CN116131824A - Hysteresis comparator and hysteresis window adjusting method - Google Patents
Hysteresis comparator and hysteresis window adjusting method Download PDFInfo
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- CN116131824A CN116131824A CN202310109006.1A CN202310109006A CN116131824A CN 116131824 A CN116131824 A CN 116131824A CN 202310109006 A CN202310109006 A CN 202310109006A CN 116131824 A CN116131824 A CN 116131824A
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K5/00—Manipulating of pulses not covered by one of the other main groups of this subclass
- H03K5/22—Circuits having more than one input and one output for comparing pulses or pulse trains with each other according to input signal characteristics, e.g. slope, integral
- H03K5/24—Circuits having more than one input and one output for comparing pulses or pulse trains with each other according to input signal characteristics, e.g. slope, integral the characteristic being amplitude
- H03K5/2472—Circuits having more than one input and one output for comparing pulses or pulse trains with each other according to input signal characteristics, e.g. slope, integral the characteristic being amplitude using field effect transistors
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- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
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Abstract
The embodiment of the invention relates to the technical field of electronic circuits and discloses a hysteresis comparator with an adjustable hysteresis window and a hysteresis window adjusting method.
Description
Technical Field
The embodiment of the invention relates to the technical field of electronic circuits, in particular to a hysteresis comparator and a hysteresis window adjusting method.
Background
The hysteresis comparator is a comparator with hysteresis loop transmission characteristics, and a feedback loop is usually added between the positive input end of the comparator and the output end of the comparator, that is, the hysteresis comparator can be understood as a single-limit comparator with positive feedback, and has the advantage of high response speed. A further feature of the hysteresis comparator is that it has two threshold voltages, the values of which define the size of the hysteresis window of the hysteresis comparator.
In the process of implementing the embodiments of the present invention, the inventors found that at least the following problems exist in the above related art: at present, the size of a hysteresis window of the existing hysteresis comparator is related to the power supply voltage of the comparator, the resistance value of a resistor at the input end of the comparator and the positive feedback resistance value between the input end and the output end, and the parameters are usually determined after the model of the comparator and the resistor is selected when the hysteresis comparator is prepared, and the size of the hysteresis window is fixed and is not adjustable correspondingly.
Disclosure of Invention
The embodiment of the application provides a hysteresis comparator with an adjustable hysteresis window size and a hysteresis window adjusting method.
The aim of the embodiment of the invention is realized by the following technical scheme:
in order to solve the above technical problem, in a first aspect, an embodiment of the present invention provides a hysteresis comparator, including: a comparator including a positive input terminal and a negative input terminal, the comparator configured to output a high level when a voltage of the positive input terminal is higher than the negative input terminal, and to output a low level when the voltage of the negative input terminal is higher than the positive input terminal; the hysteresis window control unit comprises a pull-down current source, wherein the input end of the pull-down current source is respectively connected with the positive electrode input end and the negative electrode input end, the output end of the pull-down current source is grounded, and the hysteresis window control unit is configured to adjust the hysteresis window of the comparator by adjusting the current of the pull-down current source.
In some embodiments, the hysteresis comparator further comprises: the voltage detection unit comprises an in-phase signal output end and an anti-phase signal output end, wherein the in-phase signal output end is used for outputting a signal which is in phase with an output signal of the comparator, the anti-phase signal output end is used for outputting a signal which is opposite to the output signal of the comparator, the hysteresis window control unit further comprises a first control end and a second control end, the first control end is connected with the in-phase signal output end and used for controlling on-off between the pull-down current source and the negative electrode input end of the comparator, and the second control end is connected with the anti-phase signal output end and used for controlling on-off between the pull-down current source and the positive electrode input end of the comparator.
In some embodiments, the hysteresis window control unit further comprises: one end of the first switch is connected with the negative electrode input end of the comparator, the other end of the first switch is connected with the input end of the pull-down current source, the control end of the first switch is a first control end of the hysteresis window control unit and is connected with the in-phase signal output end of the voltage detection unit, and the first switch is configured to be closed when the in-phase signal output end outputs a high level; and one end of the second switch is connected with the positive electrode input end of the comparator, the other end of the second switch is connected with the input end of the pull-down current source, the control end of the second switch is the second control end of the hysteresis window control unit and is connected with the inverted signal output end of the voltage detection unit, and the second switch is configured to be closed when the inverted signal output end outputs high level.
