CN101425795B - Accurate saw-tooth wave generating circuit - Google Patents
Accurate saw-tooth wave generating circuit Download PDFInfo
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- CN101425795B CN101425795B CN2008101476096A CN200810147609A CN101425795B CN 101425795 B CN101425795 B CN 101425795B CN 2008101476096 A CN2008101476096 A CN 2008101476096A CN 200810147609 A CN200810147609 A CN 200810147609A CN 101425795 B CN101425795 B CN 101425795B
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Abstract
The invention discloses an accurate saw-tooth wave generating circuit which is characterized by comprising a lock phase ring and a dutyfactor adjusting ring, wherein the lock phase ring and the dutyfactor adjusting ring are connected in parallel to form a loop, the lock phase ring comprises two input parts and two output parts. The period, the phase position and the dutyfactor of a saw-tooth wave strictly follow an input reference clock in normal work, are irrelative to a technical angle or the temperature, and are determined by the negative feedback lock phase mechanism of the lock phase ring. The negative feedback mechanism of a dutyfactor adjusting circuit can improve the universal performance of the invention to prevent the dutyfactor of the input reference clock from being limited at a fixed value.
Description
Technical field
The present invention relates to integrated circuit fields, particularly a kind of accurate saw-tooth wave generating circuit.
Background technology
Sawtooth waveforms can be used as the phase interpolator input, produces with the clock of linear phase shift frequently through phase interpolator to be used for fields (as shown in Figure 3) such as data recovery.
Adopt sine wave to import in theory as phase interpolator, but because the intrinsic factor of circuit, be difficult to obtain accurate sine wave, in fact can use sawtooth waveforms to go the simulate ideal sine wave to import to obtain the better linearity degree as phase interpolator, the conventional tooth ripple is produced by open loop, its cycle and duty ratio (sawtooth waveforms rising fall time) have certain drift, have increased the non-linear of interpolation device output.
Summary of the invention
The purpose of this invention is to provide a kind of accurate saw-tooth wave generating circuit, can produce the constant accurate saw-tooth wave of cycle and duty ratio.
Technical scheme of the present invention is as follows:
A kind of accurate saw-tooth wave generating circuit is characterized in that: comprise phase-locked loop and duty cycle adjustment ring, described phase-locked loop comprises 2 inputs and 2 outputs with duty cycle adjustment ring formation in parallel loop, described phase-locked loop.
The concrete connected mode of described phase-locked loop and duty cycle adjustment ring is:
Duty ratio is the reference square wave clock input phase-locked loop of D, and phase-locked loop is output as and the sawtooth waveforms of reference clock with frequency, and phase-locked loop circuit constitutes the signal main channel.Another exports the input of duty cycle adjustment ring to phase-locked loop, and the output of duty cycle adjustment ring then feeds back to another input of phase-locked loop, forms feedback loop and carries out duty cycle adjustment.
Described duty ratio D 〉=50%; For the situation of D＜50%, this waveform is got final product by the standard CMOS inverter.
Described phase-locked loop comprises that phase discriminator, charge pump, voltage change lower threshold value decision circuit on current circuit, capacitor charge and discharge network and the sawtooth waveforms.
The course of work of described phase-locked loop is: two input signals of input reference clock and feedback clock are to phase discriminator, phase discriminator exports the charge pump input to, charge pump exports voltage to changes the current circuit input, voltage changes the current circuit output current IO, IO passing ratio coefficient is the current mirror circuit of K, the charging current value that obtains equals the value of I0, discharge current value equals K times of IO value (0＜K＜1), charge/discharge stream carries out charge/discharge to the capacitor charge and discharge network, capacitor charge and discharge network output sawtooth waveforms lower threshold value decision circuit to the sawtooth waveforms, lower threshold value decision circuit output switch control signal goes control capacitance to discharge and recharge network on the described sawtooth waveforms, simultaneously the lower threshold value decision circuit also will be exported feedback clock to phase discriminator and import on the sawtooth waveforms, finish phase-locked feedback loop.
