CN106786453B - A kind of optical module APD protection circuit - Google Patents
A kind of optical module APD protection circuit Download PDFInfo
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- CN106786453B CN106786453B CN201611114101.7A CN201611114101A CN106786453B CN 106786453 B CN106786453 B CN 106786453B CN 201611114101 A CN201611114101 A CN 201611114101A CN 106786453 B CN106786453 B CN 106786453B
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- apd
- resistance
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- optical module
- quick detection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/041—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage using a short-circuiting device
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Abstract
The present invention provides a kind of optical module APD protection circuit, and optical module APD is connected between APD bias output and ground；Protection is electrically connected between APD bias output and ground, constitutes the decompression shunt circuit in parallel with APD, including the reduction of blood pressure in high-speed shunt circuit for detecting the quick detection circuit of APD bias and being triggered by the quick detection circuit；The reduction of blood pressure in high-speed shunt circuit includes NMOS tube Q1 and resistance R；The drain electrode of the NMOS tube Q1 connects APD bias output, source electrode ground connection by resistance R, and grid connects the trigger signal output end of the quick detection circuit.Present invention employs a NMOS tubes to make shunt circuit, once NMOS open entire APD bias outgoing route be equivalent to connect it is a very small load to ground, voltage can be forgotten about it quickly close to 0 and be kept, APD is effectively protected.
Description
Technical field
The present invention relates to optical module protection circuit field, in particular to the optical module APD of a kind of rapid reaction protects circuit.
Background technique
Optical module is in practical applications since the requirement of some artificial maloperations or special test will appear big light incidence
The case where receiving end, the most common case are light sources without the tested optical module of any decaying directly docking, such case docking
Receiving end is will not generally having an impact for PIN tube core, but for APD (avalanche photodide) tube core, in the wink of big light docking
Between due to increasing benefit again will generate biggish photogenerated current, the electric current of usually several mA is easy under tens volts of high pressures effect
The damage of APD tube core is caused, therefore generally has corresponding protection circuit to the optical module that receiving end is APD.
The origin cause of formation damaged under the big light of APD may be summarized to be instantaneous excessive energy impact, and this impact includes over-voltage or mistake
Stream, APD protection circuit are also to start with from quick decompression and current limliting, and existing design is divided into software control and hardware controls at present
Two schemes.
Current existing software control scheme: voltage caused by big light incidence or current anomaly feedback are examined to MCU, MCU
It measures and takes appropriate measures control after exception or close the output of DC-DC, Fig. 1 simply illustrates this control process.
The program has the following problems: feedback signal need to export again control signal by MCU detection, judgement, control signal
Act on DC-DC to come into force and be also required to the time, it is all delay add up cause its response speed when hardware controls slowly
More, typically at least ms rank, this can be described as a critical defect for requiring the APD of quick response to protect, may cause
It designs entirely ineffective, therefore is rarely employed in practical application.
Currently, using more is hardware protection circuit, if Fig. 2 is that hardware controls APD relatively conventional at present is protected
Shield scheme, frame identification division circuit play a protective role.R4 is series connection divider resistance, and in big light incidence, the partial pressure of resistance can
To reduce practical function in the bias of APD, the reduction of bias can reduce gain to while achieve the purpose that reduce electric current, incidence
Light is bigger, and the amplitude of partial pressure and current limliting is also bigger；Pressure difference of the shunt load branch in big light incidence using the both ends R3 is opened high
Triode PNP is pressed, the one end R0 is connected to the C grade of PNP, and there are two types of (1 and 2 connections in corresponding diagram) for the connection of the other end: one is
It is connected to the FB pin of chip, PNP is equivalent to R0 and R1 parallel connection when opening, the feedback regulation function of chip itself is utilized to reduce APD
Bias；Another kind is attached to ground, and PNP, which is used as when opening and connects load, reduces APD bias using the limitation of DC-DC fan-out capability
And it is shunted.