In some embodiments, the hysteresis window control unit further comprises: a first input resistor, a first end of which is connected with the first end of the first switch and the negative electrode input end of the comparator; and the first end of the second input resistor is connected with the first end of the second switch and the positive electrode input end of the comparator.
In some embodiments, the hysteresis window of the hysteresis comparator is expressed as follows:
VFB(t1)-VFB(t2)＝ID*(R1+R2)
wherein VFB (t 1) -VFB (t 2) represent hysteresis windows of the hysteresis comparator, ID represents a current value of a current flowing through the pull-down current source, R1 represents a resistance value of the first input resistor, and R2 represents a resistance value of the second input resistor.
In some embodiments, the hysteresis window control unit further comprises: the gate of the first switch tube is a first input end of the hysteresis comparator, the source of the first switch tube is connected with the second end of the first input resistor, and the drain of the first switch tube is connected with a power supply; and the gate of the second switch tube is a second input end of the hysteresis comparator, the source of the second switch tube is connected with the second end of the second input resistor, and the drain of the second switch tube is connected with the drain of the first switch tube and the power supply.
In some embodiments, the hysteresis window control unit further comprises: the input end of the first bias current is respectively connected with the first end of the first input resistor, the first end of the first switch and the negative electrode input end of the comparator, and the output end of the first bias current is connected with the output end of the pull-down current source and grounded; and the input end of the second bias current is respectively connected with the first end of the second input resistor, the first end of the second switch and the positive electrode input end of the comparator, and the output end of the second bias current is connected with the output end of the pull-down current source and grounded.
In some embodiments, the voltage at the first input of the hysteresis comparator satisfies the following relationship when an inversion occurs:
VFB(t1)＝VREF+IB1*(R1-R2)+ID*R1
VFB(t2)＝VREF+IB2*(R1-R2)-ID*R2
wherein VFB (t 1) represents a voltage value of a first input terminal of the hysteresis comparator when the output signal of the hysteresis comparator is inverted from a high level to a low level, VFB (t 2) represents a voltage value of a first input terminal of the hysteresis comparator when the output signal of the hysteresis comparator is inverted from a low level to a high level, VREF represents a voltage value of a second input terminal of the hysteresis comparator, IB1 represents a current value of a current flowing through the first bias current, IB2 represents a current value of a current flowing through the second bias current, ID represents a current value of a current flowing through the pull-down current source, R1 represents a resistance value of the first input resistor, and R2 represents a resistance value of the second input resistor.
In some embodiments, the voltage detection unit includes: the input end of the buffer amplifier is connected with the output end of the comparator, the output end of the buffer amplifier is an in-phase signal output end of the voltage detection unit, and the buffer amplifier is configured such that an output signal output by the output end of the buffer amplifier is in-phase with an input signal input by the input end of the buffer amplifier; and the input end of the inverter is connected with the output end of the buffer amplifier, the output end of the inverter is an inverted signal output end of the voltage detection unit, and the inverter is configured to enable an output signal output by the output end of the inverter to be inverted with an input signal input by the input end of the inverter.
In order to solve the above technical problem, in a second aspect, an embodiment of the present invention provides a hysteresis window adjusting method, which is applied to the hysteresis comparator according to the first aspect, and the method includes: and adjusting the current of a pull-down current source in a hysteresis window control unit of the hysteresis comparator to adjust a hysteresis window of the comparator, wherein when the current value of the pull-down current source is increased, the hysteresis comparator increases a voltage threshold value which is outputted from high level inversion to low level, decreases the voltage threshold value which is outputted from low level inversion to high level, and when the current value of the pull-down current source is decreased, the hysteresis comparator decreases the voltage threshold value which is outputted from high level inversion to low level, and increases the voltage threshold value which is outputted from low level inversion to high level.