Described duty cycle adjustment ring comprises duty cycle adjustment control circuit and duty ratio trim currents sources.
Lower threshold value decision circuit output feedback square wave clock to duty cycle adjustment control circuit is imported on the sawtooth waveforms, the duty cycle adjustment control circuit exports the input of duty ratio trim currents sources to, the duty cycle adjustment feedback loop is finished in the capacitor charge and discharge network input to the phase-locked loop module of duty ratio trim currents sources output fine setting discharging current.
By phase-locked and duty cycle adjustment is machine-processed, make the capacitor charge and discharge network charge and discharge produce on the electric capacity Cp with reference clock with the sawtooth waveforms of cycle with duty ratio, concrete workflow is as follows:
A, phase-locked loop are locked in reference clock by phase-locked mechanism with feedback clock;
If initial condition feedback clock relative reference clock has the phase difference ΔΦ, phase discriminator identifies ΔΦ and sends into charge pump, charge pump is converted into corresponding voltage with ΔΦ, change the charge/discharge current IO that current circuit is converted into described voltage on electric capacity charge/discharge network by voltage again, IO is proportional to electric capacity charge/discharge network and produces the sawtooth wave frequency, the lower threshold value decision circuit is converted into sawtooth waveforms with square wave frequently on the sawtooth waveforms, described square wave is feedback clock, and negative feedback mechanism makes IO move towards the direction that reduces the phase difference ΔΦ;
In the time of B, pll lock phase place, the duty cycle adjustment circuit makes the feedback clock duty ratio equate to be about D with the reference clock duty ratio.
The passing ratio coefficient is the current mirror circuit of K, obtain charging current=IO, discharging current=K * IO (0＜K＜1), make charging current/discharging current=K, difference small between charging current and the discharging current is just finely tuned by the duty ratio fine setting discharging current that the duty cycle adjustment circuit produces.This can revise owing to use fixedly charge/discharge stream, and because of the error of process deviation introducing; Can also increase simultaneously the versatility of this invention, make the input clock duty ratio no longer be confined to a certain particular value.K is determined by the reference clock duty ratio, K=(1-D)/D * ξ (D 〉=50%, ξ is the fine setting weight coefficient, get ξ=0.9 in this invention, represent the required charge/discharge current ratio of corresponding a certain particular duty cycle, 90% by the current mirror circuit realization, the 10% duty ratio fine setting discharging current realization by the generation of duty cycle adjustment circuit.For example during D=75%, K=0.3)
Sum up the overall work process: the about D reference clock of duty ratio--〉together frequently with identical duty ratio sawtooth waveforms.
Beneficial effect of the present invention is as follows:
1, input reference clock is followed in sawtooth wave period, phase place, duty ratio strictness during the phase-locked mechanism decision operate as normal of the negative feedback of phase-locked loop, and all irrelevant with process corner and temperature;
2, the negative feedback mechanism of duty cycle adjustment circuit can be revised because the error of using fixedly charge/discharge stream to introduce because of process deviation;
3, the negative feedback mechanism of duty cycle adjustment circuit can increase the versatility of this invention, makes the input reference clock duty ratio no longer be confined to a certain particular value.
Description of drawings
Fig. 1 is a structure principle chart of the present invention
Fig. 2 is an electrical block diagram of the present invention
Fig. 3 is the schematic diagram of application structure of the present invention
Fig. 4 is the schematic diagram of application structure of the present invention
Embodiment
Embodiment 1
As Figure 1-3, a kind of accurate saw-tooth wave generating circuit comprises phase-locked loop and duty cycle adjustment ring, and described phase-locked loop comprises 2 inputs and 2 outputs with duty cycle adjustment ring formation in parallel loop, described phase-locked loop.
The concrete connected mode of described phase-locked loop and duty cycle adjustment ring is:
Duty ratio is the reference square wave clock input phase-locked loop of D, and phase-locked loop is output as and the sawtooth waveforms of reference clock with frequency, and phase-locked loop circuit constitutes the signal main channel.Another exports the input of duty cycle adjustment ring to phase-locked loop, and the output of duty cycle adjustment ring then feeds back to another input of phase-locked loop, forms feedback loop and carries out duty cycle adjustment.