Compared to software control, this hardware plan has in response speed to be significantly improved, the APD under 0dBm incident light
Bias voltage waveform is as shown in Figure 3.
It can be seen that APD bias can be down to a lesser stationary value within hundred us grades of time by such scheme, play
Certain protective effect, but survey discovery and for example directly use the light source pair of 4dBm or so to a certain extent when incident light increases
Protect circuit that will fail when connecing, Fig. 4 is the APD bias voltage waveform of shielding failure moment.
Fig. 4 can intuitively reflect the Railway Project of existing hardware scheme:
(1) response time is still not fast enough, and Fig. 4, which is shown, is possible to that APD is caused to damage in 10us when incident light is excessive,
And the response time of this circuit is at least at hundred us grades.
(2) protection intensity is inadequate, on the one hand it is that protecting effect is related with incident light size, separately that this, which is embodied in two aspects,
It on the one hand is also to possess certain amplitude after APD bias is stablized.
Summary of the invention
The present invention is for current optical module APD protection circuit since reaction time length cannot carry out effectively optical module APD
Protection deficiency, provide it is a kind of reaction more efficiently optical module APD protect circuit.
The present invention is that technical solution used by realizing its purpose is: a kind of optical module APD protection circuit, optical module APD
It is connected between APD bias output and ground；Protection is electrically connected between APD bias output and ground, is constituted in parallel with APD
Decompression shunt circuit, including detecting the quick detection circuit of APD bias and being triggered by the quick detection circuit quick
It is depressured shunt circuit；The reduction of blood pressure in high-speed shunt circuit includes NMOS tube Q1 and resistance R；The drain electrode of the NMOS tube Q1 is logical
It crosses resistance R and connects APD bias output, source electrode ground connection, grid connects the trigger signal output end of the quick detection circuit.
Present invention employs a NMOS tubes to make shunt circuit, once the entire APD bias outgoing route of NMOS unlatching is suitable
In connect it is a very small load to ground, voltage can be forgotten about it quickly close to 0 and be kept, APD is effectively protected.
Further, in above-mentioned optical module APD protection circuit: the quick detection circuit includes PMOS tube Q2, electricity
Hinder R3, resistance R0；The resistance R3 is connected between APD bias output and APD cathode, the source electrode of the PMOS tube Q2 and
Grid is connected with the both ends the resistance R3 respectively, and the drain electrode of the PMOS tube Q2 is grounded by resistance R0, the PMOS tube
The drain electrode of Q2 forms the trigger signal output end of the reduction of blood pressure in high-speed shunt circuit of triggering.
Suitable R3 is taken, when incident light is sufficiently large, pressure difference of the photogenerated current of APD induction in R3 will be such that PMOS opens first
(unsaturation conducting) is opened, choosing suitable R0 can make its both ends have a biggish pressure difference to fully open NMOS (saturation conduction),
The internal resistance very little of NMOS is negligible at this time, and R is a lesser current limiting safeguard resistor, once NMOS in this way opens entire APD
Bias outgoing route be equivalent to connect it is a very small load to ground, voltage can be forgotten about it quickly close to 0 and be kept, while DC-
The electric current of DC output flows through NMOS for substantially all.As long as this design can guarantee that incident light is more than certain value, APD in principle
Bias and electric current all can quickly be dropped to 0 and be kept with essentially identical speed.The result of actual measurement shows that this scheme can be lower than 1us
Time in by APD bias reduce to 0, Fig. 6 give 4dBm light source docking when APD bias voltage waveform.
Further, in above-mentioned optical module APD protection circuit: the quick detection circuit include: U1, resistance R3,
Resistance R5, resistance R6, resistance R7 and resistance R8；The resistance R3 is connected between APD bias output and APD cathode, resistance
R5 and resistance R6 is connected in series between APD bias output and ground and is connected with the one end R3, and resistance R7 and resistance R8 series winding connect
It connects between APD cathode and ground and is connected with the R3 other end, resistance R5 connects the same mutually defeated of comparator U1 with the tie point of resistance R6
Enter to hold, the tie point of resistance R7 and resistance R8 connect the out-phase input terminal of comparator U1；The output end of comparator U1 forms triggering
The trigger signal output end of reduction of blood pressure in high-speed shunt circuit.