Compared with the prior art, the invention has the beneficial effects that: compared with the prior art, the embodiment of the invention provides a hysteresis comparator with an adjustable hysteresis window and a hysteresis window adjusting method, wherein the hysteresis comparator at least comprises a comparator and a hysteresis window control unit, and can also comprise a voltage detection unit for detecting an output signal of the comparator, the comparator comprises a positive electrode input end and a negative electrode input end, the hysteresis window control unit comprises a pull-down current source, the input ends of the pull-down current source are respectively connected with the positive electrode input end and the negative electrode input end, and the hysteresis window control unit can adjust the hysteresis window of the comparator by adjusting the current of the pull-down current source.
Drawings
One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements/modules and steps, and in which the figures do not include the true to scale unless expressly indicated by the contrary reference numerals.
FIG. 1 is a block diagram of a hysteresis comparator according to an embodiment of the present invention;
fig. 2 is a schematic circuit diagram of a hysteresis comparator according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a hysteresis comparator according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a hysteresis window of the hysteresis comparator shown in FIGS. 1-3;
fig. 5 is a flowchart of a hysteresis window adjusting method according to a second embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.
It should be noted that, if not conflicting, the various features of the embodiments of the present invention may be combined with each other, which are all within the protection scope of the present application. In addition, while functional block division is performed in a device diagram and logical order is shown in a flowchart, in some cases, the steps shown or described may be performed differently than block division in a device, or order in a flowchart. Moreover, the words "first," "second," and the like as used herein do not limit the data and order of execution, but merely distinguish between identical or similar items that have substantially the same function and effect. It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or one or more intervening elements may be present therebetween.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
In order to solve the problems that the size of a hysteresis window of a hysteresis comparator is fixed and cannot be adjusted in the existing hysteresis window comparator, the embodiment of the invention provides a hysteresis comparator with an adjustable hysteresis window and a hysteresis window adjusting method thereof.
In particular, embodiments of the present invention are further described below with reference to the accompanying drawings.
Example 1
Referring to fig. 1, a block diagram of a hysteresis comparator provided in an embodiment of the present invention is shown, where the hysteresis comparator 10 at least includes: a comparator U1 and a hysteresis window control unit 11. In some embodiments, the hysteresis comparator 10 may further include a voltage detection unit 12, fig. 1 illustrates a case where the hysteresis comparator 10 includes and separately sets the voltage detection unit 12, the comparator U1, and the hysteresis window control unit 11, and in practical applications, the voltage detection unit 12 may also be integrated in the hysteresis window control unit 11, which is not limited to the example shown in fig. 1.
The comparator U1 includes a positive input terminal and a negative input terminal, and the comparator 11 is configured to output a high level when the voltage VP of the positive input terminal is higher than the voltage VN of the negative input terminal, and to output a low level when the voltage VN of the negative input terminal is higher than the voltage VP of the positive input terminal. Specifically, the first input end of the hysteresis comparator 10 is used for inputting an input voltage VFB to be modulated, the input voltage VFB is modulated into a voltage VN and then enters the comparator U1 through the positive input end, the second input end of the hysteresis comparator 10 is used for inputting a reference voltage VREF, the reference voltage VREF is modulated into a voltage VP and then enters the comparator U1 through the negative input end, and the voltage VN is compared with the voltage VP in the comparator U1. When the voltage VP is higher than the voltage VN, that is, the input voltage VFB is higher than the reference voltage VREF, the comparator U1 outputs a high level, that is, comp_out is output as 1, and when the input voltage VFB gradually increases and reaches the voltage threshold VFB (t 1), the comparator U1 inverts to output a low level, that is, comp_out inverts to output as 0; when the voltage VP is lower than the voltage VN, i.e. the input voltage VFB is lower than the reference voltage VREF, the comparator U1 outputs a low level, i.e. comp_out is output as 0, and when the input voltage VFB gradually decreases and reaches the voltage threshold VFB (t 2), the comparator U1 inverts to output a high level, i.e. comp_out inverts to output as 1.
