Detector gain control method and device for burst mode optical module

Abstract

The present invention discloses a detector gain control method for a burst mode optical module. The gain control device provides two different gain control voltages. In a point-to-multipoint burst receiving environment of a passive optical network (PON) system, a high gain control voltage is used for a first type of user, and a low gain control voltage is used for a second type of user. The first type of user is a user whose distance is greater than a preset threshold, and the second type of user is a user whose distance is less than the preset threshold. The present invention improves the dynamic response range of the optical module, including higher receiving sensitivity and greater overload receiving power; for burst receiving signals of different intensities, the photocurrent intensity distribution generated by the APD is more concentrated, and this feature helps to improve the performance of the burst TIA or LA; the average gain control voltage of the APD is effectively reduced, and the service life of the chip is extended. The present invention also provides a corresponding detector gain control device for a burst mode optical module.

Description

Technical Field

[0001] The present invention belongs to the field of optical access technology, and more particularly, relates to a detector gain control method and device for a burst mode optical module. Background Art

[0002] Optical module receivers typically use avalanche photodiode (APD) chips to achieve high-sensitivity photodetection. Optical modules control their receiver sensitivity by varying the voltage applied to the APD chip's gain region. Increasing the APD chip's gain control voltage improves the module's receiver sensitivity, but also reduces the module's overload optical power. When the incident light signal intensity exceeds the module's overload optical power, the APD chip can be damaged. Typically, the APD chip's gain control voltage is fixed, set to meet both the module's receiver sensitivity and overload optical power requirements.

[0003] In Passive Optical Network (PON) applications, central office optical modules need to receive high-speed burst optical signals from different users. In a point-to-multipoint topology, the power budgets of different users vary greatly. Optical modules should provide sufficient dynamic range to meet the power budget differences between users, such as Figure 1 As shown in the figure, the optical module's receiving sensitivity limit needs to be improved; on the other hand, the optical module's receiving overload optical power needs to be increased. These requirements pose significant challenges to the design of optical modules for PON systems. In particular, with the continuous increase in burst receive signal rates, such as increasing the single-channel rate to 25 / 50 GBaud, the receiving sensitivity limit of optical modules based on APD detectors has been significantly reduced. To ensure the optical module's receiving sensitivity, if the APD detector is set to a high gain control voltage environment for a long time, the optical module's receiving overload optical power performance will be compromised and the APD chip's service life will be shortened. Summary of the Invention

[0004] In response to the above defects or improvement needs of the prior art, the present invention provides a detector gain control scheme for a burst mode optical module, which uses dynamic adjustment to control the gain voltage value of the APD detector, thereby ensuring the maximum optical module receiving sensitivity and signal reception dynamic range.

[0005] To achieve the above object, according to one aspect of the present invention, there is provided a method for controlling the detector gain of a burst-mode optical module. The gain control device provides two different gain control voltages. In the burst reception environment of the point-to-multipoint upstream of a passive optical network (PON) system, a high gain control voltage is adopted for the first type of users, and a low gain control voltage is adopted for the second type of users. The first type of users are those whose distance is greater than a preset threshold, and the second type of users are those whose distance is less than the preset threshold.

[0006] In an embodiment of the present invention, the adjustment of the gain control voltage is controlled through a gain control voltage switching pin to achieve the switching between the high gain control voltage and the low gain control voltage.

[0007] In an embodiment of the present invention, the gain control voltage switching pin is also multiplexed with a rate switching pin to form a multi-level input control signal, simultaneously achieving the selection of the upstream rate and the selection of the avalanche photodiode (APD) gain control voltage.

[0008] In an embodiment of the present invention, the gain control voltage switching pin is controlled by a PON MAC chip. During the burst protection interval of the upstream signal, the PON MAC chip sets the level of this pin according to the optical signal intensity of the current burst data until the arrival of the next burst data.