Described duty ratio D 〉=50%; For the situation of D＜50%, this waveform is got final product by the standard CMOS inverter.
Described phase-locked loop comprises that phase discriminator, charge pump, voltage change lower threshold value decision circuit on current circuit, capacitor charge and discharge network and the sawtooth waveforms.
The course of work of described phase-locked loop is: two input signals of input reference clock and feedback clock are to phase discriminator, phase discriminator exports the charge pump input to, charge pump exports voltage to changes the current circuit input, voltage changes the current circuit output current IO, IO passing ratio coefficient is the current mirror circuit of K, the charging current value that obtains equals the value of IO, discharge current value equals K times of IO value (0＜K＜1), charge/discharge stream carries out charge/discharge to the capacitor charge and discharge network, capacitor charge and discharge network output sawtooth waveforms lower threshold value decision circuit to the sawtooth waveforms, lower threshold value decision circuit output switch control signal goes control capacitance to discharge and recharge network on the described sawtooth waveforms, simultaneously the lower threshold value decision circuit also will be exported feedback clock to phase discriminator and import on the sawtooth waveforms, finish phase-locked feedback loop.
Described duty cycle adjustment ring comprises duty cycle adjustment control circuit and duty ratio trim currents sources.
Lower threshold value decision circuit output feedback square wave clock to duty cycle adjustment control circuit is imported on the sawtooth waveforms, the duty cycle adjustment control circuit exports the input of duty ratio trim currents sources to, the duty cycle adjustment feedback loop is finished in the capacitor charge and discharge network input to the phase-locked loop module of duty ratio trim currents sources output fine setting discharging current.
By phase-locked and duty cycle adjustment is machine-processed, make the capacitor charge and discharge network charge and discharge produce on the electric capacity Cp with reference clock with the sawtooth waveforms of cycle with duty ratio, concrete workflow is as follows:
A, phase-locked loop are locked in reference clock by phase-locked mechanism with feedback clock;
If initial condition feedback clock relative reference clock has the phase difference ΔΦ, phase discriminator identifies ΔΦ and sends into charge pump, charge pump is converted into corresponding voltage with ΔΦ, change the charge/discharge current IO that current circuit is converted into described voltage on electric capacity charge/discharge network by voltage again, IO is proportional to electric capacity charge/discharge network and produces the sawtooth wave frequency, the lower threshold value decision circuit is converted into sawtooth waveforms with square wave frequently on the sawtooth waveforms, described square wave is feedback clock, and negative feedback mechanism makes IO move towards the direction that reduces the phase difference ΔΦ;
In the time of B, pll lock phase place, the duty cycle adjustment circuit makes the feedback clock duty ratio equate to be about D with the reference clock duty ratio.
The passing ratio coefficient is the current mirror circuit of K, obtain charging current=IO, discharging current=K * IO (0＜K＜1), make charging current/discharging current=K, difference small between charging current and the discharging current is just finely tuned by the duty ratio fine setting discharging current that the duty cycle adjustment circuit produces.This can revise owing to use fixedly charge/discharge stream, and because of the error of process deviation introducing; Can also increase simultaneously the versatility of this invention, make the input clock duty ratio no longer be confined to a certain particular value.K is determined by the reference clock duty ratio, K=(1-D)/D * ξ (D 〉=50%, ξ is the fine setting weight coefficient, get ξ=0.9 in this invention, represent the required charge/discharge current ratio of corresponding a certain particular duty cycle, 90% by the current mirror circuit realization, the 10% duty ratio fine setting discharging current realization by the generation of duty cycle adjustment circuit.For example during D=75%, K=0.3)
Sum up the overall work process: the about D reference clock of duty ratio--〉together frequently with identical duty ratio sawtooth waveforms.
Embodiment 2
As shown in Figure 4, a kind of phase delay line structure, comprise phase-locked loop, duty cycle adjustment ring and equal component voltage-three modules of equipartition time change-over circuit, phase-locked loop and duty cycle adjustment ring form the loop, and the end output of phase-locked loop is connected with the input of equal component voltage-equipartition time change-over circuit.