The voltage detection unit 12 includes an in-phase signal output terminal for outputting a signal s1 in phase with the output signal of the comparator and an anti-phase signal output terminal for outputting a signal s2 in phase with the output signal of the comparator. Specifically, referring to fig. 2, which shows a circuit structure of a hysteresis comparator according to an embodiment of the present invention, the voltage detection unit 12 includes: a buffer amplifier U2 and an inverter U3. The input end of the buffer amplifier U2 is connected with the output end of the comparator U1, the output end of the buffer amplifier U2 is an in-phase signal output end of the voltage detection unit 12, and the buffer amplifier U2 is configured such that an output signal s1 output by the output end of the buffer amplifier U2 is in-phase with an input signal input by the input end of the buffer amplifier U2; the input end of the inverter U3 is connected to the output end of the buffer amplifier U2, the output end of the inverter U3 is an inverted signal output end of the voltage detection unit 12, and the inverter is configured such that an output signal s2 output by the output end of the inverter is inverted to an input signal s1 input by the input end of the inverter.
The hysteresis window control unit 11 includes a pull-down current source ID, an input end of the pull-down current source ID is connected to the positive input end and the negative input end, an output end of the pull-down current source ID is grounded, and the hysteresis window control unit 11 is configured to adjust a hysteresis window of the comparator U1 by adjusting a current magnitude of the pull-down current source ID.
The hysteresis window control unit 11 further comprises a first control end and a second control end, wherein the first control end is connected with the in-phase signal output end and used for controlling the on-off between the pull-down current source ID and the negative input end of the comparator U1, and the second control end is connected with the reverse signal output end and used for controlling the on-off between the pull-down current source ID and the positive input end of the comparator U1.
Specifically, please continue to refer to fig. 2, the hysteresis window control unit 11 further includes: a first switch sw1 and a second switch sw2. One end of the first switch sw1 is connected to the negative input end of the comparator U1, the other end of the first switch sw1 is connected to the input end of the pull-down current source ID, the control end of the first switch sw1 is a first control end of the hysteresis window control unit 11 and is connected to the in-phase signal output end of the voltage detection unit 12, and the first switch sw1 is configured to be closed when the in-phase signal output end outputs a high level; and one end of the second switch sw2 is connected with the positive electrode input end of the comparator U1, the other end of the second switch sw2 is connected with the input end of the pull-down current source ID, the control end of the second switch sw2 is the second control end of the hysteresis window control unit 11 and is connected with the inverted signal output end of the voltage detection unit 12, and the second switch sw2 is configured to be closed when the inverted signal output end outputs a high level. The first switch sw1 and the second switch sw2 may be switching devices such as an electronic switch and a relay, and can be used for controlling whether to be closed according to the received level signal, and specifically, the switch types of the first switch sw1 and the second switch sw2 may be selected according to actual needs.
With continued reference to fig. 2, the hysteresis window control unit 11 further includes: a first input resistor R1 and a second input resistor R2. The first input resistor R1 has a first end connected to the first end of the first switch sw1 and the negative input end of the comparator U1, and a second end that is the first input end of the hysteresis comparator 10, where the hysteresis comparator 10 is configured to compare the voltage VFB input from the first input end with the reference voltage VREF, and further output a high level signal or a low level signal; the first end of the second input resistor R2 is connected to the first end of the second switch sw2 and the positive input end of the comparator U1, and the second end of the second input resistor R2 is the second input end of the hysteresis comparator 10, and is used for inputting the reference voltage VREF.
In some embodiments, please refer to fig. 3, which illustrates a circuit structure of another hysteresis comparator provided in an embodiment of the present invention, the hysteresis window control unit 11 may further include: a first switching tube m1 and a second switching tube m2. The gate of the first switch tube m1 is a first input end of the hysteresis comparator 10, the source of the first switch tube m1 is connected with the second end of the first input resistor sw1, and the drain of the first switch tube m1 is connected with the power supply VDD; the gate of the second switching tube is the second input end of the hysteresis comparator 10, the source of the second switching tube is connected with the second end of the second input resistor sw2, and the drain of the second switching tube is connected with the drain of the first switching tube m1 and the power supply VDD. In the example shown in fig. 3, the first switching tube m1 and the second switching tube m2 are NMOS (N-Metal-Oxide-Semiconductor) tubes, and the turn-on threshold is vtn, and in other embodiments, the types of the first switching tube m1 and the second switching tube m2 and the turn-on threshold vtn thereof may be set according to actual needs, which is not limited by the embodiments of the present invention.