Choose suitable R5, R6, R7, R8 so that under normal circumstances comparator output be it is low, when increasing to one under incident light
Comparator overturning output is made to open NMOS to be high using the pressure difference at the both ends R3 when definite value, comparator output high level can reach
VCC (representative value 3.3V) can fully open NMOS, and R is a lesser current limiting safeguard resistor, once NMOS in this way is opened
Entire APD bias outgoing route be equivalent to connect it is a very small load to ground, voltage can be forgotten about it quickly close to 0 and be kept,
The electric current of DC-DC output simultaneously flows through NMOS for substantially all.
Further, in above-mentioned optical module APD protection circuit: further including resistance R2, the resistance R2 is connected in APD
On cathode.R2 is a decompression current-limiting resistance.
The present invention is described in more detail combined with specific embodiments below.
Detailed description of the invention
Fig. 1 is APD software protection schematic diagram in the prior art.
Fig. 2 is existing APD hardware protection circuit schematic diagram.
Fig. 3 protects circuit protection effect picture in 0dbm shown in Fig. 2.
Fig. 4 is to protect circuit protection effect picture shown in Fig. 2 in 4dbm.
Fig. 5 is 1APD of embodiment of the present invention protection circuit diagram (one).
Fig. 6 is 1APD of embodiment of the present invention protection circuit diagram (two).
Fig. 7 is to protect circuit protection effect picture shown in Fig. 5 or Fig. 6 in 4dbm.
Fig. 8 is 2APD of embodiment of the present invention protection circuit diagram (one).
Fig. 9 is 2APD of embodiment of the present invention protection circuit diagram (two).
Specific embodiment
Embodiment 1, the present embodiment are a kind of PMOS+NMOS APD protection circuit, the quick detection part detection APD electricity of PMOS
Flow size, when input light is excessive, the electric current for flowing through APD is big, APD electric current should limit value in 1-2mA, if it exceeds this model
It encloses, then a trigger signal is generated by R0, make NMOS saturation conduction, APD is depressured and is shunted, as shown in Figure 5: quickly detection electricity
Road includes PMOS tube Q2, resistance R3, resistance R0；Resistance R3 is connected between APD bias output and APD cathode, PMOS tube Q2
Source electrode and grid be connected respectively with the both ends resistance R3, the drain electrode of PMOS tube Q2 is grounded by resistance R0, the drain electrode of PMOS tube Q2
Form the trigger signal output end of the reduction of blood pressure in high-speed shunt circuit of triggering.Here, APD bias output and APD cathode are connected to
Between resistance R3 be a sample resistance, be greater than the threshold that PMOS tube Q2 is opened multiplied by its resistance value when flowing through the electric current I of resistance R3
When threshold voltage, PMOS tube Q2 conducting.
Reduction of blood pressure in high-speed shunt circuit includes NMOS tube Q1 and resistance R；The drain electrode of NMOS tube Q1 connects APD bias by resistance R
Output end, source electrode ground connection, grid connect the trigger signal output end of quick detection circuit.