[0009] According to another aspect of the present invention, there is also provided a detector gain control device for a burst-mode optical module, including: a first boost chip, a second boost chip, and a voltage control switch. The functions of the first boost chip and the second boost chip are to boost the input voltage Vss to Vapd-1 and Vapd-2 respectively, where Vapd-1 < Vapd-2, Vapd-1 corresponds to the low gain control voltage, and Vapd-2 corresponds to the high gain control voltage. The function of the voltage control switch is to select one of Vapd-1 and Vapd-2 to supply voltage to the APD chip.

[0010] In an embodiment of the present invention, the voltage control switch is electrically connected to the gain control voltage switching pin. The gain control voltage switching pin is used to control the voltage control switch. When the input level of the gain control voltage switching pin is low, the output voltage of the voltage control switch is Vapd-1, and when the input level of the gain control voltage switching pin is high, the output voltage of the voltage control switch is Vapd-2.

[0011] In one embodiment of the present invention, a gain control voltage switching pin is provided on the gold finger of the optical module to provide an input control signal for the voltage-controlled switch. The gain control voltage switching signal and the rate switching signal are multiplexed to form a multi-level input control signal, thereby simultaneously realizing the selection of the uplink rate and the selection of the APD gain control voltage. The rate switching pin is used to provide rate selection control to the burst TIA chip.

[0012] In one embodiment of the present invention, the gain control voltage switching signal is provided by the PON MAC chip. During the burst protection interval of the uplink signal, the PON MAC chip sets the signal level according to the optical signal strength of the current burst data until the next burst data arrives.

[0013] In one embodiment of the present invention, during user registration and online, the PON MAC chip collects the received optical power intensity of different users through the RSSI function, compares the received optical power intensity with the preset threshold intensity, and thus calibrates the corresponding APD_Gain_Select state for each user. When the user's received optical power intensity is greater than the preset threshold intensity, the state is set to Vapd-1 to prevent overload; when the user's received optical power intensity is less than the threshold intensity, the state is set to Vapd-2 to provide better sensitivity.

[0014] In one embodiment of the present invention, when constructing the BWMap of the uplink burst frame, the corresponding APD gain control state is added to each burst signal in the BWMap according to user attribution, including two states, Vapd-1 and Vapd-2, thereby achieving gain control of the burst data.

[0015] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0016] (1) Improved the dynamic response range of the optical module, including higher receiving sensitivity and greater overload receiving power;

[0017] (2) For burst received signals of different intensities, the photocurrent intensity distribution generated by the APD is more concentrated, which helps to improve the performance of the burst TIA (Trans-Impedance Amplifier) ​​or LA (Limited Amplifier);

[0018] (3) Effectively reduces the average gain control voltage of the APD and extends the chip life. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 .Schematic diagram of the distribution of uplink signal receiving optical power in a multi-user access system;

[0020] Figure 2 . Diagram of the detector gain control device for the burst mode optical module;

[0021] Figure 3 : Block diagram of the optical module detector gain control system based on PON MAC in multiplexing mode;

[0022] Figure 4 : Timing diagram of optical module detector gain control based on PON MAC drive. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0024] To address the aforementioned issues of optical module receiving sensitivity and signal receiving dynamic range, the present invention provides a detector gain control device and method for a burst mode optical module. To ensure maximum optical module receiving sensitivity and signal receiving dynamic range, the present invention uses a dynamic adjustment method to control the gain voltage value of the APD detector. The technical solution adopted by the proposed method is:

[0025] (1) The gain control device provides two different gain control voltages. In the burst receiving environment of the uplink point-to-multipoint of the PON system, a high gain control voltage is used for the first type of users; a low gain control voltage is used for the second type of users. The first type of users are users whose distance is greater than a preset threshold. Such users are farther away and have greater losses. The second type of users are users whose distance is less than the preset threshold. Such users are closer and have less losses.

