CN1909369A - Voltage comparator having hysteresis characteristics - Google Patents
Voltage comparator having hysteresis characteristics Download PDFInfo
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- CN1909369A CN1909369A CN 200610086548 CN200610086548A CN1909369A CN 1909369 A CN1909369 A CN 1909369A CN 200610086548 CN200610086548 CN 200610086548 CN 200610086548 A CN200610086548 A CN 200610086548A CN 1909369 A CN1909369 A CN 1909369A
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- hysteresis characteristic
- voltage comparator
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Abstract
The present invention relates to a voltage comparator having hysteresis characteristics. The voltage comparator having hysteresis characteristics includes a comparing section that compares an input voltage with a reference voltage so as to output a high-level or low-level signal; and a reference voltage changing section that changes the reference voltage when a low-level signal is output from the comparing section.
Description
The cross reference of related application
The application requires the priority of the korean patent application submitted to Korea S Department of Intellectual Property on August 2nd, 2005 2005-0070553 number and the priority of the korean patent application submitted to Korea S Department of Intellectual Property on March 29th, 2006 2006-0028621 number, and the content of its disclosure is hereby expressly incorporated by reference.
Technical field
The present invention relates to have the voltage comparator of hysteresis characteristic, more specifically, relate to a kind of voltage comparator with hysteresis characteristic, wherein increase the reference voltage that constitutes by a few components and changed part, so that can design the voltage comparator of avoiding importing noise jamming, and the size of hysteresis voltage can accurately be set, and by changing the size that resistance value can change hysteresis voltage simply.
Background technology
In general, voltage comparator is compared input voltage with reference voltage, and amplifies the difference of the two, so that output high level or low level signal.Because traditional voltage comparator does not have the function to output compensation noise, independent analog or digital compensating circuit is arranged thereon so add.
The circuit in order to the solution noise problem as being additional to voltage comparator provides the Schmidt (Schmitt) with hysteresis characteristic circuits for triggering.Yet, Schmidt trigger circuit when definite positive threshold voltage vt h+ and negative threshold voltage Vth-to process variables (process variation) sensitivity.
Recently, voltage comparator itself is designed to have hysteresis characteristic.
With input voltage with after reference voltage is compared, if input voltage, then has the voltage comparator output high level or the low level signal of hysteresis characteristic greater than reference voltage.That is to say that voltage comparator is used for comparator input signal.
Voltage comparator with hysteresis characteristic has the point that two outputs change, that is, and and high reference voltage and low reference voltage.
In order to realize avoiding the voltage comparator of noise jamming, voltage comparator should be designed to have hysteresis characteristic.Therefore, if this hysteresis characteristic changes according to process (process), voltage comparator itself will produce mistake, thereby damages whole semi-conductive reliability.
Fig. 1 shows the circuit diagram according to the voltage comparator 100 of prior art.As shown in Figure 1, traditional voltage comparator 100 is made of following parts: by first and second transistors 101 and 102 of input voltage vin driving, third and fourth transistor 103 and 104 by reference voltage V ref driving, be connected with 103 and earth terminal to produce the voltage drop unit 105 of voltage drop with the 3rd transistor 102 with second, be connected with earth terminal so that by the 5th transistor 106 of the driven of voltage drop unit 105 generations with transistor seconds 102, be connected with earth terminal with the 5th transistor 106 so that the 6th transistor 107 that is driven by supply voltage, and with first, the 4th, the 5th, with the 6th transistor 101,104,106 are connected with 103 common port (commonterminal) with the bias component 108 of the constant of holding current with the 3rd transistor 102 with 107 and second.
First to fourth transistor 101 to 104 is made of the PNP transistor, and the 5th and the 6th transistor 106 and 107 is made of NPN transistor.
When 100 pairs of input voltage vin of the voltage comparator with this structure and reference voltage V ref compare so that when exporting high level or low level signal, this process is shown in Figure 2, will describe in detail below.
Fig. 2 shows the chart of the course of work of traditional voltage comparator of the output signal that has correspondingly.(A) shows input voltage vin and the reference voltage V ref of this voltage comparator according to the time among Fig. 2.(B) shows the output signal Vout of this voltage comparator according to the time among Fig. 2.