The signal flow of described phase delay line structure is to being: duty ratio is about 50% reference square wave clock input phase-locked loop, one end of phase-locked loop is output as and the sawtooth waveforms of reference clock with frequency, phase-locked loop inputs to equal component voltage-equipartition time change-over circuit with sawtooth waveforms, all component voltage-equipartition time change-over circuit output and reference clock are with the n of frequency, the accurate five equilibrium of phase place square wave clock mutually, n 〉=2 wherein, phase-locked loop constitutes the signal main channel with equal component voltage-equipartition time change-over circuits; Simultaneously, another of phase-locked loop is output as and the square wave of reference clock with frequency, and phase-locked loop inputs to the duty cycle adjustment ring with square wave, duty cycle adjustment ring output duty cycle fine-adjusting current, described fine-adjusting current is regulated capacitor discharge electric current in the phase-locked loop, forms local feedback loop and carries out duty cycle adjustment.
Described phase-locked loop comprises that phase discriminator, charge pump, voltage change lower threshold value decision circuit on current circuit, capacitor charge and discharge network and the sawtooth waveforms.
In phase-locked loop, reference clock and feedback clock are as two input signal input phase discriminators, the input that exports charge pump to of phase discriminator, the input that exports voltage commentaries on classics current circuit to of charge pump, voltage changes the charge/discharge stream of the output current of current circuit as the capacitor charge and discharge network, capacitor charge and discharge network output sawtooth waveforms lower threshold value decision circuit to the sawtooth waveforms, lower threshold value decision circuit output switch control signal control capacitance discharges and recharges network on the sawtooth waveforms, the lower threshold value decision circuit also will be exported the input of feedback clock to phase discriminator on the sawtooth waveforms simultaneously, finish phase-locked feedback loop.
Described duty cycle adjustment ring comprises duty cycle adjustment control circuit and duty ratio trim currents sources.
In the duty cycle adjustment ring, lower threshold value decision circuit output feedback clock is to the input of duty cycle adjustment control circuit on the sawtooth waveforms of phase-locked loop, the duty cycle adjustment control circuit exports the input of duty ratio trim currents sources to, the duty cycle adjustment feedback loop is finished in the input of the capacitor charge and discharge network of duty ratio trim currents sources output fine setting discharging current to the phase-locked loop.
Described equal component voltage-equipartition time change-over circuit comprises resistance pressure-dividing network, comparator bank and trigger group.
In equal component voltage-equipartition time change-over circuit, be series at high reference voltage and low reference voltage (so-called high-low pressure voltage herein by 2 above substitutional resistances, it is the height of relatively determining each other, only relevant with relative value, and absolute value is irrelevant) between constitute resistance pressure-dividing network, each resistance gating switch all in parallel, described gating switch is controlled each resistance and whether is connected into resistance pressure-dividing network, resistance pressure-dividing network output each etc. component voltage each comparator negative terminal to the comparator bank respectively, the sawtooth waveforms of phase-locked loop output each comparator anode to the comparator bank, each comparator in the comparator bank is exported sawtooth waveforms and the clock input of each five equilibrium voltage comparative result to the corresponding trigger of trigger group respectively, on the square wave 1 of lower threshold value decision circuit output exports in the trigger group respectively with square wave 2 on the sawtooth waveforms of phase-locked loop, the input of following two trigger clocks, each DFF of trigger group (d type flip flop) trigger D and～Q connect and compose frequency divider, and the trigger group of n trigger formation is exported the n phase clock of the reference clock five equilibrium of 2 doubling times.
Described phase delay line structure be by phase-locked mechanism make discharge and recharge in the sheet content network charge and discharge on the electric capacity produce with reference clock with the sawtooth waveforms of cycle with duty ratio, each Along ent of this sawtooth waveforms is compared, method by equal component voltage-equipartition time converts the n phase square wave clock that spacing equates, wherein n 〉=2 to.