[0026] (2) The gain control voltage is adjusted through the gain control voltage switching pin (APD_Gain_Select pin) to switch between high and low gain control voltages. In addition, the APD_Gain_Select pin can be multiplexed with the rate switching pin (Rate_Select pin) to form a multi-level input control signal, which simultaneously selects the uplink rate and the APD gain control voltage.

[0027] (3) The APD_Gain_Select pin is controlled by the PON MAC chip. During the burst protection interval of the uplink signal, the PON MAC chip sets the level of this pin according to the optical signal strength of the current burst data until the next burst data arrives.

[0028] Specifically, during the user registration and online process, the PON MAC chip collects the received optical power intensity of different users through the RSSI function, compares this received optical power intensity with a preset threshold intensity, and thus calibrates the corresponding APD_Gain_Select state for each user. For example, when the received optical power intensity of a user is greater than the threshold intensity, this state is set to Vapd-1 to prevent overload; when the received optical power intensity of a user is less than the threshold intensity, this state is set to Vapd-2 to provide better sensitivity.

[0029] The central office plans the upstream burst timing for each user, so the user attribution of each burst signal is implicitly included in the BWMap. When constructing the BWMap of the upstream burst frame, the corresponding APD gain control state, including two states of Vapd-1 and Vapd-2, is added to each burst signal in the BWMap according to the user attribution, thereby achieving the gain control of the burst data.

[0030] To implement the above technical solution, the present invention proposes a detector gain control device for a burst-mode optical module, as Figure 2 shown. The device includes: a first boost chip, a second boost chip, and a voltage control switch. The functions of the first boost chip and the second boost chip are to boost the input voltage Vss to Vapd-1 and Vapd-2 respectively, where Vapd-1 < Vapd-2, Vapd-1 corresponds to a low-gain control voltage, and Vapd-2 corresponds to a high-gain control voltage. The function of the voltage control switch is to select one of the voltages of Vapd-1 and Vapd-2 to supply to the APD chip. The APD_Gain_Select pin is used to control the voltage control switch. When the input level of the APD_Gain_Select pin is low, the output voltage of the voltage control switch is Vapd-1; when the input level of the APD_Gain_Select pin is high, the output voltage of the voltage control switch is Vapd-2.

[0031] The APD_Gain_Select pin is set on the optical module gold finger to provide the input control signal for the voltage-controlled switch. In addition, in order to save the number of pins on the optical module gold finger, especially for Combo PON optical modules, the APD_Gain_Select pin and the Rate_Select pin can be further multiplexed. Here, the Rate_Select pin is used to provide rate selection control to the burst TIA chip. The APD_Gain_Select signal and the Rate_Select signal are multiplexed to form a multi-level input control signal, which can simultaneously realize the selection of the upstream rate and the selection of the APD gain control voltage. Specifically, the number of pins corresponding to different types of optical module definitions is different; if the number of pins is sufficient, a separate pin can be reserved for gain control; if the number of pins is tight, it can be multiplexed with the Rate Select pin. The multi-mode 10GPON MAC now provides a Rate_Select control pin to select the upstream rate.

[0032] The multi-level signal includes four different levels, corresponding to the combination modes of '00', '01', '10' and '11', as shown in Table 1. The optical module contains a decoder that decomposes the multi-level signal into separate APD_Gain_Select signals and Rate_Select signals, which are respectively provided to the voltage control switch and the burst TIA chip, such as Figure 3 shown.

[0033] Table 1. APD_Gain_Select / Rate_Select signal multiplexing coding table

[0034] Level number Level Coding APD_Gain_Select status Rate_Select Status 0 00 Low Low 1 01 Low high 2 10 high Low 3 11 high high

[0035] The APD_Gain_Select signal is provided by the PON MAC chip. During the burst protection interval (GuardTime) of the uplink signal, the PON MAC chip sets the signal level according to the optical signal strength of the current burst data until the next burst data arrives. Figure 4 shown.

