CN102709900A - Input stage protection circuit - Google Patents
Input stage protection circuit Download PDFInfo
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- CN102709900A CN102709900A CN2012101866040A CN201210186604A CN102709900A CN 102709900 A CN102709900 A CN 102709900A CN 2012101866040 A CN2012101866040 A CN 2012101866040A CN 201210186604 A CN201210186604 A CN 201210186604A CN 102709900 A CN102709900 A CN 102709900A
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Abstract
The invention discloses an input stage protection circuit, which comprises an NPN triode Q1, N diodes D1-DN and a resistor R1, wherein a collecting electrode of the NPN triode Q1 is connected with the input end Vin, an emitting electrode is grounded, the resistor R1 is connected between a base electrode and the emitting electrode of the NPN triode Q1, the N diodes D1-DN are connected in series between the base electrode and the collecting electrode of the NPN triode Q1, a positive electrode of the diode D1 is connected with the collecting electrode of the NPN triode Q1, and a negative electrode of the diode DN is connected with the base electrode of the NPN triode Q1. The input stage protection circuit has the advantages that an effective protection effect is realized when the circuit input stage generates abnormal input signals, the protection voltage can be set according to the protection circuit requirements, in addition, the VZ value can be set to be lower than 5.8V on the premise of not influencing the normal work and the performance of the circuit, the application range is wider than that the ordinary diode, the required area is also smaller, and in addition, the additional territory layer and process steps are not needed.
Description
Technical field
The present invention is a kind of for the IC interior input stage provides the protective circuit of protection, belongs to the semiconductor fabrication techniques field.
Background technology
For the input stage of a lot of integrated circuits; Excessive or other abnormal signal pulses of input signal inevitably can often appear; Excessive or unusual like this input signal is through after amplifying; The instability that will inevitably cause inside circuit perhaps directly causes burning out of input stage, makes circuit malfunction.For this situation; Generally all can increase the protection that a voltage stabilizing didoe is used as input stage, the demand that the designer can have more different circuit designs different voltage stabilizing values, the point of control protection flexibly; Even thereby make input stage that excessive input signal arranged; Also can also can be released when unusual input signal is perhaps arranged, and can not have influence on the stability of circuit or burn out circuit by the voltage-stabiliser tube amplitude limit through voltage-stabiliser tube.
As shown in Figure 1, be a common voltage stabilizing didoe.As the input stage protection, this structural design is simple, and also can play the certain protection effect.Its groundwork principle is: when input signal just often; In the time of promptly within the claimed range of circuit fluctuation, the circuit operate as normal, voltage stabilizing didoe can not worked this moment; And its reverse leakage current size is received about peace at tens, can any influence not arranged to input signal basically; And it is excessive or when abnormal signal occurring when input signal; The voltage stabilizing value that will surpass design; Make voltage-stabiliser tube get into ON state, excessive input signal can be released through voltage-stabiliser tube, makes that the signal of real entering input stage is not too large; Thereby limited the size of input signal, the stable and reliability of the circuit of assurance.
But conventional voltage stabilizing didoe structure but exists various defectives, causes it that certain limitation is arranged.At first, voltage stabilizing didoe realizes being easier to than ratio in higher in the voltage stabilizing value, but in the voltage stabilizing value during less than 5.8V, the puncture of voltage-stabiliser tube is a Zener breakdown, and its leakage current can increase, and is as shown in Figure 2.Will cause just often like this,, thereby influence the operate as normal of circuit because the leakage current of voltage-stabiliser tube causes attenuated input signal at input signal.Secondly, when excessive input signal or abnormal signal occurring, the power consumption on the voltage-stabiliser tube will be bigger, makes the reliability of itself have hidden danger, only if increase its total area greatly, but this appearance can increase whole chip cost again.And; The endophyte resistance ratio of voltage stabilizing didoe is bigger; Can cause like this under big electric current; The voltage that produces on its dead resistance can make that the actual voltage stabilizing value ratio of voltage-stabiliser tube is big under the situation of little electric current, makes the input signal of circuit under big or small current conditions that difference arranged, and is unfavorable for the raising of circuit performance.