At first, when input voltage vin during less than reference voltage V ref (at interval A), because the PNP characteristics of transistor make transistor seconds 102 connect, and the 3rd transistor 103 disconnects.Then, the bias current I of voltage comparator 100
1aFlow into I
2aTherefore, in voltage drop unit 105, produce voltage drop, so that constant voltage is applied on the emitter of the 5th transistor 106.At this moment, owing to the threshold voltage of this voltage greater than the 5th transistor 106, institute is so that 106 connections of the 5th transistor.
Therefore, the emitter of the 6th transistor 107 receives the collector emitter voltage of the 5th transistor 106.Because this voltage (about 0.1V) is less than the threshold voltage of the 6th transistor 107, institute is so that the 6th transistor 107 disconnects.
Then, the output of voltage comparator 100 receives supply voltage VDD, so that correspondingly export high level signal (shown in (B) among Fig. 2).
When input voltage vin during greater than reference voltage V ref (in interval B), because the PNP characteristics of transistor make transistor seconds 102 disconnect, and the 3rd transistor 103 is connected.Then, the bias current I of voltage comparator 100
1aFlow into I
3aIn this case, in voltage drop unit 105, do not produce voltage drop, and do not apply the emitter voltage that to connect the 5th transistor 106.Therefore, the 5th transistor 106 disconnects.
Therefore, the emitter of the 6th transistor 107 receives the supply voltage VDD of voltage comparator 100.Then, the 6th transistor 107 is connected, so that low level signal is outputed to the output (shown in (B) among Fig. 2) of voltage comparator 100.
Fig. 3 shows in traditional voltage comparator the chart corresponding to the output signal of input noise.(A) shows input voltage vin and the reference voltage V ref when producing noise in the interval of input voltage vin greater than reference voltage V ref among Fig. 3.(B) shows the output signal when producing noise among Fig. 3.
In stable voltage comparator, even produce noise C in input voltage vin in greater than the input voltage vin in the interval of reference voltage V ref, the output of this voltage comparator still remains on low level.Yet as shown in Figure 3, above-mentioned traditional voltage comparator is consequently exported high level signal in response to noise C.
Summary of the invention
Advantage of the present invention has been to provide a kind of voltage comparator with hysteresis characteristic, wherein add the reference voltage that constitutes by a few components and changed part, so that can design the voltage comparator of avoiding importing noise jamming, and the size of hysteresis voltage can accurately be set and can pass through to change resistance value change simply.
The others and the advantage of total inventive concept of the present invention will be partly articulated in the following description, and partly by this explanation and apparent, perhaps can know by implementing total inventive concept of the present invention.
According to an aspect of the present invention, the voltage comparator with hysteresis characteristic comprises: input voltage and reference voltage are compared so that export the rating unit of high level or low level signal; And the reference voltage that changes reference voltage when from rating unit output low level signal changes part.
This rating unit comprises: by the switching part of input voltage and reference voltage driving; Be connected with earth terminal so that produce the voltage drop unit of voltage drop with this switching part; Be connected so that export the segment signal output of high level or low level signal by output with this voltage drop unit; And be connected with segment signal output so that the bias current part of holding current constant with this switching part.
This switching part comprises: by first and second transistors of input voltage driving; And third and fourth transistor that drives by reference voltage.
This segment signal output comprises: be connected with earth terminal with transistor seconds so that by the 5th transistor that voltage drove of this voltage drop unit generation; And be connected with earth terminal with the 5th transistor so that the 6th transistor that is driven by supply voltage.
First to fourth transistor is the PNP transistor, and the 5th and the 6th transistor is a NPN transistor.
This voltage drop unit is made up of the 7th and the 8th transistor that connects with the current mirror relation.
The the 7th and the 8th transistor is a NPN transistor.
This reference voltage changes part and comprises: the 9th transistor that is connected with third and fourth transistor; First resistance that is connected with the 9th transistor series; And with first resistance, earth terminal and the 5th the tenth transistor that is connected with the 6th transistorized common port.