Here, resistance R3 is an APD current sampling resistor, and when electric current is normal, the voltage at the both ends resistance R3 is smaller,
PMOS tube Q2 will not be made to be connected, when incident light is excessive, pressure difference of the photogenerated current of APD induction in R3 will be such that PMOS first turns on
(unsaturation conducting), choosing suitable R0 can make its both ends have a biggish pressure difference to fully open NMOS (saturation conduction), this
When NMOS internal resistance very little it is negligible, and R is a lesser current limiting safeguard resistor, once the entire APD of the unlatching of NMOS in this way is inclined
Pressure outgoing route be equivalent to connect it is a very small load to ground, voltage can be forgotten about it quickly close to 0 and be kept, while DC-DC
The electric current of output flows through NMOS for substantially all.As long as this design can guarantee that incident light is more than certain value in principle, APD is inclined
Pressure and electric current all can quickly be dropped to 0 and be kept with essentially identical speed.In the present embodiment, bypass NMOS conducting resistance is determined by R
It is fixed usually to take tens ohm to arrive ohm levels up to a hundred, and at several kilo-ohms the general APD equivalent resistance under the input of big light
Nurse magnitude, therefore, the bypass of NMOS can be effectively protected APD.The result of actual measurement shows that this scheme can be lower than 1us
Time in by APD bias reduce to 0, Fig. 7 give 4dBm light source docking when APD bias voltage waveform.
In the present embodiment, a current-limiting resistance R2 also can be set in the cathode of APD, APD more further protect
Shield.
In the present embodiment, in order to carry out the protection for having friendship to APD, the electric current of an amount APD carries out immediately after being greater than 1 to 2mA
Decompression shunts, in the present embodiment, the Standard resistance range of resistance R3 between 1K to 2K ohm, the resistance value of resistance R0 also it is fairly small
Between 300-500 ohm can, and current-limiting resistance R is then smaller, takes 50-100 ohm, PMOS tube Q2 and NMOS tube Q1
Select common high-voltage MOS pipe, if the electric current of APD close to 2mA, the G-S pole tension of PMOS tube Q2 be up to 2 to
4V, PMOS tube Q2 will be connected, and the D-G voltage of PMOS tube would fall to close to zero, in this way, the voltage at the drain D of PMOS tube Q2
2 to 4V are up to, is added in the grid G of NMOS tube, NMOS tube Q1 is connected, the APD decompression for carrying out glue is shunted.
For embodiment 2 as shown in figure 8, compared with embodiment one, the present embodiment is a kind of quick comparator+NMOS APD protection
Circuit, reduction of blood pressure in high-speed shunt circuit is as embodiment one, and quick detection circuit is using a quick comparator, by taking
The variation of sample resistance R3 both end voltage makes comparator overturning generate triggering NMOS reduction of blood pressure in high-speed shunt circuit and shunts, has to APD
Effect protection.
In the present embodiment, quick detection circuit comparator U1, resistance R3, resistance R5, resistance R6, resistance R7 and resistance R8；
Resistance R3 is connected between APD bias output and APD cathode, and resistance R5 and resistance R6 are connected in series in APD bias output
Between ground, resistance R7 and resistance R8 are connected in series between APD cathode and ground, and the tie point of resistance R5 and resistance R6, which connect, to be compared
The tie point of the non-inverting input terminal of device U1, resistance R7 and resistance R8 connect the out-phase input terminal of comparator U1；The output of comparator U1
End forms the trigger signal output end of the reduction of blood pressure in high-speed shunt circuit of triggering.
Reduction of blood pressure in high-speed shunt circuit is still the same, including NMOS tube Q1 and resistance R；The drain electrode of NMOS tube Q1 passes through resistance R
APD bias output, source electrode ground connection are connect, grid connects the trigger signal output end of the quick detection circuit.
In the present embodiment, between resistance R5 and the resistance R6 series winding access left end resistance R3 and ground, that is, resistance R3's
Grounded upstream between resistance R7 and resistance R8 series winding access resistance R3 right end and ground, that is, in the downstream of resistance R3 ground connection, divides
The voltage division signals of this two groups of resistance is not drawn to quick comparator input terminal.High pressure NMOS is added in rear class and is exported with comparator
End is used as switching voltage, concatenates a current limiting safeguard resistor R.
The present embodiment principle is substantially similar with embodiment one, the difference is that the implementation of NMOS drive part.Choosing
Take suitable resistance R5, resistance R6, resistance R7, resistance R8 so that under normal circumstances comparator output be it is low, increase when under incident light
Comparator overturning output is made to open NMOS to be high using the pressure difference at the both ends resistance R3 when greatly to certain value, comparator output is high electric
It is flat to can reach VCC (representative value 3.3V), NMOS can be fully opened, protecting effect is the same as example 1.