With continued reference to fig. 3, the hysteresis window control unit 11 further includes: a first bias current IB1 and a second bias current IB2. The input end of the first bias current IB1 is connected to the first end of the first input resistor R1, the first end of the first switch sw1, and the negative input end of the comparator U1, and the output end of the first bias current IB1 is connected to the output end of the pull-down current source ID and grounded; the input end of the second bias current IB is respectively connected with the first end of the second input resistor R2, the first end of the second switch sw2 and the positive input end of the comparator U1, and the output end of the second bias current IB is connected with the output end of the pull-down current source ID and grounded.
It should be noted that, both the current flowing through the first bias current IB1 and the current flowing through the second bias current IB2 need to pass through the first switching transistor m1, the first input resistor R1, the second switching transistor m2, and the second input resistor R2, and therefore, the current value of the current flowing through the first bias current IB1 is equal to the current value of the current flowing through the second bias current IB2, that is, ib1=ib2.
Referring to fig. 4, which is a schematic diagram illustrating a hysteresis window of the hysteresis comparator 10 shown in fig. 1 to 3, when the hysteresis comparator 10 provided in the embodiment of the present invention works, for the two circuit structures of fig. 2 and 3, two cases are respectively divided:
under the circuit configuration shown in fig. 2, when the input voltage VFB is higher than the reference voltage VREF, the voltage VP is also higher than the voltage VN, the comparator U1 outputs a high level signal, i.e., comp_out=1, at this time, the buffer amplifier U2 also outputs a high level signal, i.e., s1=1, and the inverter U3 outputs a low level signal, i.e., s2=0, so as to control the first switch sw1 to be closed and turned on, and the second switch sw2 to be opened, at this time, the voltage vp=vref at the positive input terminal of the comparator U1, the voltage vn=vfb-ID at the reverse input terminal scans the input voltage VFB from low to high, and when the input voltage VFB gradually increases and reaches the voltage threshold VFB (t 1), the comparator U1 inverts to output a low level, i.e., comp_out=0.
Under the circuit configuration shown in fig. 2, when the input voltage VFB is lower than the reference voltage VREF, the voltage VP is also lower than the voltage VN, the comparator U1 outputs a low level signal, i.e., comp_out=0, at this time, the buffer amplifier U2 also outputs a low level signal, i.e., s1=0, the inverter U3 outputs a high level signal, i.e., s2=1, so as to control the first switch sw1 to be opened, the second switch sw2 to be closed and turned on, at this time, the voltage vp=vref-ID of the positive input terminal of the comparator U1 is equal to R2, the voltage vn=vfb of the negative input terminal is scanned from high to low, and when the input voltage VFB gradually decreases and reaches the voltage threshold VFB (t 2), the comparator U1 inverts to output a high level, i.e., comp_out=1.
In addition, in the circuit structure shown in fig. 2, the voltage at the first input terminal of the hysteresis comparator 10 satisfies the following relationship when the inversion occurs:
VFB(t1)＝VREF+ID*R1
VFB(t2)＝VREF-ID*R2
wherein VFB (t 1) represents a voltage value of a first input terminal of the hysteresis comparator when the output signal of the hysteresis comparator is inverted from a high level to a low level, VFB (t 2) represents a voltage value of a first input terminal of the hysteresis comparator when the output signal of the hysteresis comparator is inverted from a low level to a high level, VREF represents a voltage value of a second input terminal of the hysteresis comparator, ID represents a current value of a current flowing through the pull-down current source, R1 represents a resistance value of the first input resistor, and R2 represents a resistance value of the second input resistor.