Summary of the invention
The object of the invention is to provide a kind of protective circuit of effective input stage protection; Excessive or when unusual input signal occurring when IC interior input stage input signal; This protective circuit is for being provided amplitude limit and protective effect by the inner input stage of protective circuit; Solved in input stage requires than the circuit of small signal amplitudes with the problem of voltage stabilizing didoe, and improved the reliability of protective circuit itself as the leakage current of limited amplitude protection.
The present invention adopts following technical scheme for realizing above-mentioned purpose:
A kind of input stage protective circuit is characterized in that: it comprises NPN triode Q1, a N diode D
1-D
NWith resistance R 1; Said NPN triode Q1 collector electrode connects input Vin, grounded emitter; Said resistance R 1 is connected between said NPN triode Q1 base stage and the emitter; Said N diode D
1-D
NSeries connection between NPN triode Q1 base stage and collector electrode, diode D
1Anode connect the collector electrode of NPN triode Q1, diode D
NNegative electrode connect the base stage of NPN triode Q1.
The present invention is through new input stage protection structure; In conjunction with rational laying out pattern; Can when unusual input signal occurring, play effective protective effect to the input stage of circuit; Protection voltage can be according to by the demand setting of protective circuit, and can be with V under the prerequisite that does not influence circuit operate as normal and performance
ZValue is set to below the 5.8V, and its range of application is wideer than conventional diode, and needed area is also smaller, and does not need extra domain level and processing step.
Description of drawings
Fig. 1 is the general-purpose diode structure chart.
Fig. 2 is that voltage-stabiliser tube is greater than 5.8V with less than 5.8V leakage current comparison diagram.
Fig. 3 is the structure chart of input stage protective circuit of the present invention.
Embodiment
A kind of input stage protective circuit as shown in Figure 3, it comprises NPN triode Q1, a N diode D
1-D
NWith resistance R 1; Said NPN triode Q1 collector electrode connects input Vin, grounded emitter; Said resistance R 1 is connected between said NPN triode Q1 base stage and the emitter; Said N diode D
1-D
NSeries connection between NPN triode Q1 base stage and collector electrode, diode D
1Anode connect the collector electrode of NPN triode Q1, diode D
NNegative electrode connect the base stage of NPN triode Q1.
Wherein, D
1-D
NEffect be similar to the voltage stabilizing didoe among Fig. 1, so D
1-D
NThe number of series connection depends on by the magnitude of voltage of needed protection of protective circuit input stage or amplitude limit i.e. voltage stabilizing value V
ZThe forward voltage drop sum that equals n diode adds NPN pipe emitter junction forward voltage drop, just V
Z=0.7V * n+0.7V.
When abnormal signal appears in input, and the signal amplitude size surpasses the protection voltage V that circuit is provided with
ZValue (is Vin>0.7V during * n+0.7V); NPN triode Q1 will open; Just this protection structure is started working, and too high input will directly be released by NPN triode Q1, makes the signal that gets into input reach amplitude peak; The amplitude peak of input signal is 0.7V * N+0.7V, the V that just sets
ZValue, circuit get into guard mode, thus make enter into by the signal of the inner input stage of protective circuit not too large and cause the unstable of circuit or produce integrity problem.In case abnormal signal disappears, by protective circuit operate as normal again.
The V of this input stage protection structure
ZValue can according to circuit requirements not only can be set to 5.8V and more than, also can be set to below the 5.8V, and not have the big problem of the existing leakage current of conventional diode, its V
ZValue 0.7V * n+0.7V depends primarily on the forward conduction voltage of PN junction, and leakage current is little, and the forward conduction voltage stability is very good.If conventional voltage stabilizing didoe V
Z<5.8V; Its leakage current can increase greatly, reaches several microamperes tens microamperes even, stable non-constant; Can cause like this when input signal is normal; The input end signal decay influence the circuit operate as normal because the electric leakage problem of diode makes, there is not similar problem in structure of the present invention.
