Aer control method of driving chip

Abstract

The application relates to the technical field of optical communication, in particular to an AER control method of a driving chip; the AER automatic extinction ratio control function is completed by adding specific digital logic circuits in the design of the driving chip; and the AER function failure problem caused by the too large ground capacitance of the MPD back light monitoring diode or the special code type such as 0101 code type of the traditional AER circuit is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical communication technology, in particular to an AER control method of a driving chip. BACKGROUND

[0002] The traditional AER automatic extinction ratio control function implementation method of the driving chip is to detect the AC current signal of the backlight detection diode MPD, and amplify and compare through the TIA transimpedance amplifier. The circuit structure determines that the input capacitor cannot be too large, otherwise the function will fail. The AER automatic extinction ratio control function is a practical function favored by customers. With the AER function, customers do not need to test and produce cumbersome temperature compensation tables during production. However, few chip manufacturers on the market can achieve stable AER automatic extinction ratio control function, so a new AER automatic extinction ratio control circuit design method of the driving chip is proposed. SUMMARY

[0003] The present application aims at the problem that the traditional AER circuit fails to achieve the AER automatic extinction ratio control function due to the excessive ground capacitance of the backlight monitoring diode MPD or the special code type 0101, and proposes an AER control method of a driving chip, which completes the AER automatic extinction ratio control function by adding a specific digital logic circuit during the design of the driving chip.

[0004] The present application specifically realizes the following contents:

[0005] An AER control method of a driving chip, specifically comprising the following steps:

[0006] Step S1: write 1 to the calibration register, and acquire the corresponding backlight detection diode MPD voltage ADC value according to the acquired current temperature t0 of the driving chip and the set bias current;

[0007] Step S2: calculate the fitting coefficient f and the fitting coefficient g according to the backlight detection diode MPD voltage ADC value, write them to the corresponding latch, and write 0 to the calibration register;

[0008] Step S3: write 1 to the enable register to start the primary AER automatic extinction ratio control function, and write the target extinction ratio ER value to the register;

[0009] Step S4: calculate the driving chip extinction ratio ER value according to the fitting coefficient f, the fitting coefficient g and the current mod modulation current;

[0010] Step S5: comparing the calculated extinction ratio ER value of the driving chip with the set target extinction ratio ER value of the AER register, adjusting the current mod modulation current according to the comparison result until the calculated extinction ratio ER value of the driving chip is equal to the target extinction ratio ER value, and completing the AER automatic extinction ratio control.

[0011] To better implement the present application, further, the step S1 specifically comprises the following steps:

[0012] Step S11: writing 1 to the calibration register;

[0013] Step S12: obtaining the current temperature t0 of the driving chip, turning off the mod modulation current and setting the first bias current, and obtaining the first backlight detection diode MPD voltage ADC value;

[0014] Step S13: obtaining the current temperature t0 of the driving chip, turning off the mod modulation current and setting the second bias current, and obtaining the second backlight detection diode MPD voltage ADC value.

[0015] To better implement the present application, further, the specific operation of the step S2 is: calculating the fitting coefficient f and the fitting coefficient g according to the first backlight detection diode MPD voltage ADC value, the second backlight detection diode MPD voltage ADC value, the first bias current and the second bias current, writing them into the corresponding latch, and writing 0 to the calibration register.

[0016] To better implement the present application, further, after the preliminary AER automatic extinction ratio control calibration is completed in the step S5, the step S6 is performed for accurate AER automatic extinction ratio control calibration, and the step S6 specifically comprises the following steps:

[0017] Step S61: writing 1 to the calibration register, and obtaining the corresponding third backlight detection diode MPD voltage ADC value according to the obtained current temperature t1 of the driving chip and the set third bias current;

[0018] Step S62: calculating the fitting coefficient m and the fitting coefficient n according to the first backlight detection diode MPD voltage ADC value, the second backlight detection diode MPD voltage ADC value, the third backlight detection diode MPD voltage ADC value, the temperature t0, the temperature t1, the first bias current, the second bias current and the third bias current, writing them into the corresponding latch, and writing 0 to the calibration register;

[0019] Step S63: at the temperature t0, setting the first bias current and the second bias current, measuring the corresponding optical power P1 and optical power P2, and the corresponding first backlight detection diode MPD voltage ADC value and second backlight detection diode MPD voltage ADC value, calculating the fitting coefficient d and the fitting coefficient e and writing them into the latch.

[0020] Step S64: write 1 to the enable register, turn on the precise AER automatic extinction ratio control function, and write the target extinction ratio ER value to the register;

[0021] Step S65: calculate the driving chip extinction ratio ER value according to the fitting coefficient d, the fitting coefficient e, the fitting coefficient m, the fitting coefficient n, the fitting coefficient g, the current mod modulation current, the current temperature t, and the current bias current I.