In the present embodiment, in order to which by APD current limit, between 1~2mA, sample resistance R3 can take 5K-10K ohm,
The value range of current-limiting resistance R is 50-100 ohm, and opposite sample resistance R3 current-limiting resistance R resistance value is smaller.In addition resistance R5, electricity
Hindering R6, resistance R7 and resistance is usually tens K magnitudes or more, meets following formula:
In formula: R3、R5、R6、R7、R8It is the resistance value of resistance R3, resistance R5, resistance R6 and resistance R7, V respectivelyAPDIt is APD
Bias,It is the APD cut-off current of setting, U1+MAXAnd U1-MAXIt is that comparator in-phase end inputs voltage limiting value and compares respectively
Device backward end inputs voltage limiting value.
The present embodiment 1 and embodiment 2 carry out design protection using the feature that the MOSFET opening time is short and conducting internal resistance is small,
Have compared with existing hardware protection response faster, the stronger advantage of protective effect, comparison is such as table 1:
1 APD of table protects the old and new's hardware plan to compare
| Design scheme | APD bias fall time | APD bias declines degree | Protecting effect |
| The prior art | 100us | Stablize in certain amplitude | The excessive failure of incident light |
| The present embodiment 1,2 | 1us | It is reduced to 0 | It is unrelated with incident light size |
The comparison of table 1 shows that the protective value of new departure has and increases substantially, and utmostly ensure that the peace that APD is used
Quan Xing.
Claims (4)
1. a kind of optical module APD protects circuit, optical module APD is connected between APD bias output and ground；Protect circuit connection
Between APD bias output and ground, the shunt circuit in parallel with APD is constituted, the quick detection circuit including detecting APD bias
With the reduction of blood pressure in high-speed shunt circuit by the quick detection circuit triggering；It is characterized by: the reduction of blood pressure in high-speed shunts electricity
Road includes NMOS tube Q1 and resistance R；The drain electrode of the NMOS tube Q1 connects APD bias output by resistance R, and source electrode is grounded,
Grid connects the trigger signal output end of the quick detection circuit；The quick detection circuit includes PMOS tube Q2, resistance
R3, resistance R0；The resistance R3 is connected between APD bias output and APD cathode, the source electrode and grid of the PMOS tube Q2
Pole is connected with the both ends the resistance R3 respectively, and the drain electrode of the PMOS tube Q2 is grounded by resistance R0, the PMOS tube Q2
Drain electrode formed triggering reduction of blood pressure in high-speed shunt circuit trigger signal output end.
2. optical module APD according to claim 1 protects circuit, it is characterised in that: the Standard resistance range of resistance R3 1K extremely
Between 2K, the resistance value of resistance R0 is between 300-500 ohm, and resistance R is between 50-100 ohm.
3. according to claim 1 or in 2, any optical module APD protects circuit, it is characterised in that: it further include resistance R2,
The resistance R2 is connected on APD cathode.
4. optical module APD according to claim 3 protects circuit, it is characterised in that: APD current limit is between 1-2mA.
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| CN111431613B (en) * | 2020-03-20 | 2023-03-21 | 青岛海信宽带多媒体技术有限公司 | Optical module |
| WO2021237409A1 (en) * | 2020-05-25 | 2021-12-02 | 深圳市锐明技术股份有限公司 | Protection circuit, power supply system of hard disk device, and vehicular device |
| CN112117743B (en) * | 2020-10-12 | 2022-08-30 | 武汉海达数云技术有限公司 | APD protection circuit and laser scanner |
| CN112861461B (en) * | 2021-03-05 | 2022-05-17 | 北京华大九天科技股份有限公司 | Abnormity detection method and device for circuit simulation model |
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