Diode D
1-D
NArea does not need too big; Because the voltage on the single diode has only about 0.7V; And above the electric current that flows through base current that the NPN pipe only need be provided with make the voltage on the resistance R 1 reach the needed electric current of 0.7V, so that the area of single diode does not need is too big.And for the NPN triode, owing to get into ON state after its conducting, the pressure drop between its collector and emitter is not too large, common relatively voltage-stabiliser tube, and its power consumption is smaller, and the area that needs also can be less.In addition, the current capacity of NPN triode also is eager to excel more than conventional diode, can more effective playing a protective role.
Claims (1)
1. input stage protective circuit, it is characterized in that: it comprises NPN triode Q1, a N diode D
1-D
NWith resistance R 1; Said NPN triode Q1 collector electrode connects input Vin, grounded emitter; Said resistance R 1 is connected between said NPN triode Q1 base stage and the emitter; Said N diode D
1-D
NSeries connection between NPN triode Q1 base stage and collector electrode, diode D
1Anode connect the collector electrode of NPN triode Q1, diode D
NNegative electrode connect the base stage of NPN triode Q1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012101866040A CN102709900A (en) | 2012-06-07 | 2012-06-07 | Input stage protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012101866040A CN102709900A (en) | 2012-06-07 | 2012-06-07 | Input stage protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN102709900A true CN102709900A (en) | 2012-10-03 |
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ID=46902518
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2012101866040A Pending CN102709900A (en) | 2012-06-07 | 2012-06-07 | Input stage protection circuit |
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| Country | Link |
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| CN (1) | CN102709900A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104253425A (en) * | 2013-06-27 | 2014-12-31 | 上海华虹宏力半导体制造有限公司 | Electrostatic protection structure |
| CN104579191A (en) * | 2014-12-31 | 2015-04-29 | 苏州英诺迅科技股份有限公司 | Standing wave voltage protection circuit for amplifier protection |
| CN110797851A (en) * | 2019-10-11 | 2020-02-14 | 杭州兆鼎科技实业有限公司 | Voltage clamping circuit and electronic equipment thereof |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5742465A (en) * | 1996-04-24 | 1998-04-21 | Winbond Electronics Corporation | Protection circuit for a CMOS integrated circuit |
| US6560081B1 (en) * | 2000-10-17 | 2003-05-06 | National Semiconductor Corporation | Electrostatic discharge (ESD) protection circuit |
| US20070070564A1 (en) * | 2005-09-19 | 2007-03-29 | Yintat Ma | Esd protection circuits for rf input pins |
-
2012
- 2012-06-07 CN CN2012101866040A patent/CN102709900A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5742465A (en) * | 1996-04-24 | 1998-04-21 | Winbond Electronics Corporation | Protection circuit for a CMOS integrated circuit |
| US6560081B1 (en) * | 2000-10-17 | 2003-05-06 | National Semiconductor Corporation | Electrostatic discharge (ESD) protection circuit |
| US20070070564A1 (en) * | 2005-09-19 | 2007-03-29 | Yintat Ma | Esd protection circuits for rf input pins |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104253425A (en) * | 2013-06-27 | 2014-12-31 | 上海华虹宏力半导体制造有限公司 | Electrostatic protection structure |
| CN104579191A (en) * | 2014-12-31 | 2015-04-29 | 苏州英诺迅科技股份有限公司 | Standing wave voltage protection circuit for amplifier protection |
| CN110797851A (en) * | 2019-10-11 | 2020-02-14 | 杭州兆鼎科技实业有限公司 | Voltage clamping circuit and electronic equipment thereof |
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Application publication date: 20121003 |