[0022] Step S66: compare the calculated driving chip extinction ratio ER value with the set target extinction ratio ER value of the AER register, and adjust the current mod modulation current according to the comparison result until the calculated driving chip extinction ratio ER value is equal to the target value, and the AER automatic extinction ratio precise control is completed.

[0023] To better realize the present application, further, the specific operation of the step S4 is:

[0024]

[0025] Wherein, ER is the extinction ratio ER value, f is the fitting coefficient, g is the fitting coefficient, I is the bias current, and M is the current mod modulation current.

[0026] To better realize the present application, further, the specific operation of the step S65 is:

[0027]

[0028] Wherein, ER is the extinction ratio ER value, m is the fitting coefficient, n is the fitting coefficient, d is the fitting coefficient, e is the fitting coefficient, g is the fitting coefficient, I is the bias current, M is the current mod modulation current, and t is the temperature.

[0029] The present application has the following beneficial effects:

[0030] The present application adds specific digital logic circuits in the design of the driving chip to complete the AER automatic extinction ratio control function, avoids the problem of AER automatic extinction ratio control function failure caused by the large ground capacitance of the backlight monitoring diode MPD or the special code type such as 0101 code type in the traditional AER circuit, realizes more stable and powerful AER automatic extinction ratio locking function, saves the time for making and verifying the temperature compensation table in use, and greatly saves the use cost. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The present application provides a primary AER automatic extinction ratio control function flowchart.

[0032] Figure 2The precise AER automatic extinction ratio control function flowchart provided by the present application is shown in the schematic diagram.

[0033] Figure 3 The primary AER automatic extinction ratio calibration enabling flowchart provided by the embodiment of the present application is shown in the schematic diagram.

[0034] Figure 4 The precise AER automatic extinction ratio calibration enabling flowchart provided by the embodiment of the present application is shown in the schematic diagram.

[0035] Figure 5 The optical power calibration enabling flowchart provided by the embodiment of the present application is shown in the schematic diagram.

[0036] Figure 6 The primary AER automatic extinction ratio control function enabling flowchart provided by the embodiment of the present application is shown in the schematic diagram.

[0037] Figure 7 The precise AER automatic extinction ratio control function enabling flowchart provided by the embodiment of the present application is shown in the schematic diagram. DETAILED DESCRIPTION

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. It should be understood that the described embodiments are only a part of the embodiments of the present application, not all the embodiments, and therefore should not be regarded as limiting the scope of protection. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application.

[0039] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "set", "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] The English full name and explanation of the proper noun involved in the present embodiment are as follows:

[0041] Moniter photodiode: back light detection diode MPD;

[0042] Modulation Current: chip output modulation current mod;

[0043] Extinction Ratio: Extinction ratio ER means the value of 1 level divided by 0 level, and AER is AutoExtinction Ratio, automatic extinction ratio control.

[0044] Example 1:

[0045] This embodiment provides an AER control method for a driver chip, which specifically includes the following steps:

[0046] Step S1: Write 1 to the calibration register and obtain the corresponding backlight detection diode MPD voltage ADC value based on the obtained current temperature t0 of the driver chip and the set bias current;

[0047] The step S1 specifically includes the following steps:

[0048] Step S11: write 1 to the calibration register;

[0049] Step S12: obtaining the current temperature t0 of the driver chip, turning off the modulated current and setting the first bias current, and obtaining the ADC value of the first backlight detection diode MPD voltage;

[0050] Step S13: obtaining the current temperature t0 of the driver chip, turning off the mod modulation current and setting the second bias current, and obtaining the ADC value of the second backlight detection diode MPD voltage.

[0051] Step S2: Calculate the fitting coefficient f and fitting coefficient g according to the ADC value of the backlight detection diode MPD voltage, write them into the corresponding latch, and write 0 to the calibration register;

[0052] The specific operation of step S2 is: according to the ADC value of the first backlight detection diode MPD voltage, the ADC value of the second backlight detection diode MPD voltage, the first bias current, and the second bias current, calculate the fitting coefficient f and the fitting coefficient g, write them into the corresponding latch, and write 0 to the calibration register.

[0053] Step S3: Write 1 to the enable register to start the primary AER automatic extinction ratio control function and write the target extinction ratio ER value into the register;

[0054] Step S4: Calculate the extinction ratio ER of the driver chip according to the fitting coefficient f, the fitting coefficient g, and the current mod modulation current;

[0055] Step S5: Compare the calculated extinction ratio ER value of the driver chip with the target extinction ratio ER value set in the AER register, and adjust the current mod modulation current according to the comparison result until the calculated extinction ratio ER value of the driver chip is equal to the target extinction ratio ER value, completing the AER automatic extinction ratio control.