In the circuit structure shown in fig. 3, when the input voltage VFB is higher than the reference voltage VREF, the voltage VP is also higher than the voltage VN, the comparator U1 outputs a high level signal, i.e. comp_out=1, at this time, the buffer amplifier U2 also outputs a high level signal, i.e. s1=1, the inverter U3 outputs a low level signal, i.e. s2=0, so as to control the first switch sw1 to be closed and turned on, and the second switch sw2 to be opened, at this time, the voltage vp=vref-vtn-IB 2R 2 at the positive input terminal of the comparator U1, the voltage vn=vfb-vtn-IB 1R 1-ID R1 at the negative input terminal scans the input voltage VFB from low to high, and when the input voltage VFB gradually increases and reaches the voltage threshold VFB (t 1), the comparator U1 inverts to output a low level, i.e. comp_out=0.
In the circuit structure shown in fig. 3, when the input voltage VFB is lower than the reference voltage VREF, the voltage VP is also lower than the voltage VN, the comparator U1 outputs a low level signal, i.e. comp_out=0, at this time, the buffer amplifier U2 also outputs a low level signal, i.e. s1=0, the inverter U3 outputs a high level signal, i.e. s2=1, so as to control the first switch sw1 to be opened, the second switch sw2 to be closed and turned on, at this time, the voltage vp=vref-vtn-ib2×r2-ID of the positive input terminal of the comparator U1 is equal to R2-ID of the positive input terminal, the voltage vn=vfb-vtn-ib1×r1 of the negative input terminal scans the input voltage VFB from high to low, and when the input voltage VFB gradually decreases and reaches the voltage threshold VFB (t 2), the comparator U1 inverts to output a high level, i.e. comp_out=1.
In addition, in the circuit structure shown in fig. 2, the voltage at the first input terminal of the hysteresis comparator 10 satisfies the following relationship when the inversion occurs:
VFB(t1)＝VREF+IB1*(R1-R2)+ID*R1
VFB(t2)＝VREF+IB2*(R1-R2)-ID*R2
wherein VFB (t 1) represents a voltage value of a first input terminal of the hysteresis comparator when the output signal of the hysteresis comparator is inverted from a high level to a low level, VFB (t 2) represents a voltage value of a first input terminal of the hysteresis comparator when the output signal of the hysteresis comparator is inverted from a low level to a high level, VREF represents a voltage value of a second input terminal of the hysteresis comparator, IB1 represents a current value of a current flowing through the first bias current, IB2 represents a current value of a current flowing through the second bias current, ID represents a current value of a current flowing through the pull-down current source, R1 represents a resistance value of the first input resistor, and R2 represents a resistance value of the second input resistor.
Furthermore, since ib1=ib2 in the embodiment of the present invention, both the two relations of the voltage at the first input terminal of the hysteresis comparator 10 when the inversion occurs can be obtained, both the circuit structures of fig. 2 and 3, the expression of the hysteresis window of the hysteresis comparator 10 is as follows:
VFB(t1)-VFB(t2)＝ID*(R1+R2)
wherein VFB (t 1) -VFB (t 2) represent hysteresis windows of the hysteresis comparator, ID represents a current value of a current flowing through the pull-down current source, R1 represents a resistance value of the first input resistor, and R2 represents a resistance value of the second input resistor.
In the embodiment of the invention, when the hysteresis comparator is prepared, the types of the comparator U1, the first input resistor R1 and the second input resistor R2 are selected, and after the resistance values of the first input resistor R1 and the second input resistor R2 are determined, referring to the expression of the hysteresis window, the size of the hysteresis window can be adjusted by adjusting the current value ID of the pull-down current source. The embodiment of the invention provides the hysteresis comparator with a simple structure and an adjustable hysteresis window, and the control method is very simple.