The concrete workflow of described phase delay line structure is as follows:
A, phase-locked loop are locked in reference clock by phase-locked mechanism with feedback clock;
If initial condition feedback clock relative reference clock has the phase difference ΔΦ, phase discriminator identifies ΔΦ and sends into charge pump, charge pump is converted into corresponding voltage with ΔΦ, change the charge/discharge current IO that current circuit is converted into described voltage on electric capacity charge/discharge network by voltage again, IO is proportional to electric capacity charge/discharge network and produces the sawtooth wave frequency, the lower threshold value decision circuit is converted into sawtooth waveforms with square wave frequently on the sawtooth waveforms, described square wave is feedback clock, and negative feedback mechanism makes IO move towards the direction that reduces the phase difference ΔΦ;
In the time of B, pll lock phase place, the duty cycle adjustment circuit makes the feedback clock duty ratio equate to be about 50% with the reference clock duty ratio, and promptly sawtooth waveforms equates rising/fall time;
In phase-locked loop capacitor charge and discharge network charging current is set and is slightly larger than discharging current, this small difference of charging current and discharging current is finely tuned by the duty ratio fine setting discharging current that the duty cycle adjustment circuit produces, and finally produces 50% constant duty ratio;
C, obtain frequency with identical with reference to square wave clock by steps A, B, the accurate saw-tooth wave that rise and fall time equates, use equal component voltage-equipartition time conversion then, by to sawtooth waveforms at the accurate five equilibrium of the ordinate (voltage) of single edge (rising/trailing edge), also just realized the accurate five equilibrium of its abscissa (time/phase place);
Resistance pressure-dividing network is the accurate five equilibrium of the amplitude of oscillation of sawtooth waveforms, produces branch reference point such as each amplitude of oscillation and sends into corresponding comparator negative terminal, the common comparator anode that connects of sawtooth waveforms input; In a certain rising edge process of sawtooth waveforms, each comparator is exported the digital level rising edge successively in the comparator bank, and this rising edge triggers the frequency divider that DFF constitutes, realized from etc. component voltage to the transformation of five equilibrium time (phase place).So far, finished function with any phase of the accurate five equilibrium of reference clock.
The course of work of described phase delay line structure is:
About 50% reference clock of duty ratio--〉is together frequently with identical duty ratio sawtooth waveforms--〉the five equilibrium sawtooth waveforms amplitude of oscillation--〉the five equilibrium sawtooth waveforms time (phase place).
Claims (5)
1. accurate saw-tooth wave generating circuit, it is characterized in that: comprise phase-locked loop and duty cycle adjustment ring, described phase-locked loop comprises 2 inputs and 2 outputs with duty cycle adjustment ring formation in parallel loop, described phase-locked loop; Described phase-locked loop comprises that phase discriminator, charge pump, voltage change lower threshold value decision circuit on current circuit, capacitor charge and discharge network and the sawtooth waveforms;
The course of work of described phase-locked loop is: two input signals of input reference clock and feedback clock are to phase discriminator, phase discriminator exports the charge pump input to, charge pump exports voltage to changes the current circuit input, voltage changes current circuit output current I0, I0 passing ratio coefficient is the current mirror circuit of K, the charging current value that obtains equals the value of I0, discharge current value equals K times of I0 value, 0＜K＜1, charge/discharge stream carries out charge/discharge to the capacitor charge and discharge network, capacitor charge and discharge network output sawtooth waveforms lower threshold value decision circuit to the sawtooth waveforms, lower threshold value decision circuit output switch control signal goes control capacitance to discharge and recharge network on the described sawtooth waveforms, simultaneously the lower threshold value decision circuit also will be exported feedback clock to phase discriminator and import on the sawtooth waveforms, finish phase-locked feedback loop;
Described duty cycle adjustment ring comprises duty cycle adjustment control circuit and duty ratio trim currents sources;
Lower threshold value decision circuit output feedback square wave clock to duty cycle adjustment control circuit is imported on the described sawtooth waveforms, the duty cycle adjustment control circuit exports the input of duty ratio trim currents sources to, the duty cycle adjustment feedback loop is finished in the capacitor charge and discharge network input to the phase-locked loop of duty ratio trim currents sources output fine setting discharging current.