[0056] After the preliminary AER automatic extinction ratio control calibration in step S5 is completed, step S6 is performed for precise AER automatic extinction ratio control calibration, which specifically includes the following steps:

[0057] Step S61: write 1 to the calibration register, and acquire the corresponding third back light detection diode MPD voltage ADC value according to the acquired current temperature t1 of the drive chip and the set third bias current;

[0058] Step S62: according to the first back light detection diode MPD voltage ADC value, the second back light detection diode MPD voltage ADC value, the third back light detection diode MPD voltage ADC value, the temperature t0, the temperature t1, the first bias current, the second bias current, and the third bias current, calculate the fitting coefficient m and the fitting coefficient n, write them to the corresponding latch, and write 0 to the calibration register;

[0059] Step S63: at the temperature t0, set the first bias current and the second bias current, measure the corresponding optical power P1 and optical power P2, and the corresponding first back light detection diode MPD voltage ADC value and second back light detection diode MPD voltage ADC value, calculate the fitting coefficient d and the fitting coefficient e and write them to the latch;

[0060] Step S64: write 1 to the enable register to start the precise AER automatic extinction ratio control function, and write the target extinction ratio ER value to the register;

[0061] Step S65: according to the fitting coefficient d, the fitting coefficient e, the fitting coefficient m, the fitting coefficient n, the fitting coefficient g, the current mod modulation current, the current temperature t, and the current bias current I, calculate the drive chip extinction ratio ER value;

[0062] Step S66: compare the calculated drive chip ER value with the set target extinction ratio ER value of the AER register, and adjust the current mod modulation current according to the comparison result until the calculated drive chip extinction ratio ER value is equal to the target value, and the AER automatic extinction ratio precise control is completed.

[0063] In order to better realize the present application, further, the specific operation of step S4 is:

[0064]

[0065] Wherein, ER is the extinction ratio ER value, f is the fitting coefficient, g is the fitting coefficient, I is the bias current, and M is the current modulation mod current.

[0066] In order to better realize the present application, further, the specific operation of step S65 is:

[0067]

[0068] wherein ER is the ER value, m is a fitting coefficient, n is a fitting coefficient, d is a fitting coefficient, e is a fitting coefficient, g is a fitting coefficient, I is a bias current, M is a current modulating current, t is a temperature.

[0069] Working principle: In this embodiment, specific digital logic circuits are added in the design of the driving chip to complete the AER automatic extinction ratio control function; the problem of AER automatic extinction ratio control function failure caused by the large ground capacitance of the backlight monitoring diode MPD or the special code type such as 0101 code type in the traditional AER circuit is avoided.

[0070] Embodiment 2:

[0071] On the basis of the above-mentioned embodiment 1, as shown in Figure 1 , the steps of primary AER automatic extinction ratio control calibration are described.

[0072] In the previously applied patent with the publication number "CN117014066B" and the name "laser screening method, screener, electronic equipment and storage medium", the expression of the laser light output power is proposed as:

[0073] P=(at+c)I+b

[0074] wherein a, b, c are inherent parameters of the laser, a is the slope describing the change of the light emitting efficiency of the laser with temperature, c is the original light emitting efficiency of the laser, b represents the loss of overall optical coupling, t is the temperature, and I is the driving current of the laser.

[0075] The extinction ratio is: ;

[0076] wherein P1 is the light power of the 1 level, P0 is the light power of the 0 level; for the AC coupling circuit, P1=(at+c)*(I bias +0.5*I mod )+b, P0=(at+c)*(I bias -0.5*I mod )+b;

[0077] For the DC (direct current) coupling circuit, P1=(at+c)*(I bias +I mod )+b, P0=(at+c)*I bias +b;

[0078] wherein I bias is the bias current, and I mod is the modulation current.

[0079] The following mainly describes the AC coupling circuit:

[0080] From the characteristics of the photodiode, the output current I_MPD of the back light detection diode MPD of the laser and the output optical power P of the laser are in a linear relationship, I_MPD~P. The current of the back light detection diode MPD is converted into voltage by the chip sampling and then displayed on the chip MPD_ADC. The current and voltage are also in a linear relationship, and the digital ADC display of the voltage is also in a linear relationship. Therefore, MPD_ADC and the optical power P are in a linear relationship. The corresponding expression for each chip application is:

[0081] P=d*MPD_ADC+e;

[0082] Wherein, d, e are fitting coefficients.

