 7 gives the conspectus of level shifting circuit in Fig. 1, its operating voltage is that supply voltage VDD makes the signal level of frequency of oscillation be transformed into operating voltage VDD from reference voltage V out, charging and discharging currents is all provided by bias voltage BIAS_P simultaneously, and in mirror, can ensure that output duty cycle is the design objective frequency of 50%.
Just preferred embodiment of the present utility model described in this specification, above embodiment is only in order to illustrate the technical solution of the utility model but not to restriction of the present utility model.All those skilled in the art comply with design of the present utility model by the available technical scheme of logical analysis, reasoning, or a limited experiment, all should within scope of the present utility model.
Claims (14)
1. a ring oscillator circuit, for realizing temperature-compensating with stabilizing clock frequency, is characterized in that, comprise:
One benchmark bandgap cell, for receiving a supply voltage and exporting the negative temperature coefficient voltage be inversely proportional to temperature and a bias voltage;
One linear voltage stabilization unit, for receiving described negative temperature coefficient voltage and described bias voltage, exports the negative temperature coefficient voltage after an amplification;
One ring oscillation unit, described ring oscillation unit receives the negative temperature coefficient voltage after described amplification as operating voltage, and the described clock frequency of stable output;
One level conversion unit, described level conversion unit receives described bias voltage for being described supply voltage by the operating voltage of described ring oscillation unit by the negative temperature coefficient voltage transitions after described amplification.
2. ring oscillator circuit as claimed in claim 1, it is characterized in that, described ring oscillator circuit comprises further: an alignment unit, described alignment unit is connected with described ring oscillation unit with described linear voltage stabilization unit, for calibrating the negative temperature coefficient voltage after described amplification and described clock frequency.
3. ring oscillator circuit as claimed in claim 1, it is characterized in that, described benchmark bandgap cell comprises a band-gap reference circuit, for generation of an electric current proportional with absolute temperature; One reference voltage generating circuit, for generation of described negative temperature coefficient voltage; And a biasing circuit, for generation of described bias voltage.
4. ring oscillator circuit as claimed in claim 3, it is characterized in that, described band-gap reference circuit comprises first, second PMOS that is mirror, one operational amplifier, and one in first, second triode of mirror, between the positive pole of described operational amplifier and described first triode, comprise one first resistance.
5. ring oscillator circuit as claimed in claim 3, it is characterized in that, described reference voltage generating circuit comprises one the 3rd PMOS, a temperature system trimming module, one second resistance and a third transistor.
6. ring oscillator circuit as claimed in claim 3, it is characterized in that, described biasing circuit comprises the 4th, the 5th PMOS in mirror, and second, third NMOS tube in mirror.
7. ring oscillator circuit as claimed in claim 1, it is characterized in that, described benchmark bandgap cell comprises one first resistance and one second resistance, by regulating the resistance value ratio of first, second resistance described to obtain described negative temperature coefficient voltage.
8. ring oscillator circuit as claimed in claim 5, is characterized in that, the error that described temperature system trimming module is used for process deviation produces trims.
9. ring oscillator circuit as claimed in claim 1, it is characterized in that, described linear voltage stabilization unit comprises a differential amplifier circuit, and the negative feedback voltage of described differential amplifier circuit equals described negative temperature coefficient voltage.
10. ring oscillator circuit as claimed in claim 9, it is characterized in that, described linear voltage stabilization unit also comprises a feedback network, and described feedback network can produce the negative temperature coefficient voltage after the described amplification being proportional to described negative temperature coefficient voltage by regulating feedback factor.
11. ring oscillator circuits as claimed in claim 10, it is characterized in that, described feedback network comprises a calibration circuit, for calibrating the negative temperature coefficient voltage after described amplification.
12. ring oscillator circuits as claimed in claim 1, it is characterized in that, described ring oscillation unit also comprises a calibration circuit, for calibrating the frequency error because process deviation causes.
13. ring oscillator circuits as claimed in claim 1, it is characterized in that, described clock frequency as control signal, is controlled the charge or discharge of an inverter input by described level conversion unit, is described supply voltage to realize the negative temperature coefficient voltage transitions after by described amplification.
14. ring oscillator circuits as claimed in claim 13, it is characterized in that, the charging current of described inverter input equals the discharging current of described inverter input.
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| CN201520286559.5U CN204633751U (en) | 2015-05-06 | 2015-05-06 | A kind of ring oscillator circuit |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105227180A (en) * | 2015-05-06 | 2016-01-06 | 上海晟矽微电子股份有限公司 | A kind of ring oscillator circuit |
| CN106788258A (en) * | 2015-12-22 | 2017-05-31 | 中国电子科技集团公司第二十研究所 | A kind of clock circuit of frequency stabilization |
| CN106961277A (en) * | 2017-04-18 | 2017-07-18 | 江苏信息职业技术学院 | A kind of VCO circuits of low-power high-performance |
| CN108365844A (en) * | 2018-05-10 | 2018-08-03 | 厦门华厦学院 | One kind can single chip integrated negative temperature coefficient compensated oscillator circuit |
-
2015
- 2015-05-06 CN CN201520286559.5U patent/CN204633751U/en active Active
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105227180A (en) * | 2015-05-06 | 2016-01-06 | 上海晟矽微电子股份有限公司 | A kind of ring oscillator circuit |
| CN106788258A (en) * | 2015-12-22 | 2017-05-31 | 中国电子科技集团公司第二十研究所 | A kind of clock circuit of frequency stabilization |
| CN106961277A (en) * | 2017-04-18 | 2017-07-18 | 江苏信息职业技术学院 | A kind of VCO circuits of low-power high-performance |
| CN106961277B (en) * | 2017-04-18 | 2023-04-28 | 江苏信息职业技术学院 | VCO circuit with low power and high performance |
| CN108365844A (en) * | 2018-05-10 | 2018-08-03 | 厦门华厦学院 | One kind can single chip integrated negative temperature coefficient compensated oscillator circuit |
| CN108365844B (en) * | 2018-05-10 | 2023-08-01 | 厦门华厦学院 | Monolithically-integrated negative temperature coefficient compensation oscillator circuit |
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