When input voltage during less than reference voltage, transistor seconds and the 5th transistor are connected, and the 3rd transistor and the 6th transistor disconnect, so that this rating unit is exported high level signal by output.
The tenth transistor that this reference voltage changes part disconnects.
When input voltage during greater than reference voltage, the 3rd transistor of this rating unit and the 6th transistor are connected, and transistor seconds and the 5th transistor disconnect, so that this rating unit is by output output low level signal.
The the 9th and the tenth transistor that this reference voltage changes part is switched on.
This first resistance is the variable resistor that its value can change.
In order to protect the 6th transistor, between the 5th transistorized collector electrode and the tenth transistorized base stage, be connected with second resistance, between the 5th transistorized collector electrode and the 6th transistorized base stage, be connected with the 3rd resistance.
Description of drawings
These and/or other the aspect of total inventive concept of the present invention and advantage will become apparent from the description below in conjunction with the specific embodiment of accompanying drawing and easy to understand more, in the accompanying drawing:
Fig. 1 shows the circuit diagram of traditional voltage comparator;
Fig. 2 shows the chart of the course of work of traditional voltage comparator and output signal correspondingly;
Fig. 3 shows in traditional voltage comparator the chart corresponding to the output signal of input noise;
Fig. 4 shows the circuit diagram according to voltage comparator of the present invention;
Fig. 5 shows the chart according to the hysteresis characteristic of voltage comparator of the present invention; And
Fig. 6 shows the chart corresponding to the output signal of the input noise of this voltage comparator.
Embodiment
Now will be in detail with reference to the embodiment of total inventive concept of the present invention, embodiment is shown in the drawings, wherein, represents identical parts with identical drawing reference numeral all the time.Below in conjunction with these execution modes of description of drawings, so that explain total inventive concept of the present invention.
To describe the preferred embodiments of the present invention in conjunction with the accompanying drawings in detail hereinafter.
Fig. 4 is the circuit diagram that illustrates according to voltage comparator of the present invention.As shown in Figure 4, this voltage comparator comprises: rating unit 400 compares input voltage vin and reference voltage V ref, so that output high level or low level signal; And reference voltage change part 411, when from rating unit 400 output low level signals, it changes reference voltage V ref.
Switching part 401 comprises: third and fourth transistor 401c and the 401d that is transfused to the first and second transistor 401a that voltage Vin drives and 401b and is driven by reference voltage V ref.
First to fourth transistor 401a to 401d is made of the PNP transistor, and the 5th and the 6th transistor 402a and 402b are made of NPN transistor.
Voltage drop unit 405 is made of the 7th and the 8th transistor 405a and the 405b that connect with the current mirror relation.The the 7th and the 8th transistor 405a and 405b are made of NPN transistor.
Reference voltage changes part 411 and comprises: the 9th transistor 412 that is connected with 401d with the third and fourth transistor 401c; First resistance 413 that is connected in series with the 9th transistor 412; And the tenth transistor 414 that is connected with 407 common port with the 6th transistor 406 with first resistance 413, earth terminal and the 5th.
Have only when the voltage that puts on the 6th transistor 402b during, just connect the 6th transistor 402b greater than the threshold voltage (being generally 0.7V) of the 6th transistor 402b.Therefore, when general supply voltage VDD is put on the emitter of the 6th transistor 402b, owing to the voltage that has applied greater than the normal voltage of the 6th transistor 402b, so can damage the 6th transistor 402b.Therefore, between the base stage of the collector electrode of the 5th transistor 402a and the tenth transistor 414, be connected with second resistance 409, and between the base stage of the collector electrode of the 5th transistor 402a and the 6th transistor 402b, be connected with the 3rd resistance 410, thereby prevent from overvoltage is imposed on the emitter of the 6th transistor 402b.
When the voltage comparator with this structure compares with output high level or low level signal to output voltage V in and reference voltage V ref, this process will be described below.
At first, if input voltage vin is less than reference voltage V ref, because the PNP characteristics of transistor make transistor seconds 401b connect, and the 3rd transistor 401c disconnects.Then, the bias current I of voltage comparator
1bFlow into I
2bTherefore, in voltage drop unit 405, produce voltage drop, so that constant voltage is applied on the emitter of the 5th transistor 402a.At this moment, because the size of this voltage is greater than the size of the threshold voltage of the 5th transistor 402a, so the 5th transistor 402a connects.