[0083] At t0(recommended 25℃), the MPD_ADC calibration of the chip is started, and the modulation current I mod of the chip is turned off at this time. Then, the bias of 25mA and 45mA is set respectively, and the corresponding MPD_ADC is MPD_ADC1 and MPD_ADC2. Then, we have:

[0084] MPD_ADC1=f*25+g;

[0085] MPD_ADC2=f*45+g;

[0086] Calculate f=(MPD_ADC2-MPD_ADC1) / 20;

[0087] g=MPD_ADC1-(MPD_ADC2-MPD_ADC1) / 20*25;

[0088] Save the current fitting coefficient f and the fitting coefficient g.

[0089] After obtaining the relationship, the rough AER automatic extinction ratio control function is obtained.

[0090] ;

[0091] At any time, the current extinction ratio ER value is calculated, which is compared with the target value set by the AER register. The current mod modulation current M is adjusted accordingly, and finally the calculated extinction ratio ER value is equal to the AER set value.

[0092] The other parts of this embodiment are the same as those of the above-mentioned embodiment 1, and will not be described again.

[0093] Embodiment 3:

[0094] The embodiment is based on any of the above embodiments 1-2, as shown in a specific embodiment to precise AER automatic extinction ratio control function is described in detail. Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 、 Figure 7 The precise AER automatic extinction ratio control function is described in detail.

[0095] If the AER automatic extinction ratio control precision is high, the calibration and precise AER automatic extinction ratio control function can be selected and started.

[0096] Because the optical power P= (at+c) I+b at different temperatures, and P=d*MPD_ADC+e;

[0097] Therefore, at different temperatures, MPD_ADC= (mt+n) *I bias +g, so if you want to start precise AER power automatic extinction ratio control, you need to find another temperature point t1 to calibrate MPD_ADC. Assuming 50℃, the chip turns off the modulation current I mod at this time, then set 45mA, read the corresponding MPD_ADC as MPD_ADC3, and combine the results at t0 temperature, we have:

[0098] MPD_ADC1=(m*t0+n)*25+g

[0099] MPD_ADC2=(m*t0+n)*45+g

[0100] MPD_ADC3=(m*t1+n)*45+g

[0101] The formula is applicable to any temperature, and here we only substitute the test results at t0 temperature for calculation, without repeated testing.

[0102] The values of m and n can be solved respectively:

[0103] m=(MPD_ADC3-MPD_ADC2) / 45 / (t1-t0);

[0104] n=(MPD_ADC1-g) / 25-(MPD_ADC3-MPD_ADC2) / 45 / (t1-t0)*t0;

[0105] In addition, the relationship between optical power and MPD_ADC is a linear function, which can be written as:

[0106] P=d*MPD_ADC+e

[0107] And MPD_ADC= (mt+n) *I bias +g

[0108] So P = d * [(mt + n) * I + g] + e bias

[0109] At t0 (recommended 25℃), the light power calibration is performed, and 25mA and 45mA biases are set respectively, and the corresponding light power P1 and P2 and the corresponding MPD_ADC MPD_ADC1 and MPD_ADC2 are measured;

[0110] P1 = d * MPD_ADC1 + e

[0111] P2 = d * MPD_ADC2 + e

[0112] Calculate:

[0113] d = (P2 - P1) / (MPD_ADC2 - MPD_ADC1)

[0114] e = P1 - (P2 - P1) / (MPD_ADC2 - MPD_ADC1) * MPD_ADC1

[0115] Get the light power P (unit is mw) and the parameters in the expression of MPD_ADC, save the current fitting coefficient d and the fitting coefficient e.

[0116] Substitute:

[0117]

[0118] Then calculate the current extinction ratio ER value at any time, compare it with the target value set in the AER register, adjust the current mod modulation current M accordingly, and finally make the calculated extinction ratio ER value equal to the AER set value. When the light power and MPD_ADC are not calibrated, take d = 1, e = 0 to calculate ER, and the AER automatic extinction ratio control function can also be completed.

[0119] The calibration steps of the three samples are shown in Tables 1-3 as follows:

[0120] Table 1 Sample 1 calibration step table

[0121]

[0122] Table 2 Sample 2 calibration step table

[0123]

[0124] Table 3 Sample 3 calibration step table

[0125]

[0126] ​The test results are shown in Table 4 below.

[0127] Table 4 Test results table

[0128]

[0129] More importantly, the present embodiment is applicable to different code types and different MPD capacitance conditions:

[0130]

[0131] The other parts of the present embodiment are the same as any one of Embodiment 1-Embodiment 2 described above, and thus will not be described again.