Example two
The embodiment of the invention provides a hysteresis window adjusting method, which is applied to a hysteresis comparator as described in the first embodiment, and the specific structure and the working principle of the hysteresis comparator are shown in the first embodiment and fig. 1 to fig. 4, and are not described in detail herein. Referring to fig. 5, a flow of a hysteresis window adjusting method according to an embodiment of the present invention is shown, where the method includes but is not limited to the following steps:
step S100: adjusting the current magnitude of a pull-down current source in a hysteresis window control unit of the hysteresis comparator to adjust a hysteresis window of the comparator,
specifically, referring to the first embodiment and fig. 1 to 4, and referring to the formulas of the voltage thresholds VFB (t 1) and VFB (t 2) of the first input terminal of the hysteresis comparator 10 when the inversion occurs, when the current value of the pull-down current source ID is increased, the voltage threshold VFB (t 1) of the hysteresis comparator U1 is increased by outputting the voltage threshold VFB (t 1) of the high level inversion output to the low level, and the voltage threshold VFB (t 2) of the low level inversion output to the high level is decreased; conversely, when the current value of the pull-down current source ID is reduced, the hysteresis comparator decreases the voltage threshold VFB (t 1) outputted to the low level by the output high level inversion, and increases the voltage threshold VFB (t 2) outputted to the high level by the output low level inversion.
The embodiment of the invention provides a hysteresis comparator with an adjustable hysteresis window and a hysteresis window adjusting method, wherein the hysteresis comparator at least comprises a comparator and a hysteresis window control unit, and can also comprise a voltage detection unit for detecting an output signal of the comparator, the comparator comprises a positive electrode input end and a negative electrode input end, the hysteresis window control unit comprises a pull-down current source, the input ends of the pull-down current source are respectively connected with the positive electrode input end and the negative electrode input end, and the hysteresis window control unit can adjust the hysteresis window of the comparator by adjusting the current of the pull-down current source.
It should be noted that the above-described apparatus embodiments are merely illustrative, and the units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
From the above description of embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus a general purpose hardware platform, or may be implemented by hardware. Those skilled in the art will appreciate that all or part of the processes implementing the methods of the above embodiments may be implemented by a computer program for instructing relevant hardware, where the program may be stored in a computer readable storage medium, and the program may include processes of the embodiments of the methods described above when executed. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), or the like.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; the technical features of the above embodiments or in the different embodiments may also be combined within the idea of the invention, the steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in details for the sake of brevity; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (10)
1. A hysteresis comparator, comprising:
a comparator including a positive input terminal and a negative input terminal, the comparator configured to output a high level when a voltage of the positive input terminal is higher than the negative input terminal, and to output a low level when the voltage of the negative input terminal is higher than the positive input terminal;
the hysteresis window control unit comprises a pull-down current source, wherein the input end of the pull-down current source is respectively connected with the positive electrode input end and the negative electrode input end, the output end of the pull-down current source is grounded, and the hysteresis window control unit is configured to adjust the hysteresis window of the comparator by adjusting the current of the pull-down current source.
2. The hysteresis comparator of claim 1, further comprising:
a voltage detection unit including an in-phase signal output terminal for outputting a signal in phase with an output signal of the comparator and an anti-phase signal output terminal for outputting a signal in phase with the output signal of the comparator,
the hysteresis window control unit further comprises a first control end and a second control end, wherein the first control end is connected with the in-phase signal output end and used for controlling the on-off between the pull-down current source and the negative electrode input end of the comparator, and the second control end is connected with the reverse phase signal output end and used for controlling the on-off between the pull-down current source and the positive electrode input end of the comparator.
3. The hysteresis comparator of claim 2, wherein the hysteresis window control unit further comprises:
one end of the first switch is connected with the negative electrode input end of the comparator, the other end of the first switch is connected with the input end of the pull-down current source, the control end of the first switch is a first control end of the hysteresis window control unit and is connected with the in-phase signal output end of the voltage detection unit, and the first switch is configured to be closed when the in-phase signal output end outputs a high level;
and one end of the second switch is connected with the positive electrode input end of the comparator, the other end of the second switch is connected with the input end of the pull-down current source, the control end of the second switch is the second control end of the hysteresis window control unit and is connected with the inverted signal output end of the voltage detection unit, and the second switch is configured to be closed when the inverted signal output end outputs high level.
4. A hysteresis comparator according to claim 3, wherein said hysteresis window control unit further comprises:
a first input resistor, a first end of which is connected with the first end of the first switch and the negative electrode input end of the comparator;
and the first end of the second input resistor is connected with the first end of the second switch and the positive electrode input end of the comparator.