Therefore, the emitter of the 6th transistor 402b receives the collector emitter voltage of the 5th transistor 402a.Because this voltage (being about 0.1V usually) is less than the threshold voltage of the 6th transistor 402b, the 6th transistor 402b disconnects.At this moment, the emitter of the 6th transistor 402b is connected to the emitter of the tenth transistor 414.Therefore, the collector emitter voltage of the 5th transistor 402a is put on the emitter of the tenth transistor 414, so that the tenth transistor 414 also disconnects.Therefore, when input voltage vin during less than reference voltage V ref, reference voltage changes the not influence at all of 411 pairs of voltage comparators of part.
On the other hand, when input voltage vin during greater than reference voltage V ref, because the PNP characteristics of transistor make transistor seconds 401b disconnect, and the 3rd transistor 401c connects.Then, the bias current I of voltage comparator
1bFlow into I
3bThereby, in voltage drop unit 405, do not produce voltage drop.Therefore, owing to do not apply the emitter voltage that can connect the 5th transistor 402a, so the 5th transistor 402a disconnects.
Therefore, the emitter of the 6th transistor 402b receives the supply voltage VDD of this voltage comparator.Then, the 6th transistor 402b connects low level signal is outputed to the output of this voltage comparator.
At this moment, because the emitter of the 6th transistor 402b links to each other with the emitter of the tenth transistor 414, this supply voltage VDD also is applied on the emitter of the tenth transistor 414.Then, the tenth transistor 414 is connected.
Therefore, electric current flows through the 9th transistor 412, first resistance 413 and the tenth transistor 414.The emitter voltage of the 3rd transistor 401c can be by the emitter base voltage V of the 9th transistor 412
BE, be applied to the voltage V of first resistance, 413 both sides
R1, and the summation of the collector to-boase voltage Vsat of the tenth transistor 414 represent.From this time, reference voltage becomes V
BE+ V
R1+ Vsat (Vref ' hereinafter referred to as).Fig. 5 is the chart that illustrates according to the hysteresis characteristic of voltage comparator of the present invention.Fig. 6 be illustrated in according in the voltage comparator of the present invention corresponding to the chart of output signal of input noise.(A) illustrates when at input voltage vin and the reference voltage V ref of input voltage vin when producing noise in reference voltage V ref interval among Fig. 6, and the output signal when (B) shows this noise of generation among Fig. 6.As shown in Figure 5, when output signal from high level when low level changes, reference voltage is reference voltage V ref, but when output signal from low level when high level changes, reference voltage becomes reference voltage V ref '.
When output signal from high level when low level changes, only just export high level signal under less than the situation of reference voltage V ref ' in input voltage vin.Therefore, voltage comparator according to the present invention has hysteresis characteristic.In addition, as shown in Figure 6, when the noise E that produces less than hysteresis voltage size (between Vref and Vref ' difference), this voltage comparator keeps the low level output corresponding to noise E.
In the voltage comparator with hysteresis characteristic according to the present invention, be added with the reference voltage that constitutes by a few components at the circuit built-in and change part, it makes it possible to design the voltage comparator of avoiding importing noise jamming.
Change part owing to utilize variable resistor to constitute reference voltage, thus the size of this hysteresis voltage can accurately set, and can change easily by the value that changes resistance.
Though illustrated and described several specific embodiments of total inventive concept of the present invention, but those skilled in the art should understand, under the situation of principle that does not depart from total inventive concept of the present invention and spirit, can make amendment to these specific embodiments, the scope of total inventive concept of the present invention is limited by claims and equivalent thereof.
Claims (14)
1. voltage comparator with hysteresis characteristic comprises:
Rating unit compares input voltage and reference voltage, so that output high level or low level signal; And
Reference voltage changes part, changes described reference voltage from described rating unit output low level signal the time.