[0132] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification or equivalent change made according to the technical essence of the present application to the above embodiment falls within the protection scope of the present application.

Claims

1. A method for controlling the AER of a driver chip, characterized in that: The specific steps include: Step S1: Write 1 to the calibration register and obtain the corresponding backlight detection diode MPD voltage ADC value based on the obtained current temperature t0 of the driver chip and the set bias current; Step S2: Calculate the fitting coefficient f and fitting coefficient g according to the ADC value of the backlight detection diode MPD voltage, write them into the corresponding latch, and write 0 to the calibration register; Step S3: Write 1 to the enable register to start the primary AER automatic extinction ratio control function and write the target extinction ratio ER value into the register; Step S4: Calculate the extinction ratio ER value of the driver chip according to the fitting coefficient f, the fitting coefficient g, and the current mod modulation current; Step S5: Compare the calculated extinction ratio ER value of the driver chip with the target extinction ratio ER value set in the AER register, and adjust the current mod modulation current according to the comparison result until the calculated extinction ratio ER value of the driver chip is equal to the target extinction ratio ER value, thereby completing the AER automatic extinction ratio control; The step S1 specifically includes the following steps: Step S11: write 1 to the calibration register; Step S12: obtaining the current temperature t0 of the driver chip, turning off the modulated current and setting the first bias current, and obtaining the ADC value of the first backlight detection diode MPD voltage; Step S13: obtaining the current temperature t0 of the driver chip, turning off the mod modulation current and setting the second bias current, and obtaining the ADC value of the second backlight detection diode MPD voltage; The specific operation of step S2 is: calculating the fitting coefficient f and the fitting coefficient g according to the ADC value of the first backlight detection diode MPD voltage, the ADC value of the second backlight detection diode MPD voltage, the first bias current, and the second bias current, writing them into the corresponding latches, and writing 0 to the calibration register; f=(MPD_ADC2-MPD_ADC1) / (I bias2 -I bias1 ); g=MPD_ADC1-(MPD_ADC2-MPD_ADC1) / (I bias2 -I bias1 )*I bias1 Among them, MPD_ADC1 is the voltage ADC of the first backlight detection diode MPD, MPD_ADC2 is the voltage ADC of the second backlight detection diode MPD, I bias1 is the first bias current, I bias2 is the second bias current; The specific operations of step S4 are: Among them, ER is the extinction ratio ER value, f is the fitting coefficient, g is the fitting coefficient, I is the bias current, and M is the current mod modulation current.

2. The AER control method of a driver chip according to claim 1, characterized in that: After the preliminary AER automatic extinction ratio control calibration is completed in step S5, step S6 is executed to perform precise AER automatic extinction ratio control calibration, and step S6 specifically includes the following steps: Step S61: writing 1 to the calibration register, and obtaining the corresponding ADC value of the third backlight detection diode MPD voltage according to the obtained current temperature t1 of the driver chip and the set third bias current; Step S62: Calculate the fitting coefficients m and n based on the ADC value of the first backlight detection diode MPD voltage, the ADC value of the second backlight detection diode MPD voltage, the ADC value of the third backlight detection diode MPD voltage, the temperature t0, the temperature t1, the first bias current, the second bias current, and the third bias current, write them into the corresponding latches, and write 0 to the calibration register; Step S63: At temperature t0, set the first bias current and the second bias current, measure the corresponding optical power P1 and optical power P2, and the corresponding ADC value of the first backlight detection diode MPD voltage and the second backlight detection diode MPD voltage, calculate the fitting coefficient d and the fitting coefficient e, and write them into the latch; Step S64: writing 1 to the enable register to start the precise AER automatic extinction ratio control function and writing the target extinction ratio ER value into the register; Step S65: Calculate the extinction ratio ER of the driver chip according to the fitting coefficient d, the fitting coefficient e, the fitting coefficient m, the fitting coefficient n, the fitting coefficient g, the current mod modulation current, the current temperature t, and the current bias current I; Step S66: Compare the calculated extinction ratio ER value of the driver chip with the target extinction ratio ER value set in the AER register, and adjust the current mod modulation current according to the comparison result until the calculated extinction ratio ER value of the driver chip is equal to the target value, completing the AER automatic extinction ratio control precision control.

3. The AER control method of a driver chip according to claim 2, characterized in that: The specific operations of step S65 are: Wherein, ER is the extinction ratio ER value, m is the fitting coefficient, n is the fitting coefficient, d is the fitting coefficient, e is the fitting coefficient, g is the fitting coefficient, I is the bias current, M is the current mod modulation current, and t is the temperature.

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