2. according to the described a kind of accurate saw-tooth wave generating circuit of claim 1, it is characterized in that: the concrete connected mode of described phase-locked loop and duty cycle adjustment ring is: duty ratio is the reference clock input phase-locked loop of D, phase-locked loop is output as and the sawtooth waveforms of reference clock with frequency, phase-locked loop circuit constitutes the signal main channel, another exports the input of duty cycle adjustment ring to phase-locked loop, the output of duty cycle adjustment ring then feeds back to another input of phase-locked loop, forms feedback loop and carries out duty cycle adjustment.
3. according to the described a kind of accurate saw-tooth wave generating circuit of claim 2, it is characterized in that: described duty ratio D 〉=50%.
4. according to the described a kind of accurate saw-tooth wave generating circuit of claim 1, it is characterized in that:
By phase-locked loop and duty cycle adjustment ring mechanism, make the capacitor charge and discharge network charge and discharge on the electric capacity produce with reference clock with the sawtooth waveforms of cycle with duty ratio, concrete workflow is as follows:
A, phase-locked loop are locked in reference clock by phase-locked mechanism with feedback clock;
If initial condition feedback clock relative reference clock has the phase difference ΔΦ, phase discriminator identifies ΔΦ and sends into charge pump, charge pump is converted into corresponding voltage with ΔΦ, change the charging current I0 that current circuit is converted into described voltage on the capacitor charge and discharge network by voltage again, I0 is proportional to the capacitor charge and discharge network and produces the sawtooth wave frequency, the lower threshold value decision circuit is converted into sawtooth waveforms with square wave frequently on the sawtooth waveforms, described square wave is feedback clock, and negative feedback mechanism makes I0 move towards the direction that reduces the phase difference ΔΦ;
In the time of B, pll lock phase place, the duty cycle adjustment ring makes the feedback clock duty ratio equate to be D with the reference clock duty ratio.
5. according to the described a kind of accurate saw-tooth wave generating circuit of claim 1, it is characterized in that: the passing ratio coefficient is the current mirror circuit of K, obtain charging current=I0, discharging current=K * I0, make charging current/discharging current=K, difference small between charging current and the discharging current is just finely tuned by the fine setting discharging current of duty ratio trim currents sources output.
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| CN2008101476096A CN101425795B (en) | 2008-11-20 | 2008-11-20 | Accurate saw-tooth wave generating circuit |
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| CN2008101476096A CN101425795B (en) | 2008-11-20 | 2008-11-20 | Accurate saw-tooth wave generating circuit |
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| CN101425795B true CN101425795B (en) | 2010-12-08 |
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| CN103915358B (en) * | 2012-12-30 | 2017-02-08 | 比亚迪股份有限公司 | Process-corner automatic detection device and method |
| DE102014211110A1 (en) * | 2014-06-11 | 2015-12-17 | Robert Bosch Gmbh | Control circuit, voltage regulator and method for operating a voltage regulator |
| CN109115533B (en) * | 2018-09-07 | 2020-10-27 | 天津福云天翼科技有限公司 | Real-time accurate reproduction method of sine wave |
| CN111682863B (en) * | 2020-06-17 | 2023-08-22 | 灵矽微电子(深圳)有限责任公司 | Triangular wave generating circuit with stable output amplitude |
| CN113783552B (en) * | 2021-09-18 | 2023-02-07 | 温州大学 | Triangular wave signal generating system |
| CN113630108B (en) * | 2021-09-18 | 2023-02-07 | 温州大学 | Triangular wave signal parameter measurement circuit |
| CN115459747B (en) * | 2022-08-12 | 2023-09-01 | 北京伽略电子股份有限公司 | Sawtooth wave generating circuit with phase detection function and control method thereof |
| CN117748954B (en) * | 2024-02-19 | 2024-04-16 | 成都芯正微电子科技有限公司 | Triangular wave longitudinally adjustable Buck regulation and control circuit |
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