2. the voltage comparator with hysteresis characteristic according to claim 1, wherein said rating unit comprises:
Switching part by described input voltage and reference voltage driving;
Be connected with earth terminal to produce the voltage drop unit of voltage drop with described switching part;
Be connected with segment signal output with described voltage drop unit by output output high level or low level signal; And
Be connected bias current part with described segment signal output with described switching part with the holding current constant.
3. the voltage comparator with hysteresis characteristic according to claim 2, wherein said switching part comprises:
First and second transistors by described input voltage driving; And
Third and fourth transistor by described reference voltage driving.
4. the voltage comparator with hysteresis characteristic according to claim 3, wherein said segment signal output comprises:
Be connected with earth terminal so that by the 5th transistor that voltage drove of described voltage drop unit generation with described transistor seconds; And
Be connected with earth terminal with described the 5th transistor so that by the 6th transistor that supply voltage drove.
5. the voltage comparator with hysteresis characteristic according to claim 4,
Wherein, described first to fourth transistor is the PNP transistor, and the described the 5th and the 6th transistor is a NPN transistor.
6. the voltage comparator with hysteresis characteristic according to claim 2,
Wherein, described voltage drop unit is made up of the 7th and the 8th transistor that connects with the current mirror relation.
7. the voltage comparator with hysteresis characteristic according to claim 6,
Wherein, the described the 7th and the 8th transistor is a NPN transistor.
8. the voltage comparator with hysteresis characteristic according to claim 5, wherein said reference voltage change part and comprise:
The 9th transistor that is connected with described third and fourth transistor;
First resistance that is connected with described the 9th transistor series; And
With described first resistance, earth terminal and the described the 5th the tenth transistor that is connected with the 6th transistorized common port.
9. the voltage comparator with hysteresis characteristic according to claim 8,
Wherein, when described input voltage during less than described reference voltage, described transistor seconds and the 5th transistor are connected, and described the 3rd transistor and the 6th transistor disconnect, so that make described rating unit export high level signal by output.
10. the voltage comparator with hysteresis characteristic according to claim 9,
Wherein, described reference voltage changes the tenth transistor disconnection of part.
11. the voltage comparator with hysteresis characteristic according to claim 8,
Wherein, when described input voltage during greater than described reference voltage, described the 3rd transistor of described rating unit and the 6th transistor are connected, and described transistor seconds and the disconnection of the 5th transistor, so that make described rating unit by output output low level signal.
12. the voltage comparator with hysteresis characteristic according to claim 11,
Wherein, described reference voltage changes the described the 9th and the tenth transistor connection of part.
13. according to claim 10 or 12 described voltage comparators with hysteresis characteristic,
Wherein, described first resistance is the variable resistor that its value can change.
14. according to claim 10 or 12 described voltage comparators with hysteresis characteristic,
Wherein, in order to protect described the 6th transistor; between the described the 5th transistorized collector electrode and the described the tenth transistorized base stage, be connected with second resistance, and between the described the 5th transistorized collector electrode and the described the 6th transistorized base stage, be connected with the 3rd resistance.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR20050070553 | 2005-08-02 | ||
| KR1020050070553 | 2005-08-02 | ||
| KR1020060028621 | 2006-03-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1909369A true CN1909369A (en) | 2007-02-07 |
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ID=37700380
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200610086548 Pending CN1909369A (en) | 2005-08-02 | 2006-06-20 | Voltage comparator having hysteresis characteristics |
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|---|---|
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103440010A (en) * | 2013-08-27 | 2013-12-11 | 电子科技大学 | Active voltage limiting circuit |
| CN105743466B (en) * | 2016-02-01 | 2018-08-21 | 厦门新页微电子技术有限公司 | A kind of adjustable hysteresis comparator applied to wireless charging control chip |
-
2006
- 2006-06-20 CN CN 200610086548 patent/CN1909369A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103440010A (en) * | 2013-08-27 | 2013-12-11 | 电子科技大学 | Active voltage limiting circuit |
| CN103440010B (en) * | 2013-08-27 | 2015-01-07 | 电子科技大学 | Active voltage limiting circuit |
| CN105743466B (en) * | 2016-02-01 | 2018-08-21 | 厦门新页微电子技术有限公司 | A kind of adjustable hysteresis comparator applied to wireless charging control chip |
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