5. The hysteresis comparator of claim 4, wherein,
the hysteresis window of the hysteresis comparator is expressed as follows:
VFB(t1)-VFB(t2)＝ID*(R1+R2)
wherein VFB (t 1) -VFB (t 2) represent hysteresis windows of the hysteresis comparator, ID represents a current value of a current flowing through the pull-down current source, R1 represents a resistance value of the first input resistor, and R2 represents a resistance value of the second input resistor.
6. The hysteresis comparator of claim 4, wherein the hysteresis window control unit further comprises:
the gate of the first switch tube is a first input end of the hysteresis comparator, the source of the first switch tube is connected with the second end of the first input resistor, and the drain of the first switch tube is connected with a power supply;
and the gate of the second switch tube is a second input end of the hysteresis comparator, the source of the second switch tube is connected with the second end of the second input resistor, and the drain of the second switch tube is connected with the drain of the first switch tube and the power supply.
7. The hysteresis comparator of claim 4, wherein the hysteresis window control unit further comprises:
the input end of the first bias current is respectively connected with the first end of the first input resistor, the first end of the first switch and the negative electrode input end of the comparator, and the output end of the first bias current is connected with the output end of the pull-down current source and grounded;
and the input end of the second bias current is respectively connected with the first end of the second input resistor, the first end of the second switch and the positive electrode input end of the comparator, and the output end of the second bias current is connected with the output end of the pull-down current source and grounded.
8. The hysteresis comparator of claim 7, wherein,
the voltage at the first input end of the hysteresis comparator satisfies the following relationship when inversion occurs:
VFB(t1)＝VREF+IB1*(R1-R2)+ID*R1
VFB(t2)＝VREF+IB2*(R1-R2)-ID*R2
wherein VFB (t 1) represents a voltage value of a first input terminal of the hysteresis comparator when the output signal of the hysteresis comparator is inverted from a high level to a low level, VFB (t 2) represents a voltage value of a first input terminal of the hysteresis comparator when the output signal of the hysteresis comparator is inverted from a low level to a high level, VREF represents a voltage value of a second input terminal of the hysteresis comparator, IB1 represents a current value of a current flowing through the first bias current, IB2 represents a current value of a current flowing through the second bias current, ID represents a current value of a current flowing through the pull-down current source, R1 represents a resistance value of the first input resistor, and R2 represents a resistance value of the second input resistor.
9. Hysteresis comparator according to any of claims 2-8, wherein the voltage detection unit comprises:
the input end of the buffer amplifier is connected with the output end of the comparator, the output end of the buffer amplifier is an in-phase signal output end of the voltage detection unit, and the buffer amplifier is configured such that an output signal output by the output end of the buffer amplifier is in-phase with an input signal input by the input end of the buffer amplifier;
and the input end of the inverter is connected with the output end of the buffer amplifier, the output end of the inverter is an inverted signal output end of the voltage detection unit, and the inverter is configured to enable an output signal output by the output end of the inverter to be inverted with an input signal input by the input end of the inverter.
10. A hysteresis window adjusting method applied to a hysteresis comparator according to any one of claims 1-9, said method comprising:
adjusting the current magnitude of a pull-down current source in a hysteresis window control unit of the hysteresis comparator to adjust a hysteresis window of the comparator, wherein,
when the current value of the pull-down current source is increased, the voltage threshold value of the hysteresis comparator, which is inverted from the output high level to the low level, is increased, the voltage threshold value of the pull-down current source, which is inverted from the output low level to the high level, is decreased,
when the current value of the pull-down current source is reduced, the voltage threshold of the hysteresis comparator, which is inverted from the output high level to the low level, is reduced, and the voltage threshold of the hysteresis comparator, which is inverted from the output low level to the high level, is increased.
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| CN202310109006.1A CN116131824A (en) | 2023-02-13 | 2023-02-13 | Hysteresis comparator and hysteresis window adjusting method |
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| CN202310109006.1A CN116131824A (en) | 2023-02-13 | 2023-02-13 | Hysteresis comparator and hysteresis window adjusting method |
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