[0036] During user registration and online, the PON MAC chip uses the RSSI function to collect the received optical power intensity of different users. This received optical power intensity is compared with a preset threshold intensity, thereby calibrating the corresponding APD_Gain_Select state for each user. For example, when the user's received optical power intensity exceeds the threshold intensity, the state is set to Vapd-1 to prevent overload; when the user's received optical power intensity is less than the threshold intensity, the state is set to Vapd-2 to provide better sensitivity. The central office plans the uplink burst timing for each user, so the user affiliation of each burst signal is implicitly included in the BWMap. When constructing the BWMap for the uplink burst frame, the corresponding APD gain control state is added to each burst signal in the BWMap based on the user affiliation, including Vapd-1 and Vapd-2 states, thereby achieving gain control for the burst data.

[0037] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A detector gain control method for a burst mode optical module, It is characterized in that The gain control device provides two different gain control voltages. In the uplink point-to-multipoint burst receiving environment of the passive optical network PON system, a high gain control voltage is used for the first type of users, and a low gain control voltage is used for the second type of users. The first type of users are users whose distance is greater than a preset threshold, and the second type of users are users whose distance is less than the preset threshold. The gain control voltage switching signal is provided by the PON MAC chip. During the burst protection interval of the uplink signal, the PON MAC chip sets the level of the gain control voltage switching signal according to the optical signal strength of the current burst data until the next burst data arrives. During the user registration and online period, the PON MAC chip collects the received optical power intensity of different users through the RSSI function, compares the received optical power intensity with the preset threshold intensity, and thus calibrates the corresponding APD_Gain_Select state for each user. When the user's received optical power intensity is greater than the preset threshold intensity, the state is set to Vapd-1 to prevent overload; when the user's received optical power intensity is less than the threshold intensity, the state is set to Vapd-2 to provide better sensitivity.

2. The detector gain control method of the burst mode optical module according to claim 1, It is characterized in that The gain control voltage is regulated by a gain control voltage switching pin to achieve switching between a high gain control voltage and a low gain control voltage.

3. The detector gain control method of the burst mode optical module according to claim 2, It is characterized in that The gain control voltage switching pin is also multiplexed with the rate switching pin to form a multi-level input control signal, thereby realizing the selection of the uplink rate and the selection of the avalanche photodiode APD gain control voltage at the same time.

4. A detector gain control device for a burst mode optical module, It is characterized in that include: A first boost chip, a second boost chip and a voltage control switch. The first boost chip and the second boost chip are used to boost the input voltage Vss to Vapd-1 and Vapd-2 respectively, wherein Vapd-1 < Vapd-2, Vapd-1 corresponds to a low gain control voltage, and Vapd-2 corresponds to a high gain control voltage. The voltage control switch is used to select one of Vapd-1 and Vapd-2 to supply the APD chip. The gain control voltage switching signal is provided by the PON MAC chip. During the burst protection interval of the uplink signal, the PON MAC chip sets the level of the gain control voltage switching signal according to the optical signal strength of the current burst data until the next burst data arrives. During user registration and online, the MAC chip collects the received optical power intensity of different users through the RSSI function, and compares the received optical power intensity with the preset threshold intensity, so as to calibrate the corresponding APD_Gain_Select state for each user. When the user's received optical power intensity is greater than the preset threshold intensity, the state is set to Vapd-1 to prevent overload; when the user's received optical power intensity is less than the threshold intensity, the state is set to Vapd-2 to provide better sensitivity.

5. The detector gain control device of the burst mode optical module according to claim 4, It is characterized in that The voltage-controlled switch is electrically connected to the gain control voltage switching pin, and the gain control voltage switching pin is used to control the voltage-controlled switch. When the input level of the gain control voltage switching pin is low, the output voltage of the voltage-controlled switch is Vapd-1, and when the input level of the gain control voltage switching pin is high, the output voltage of the voltage-controlled switch is Vapd-2.

6. The detector gain control device of the burst mode optical module according to claim 4, It is characterized in that A gain control voltage switching pin is set on the gold finger of the optical module to provide an input control signal for the voltage control switch. The gain control voltage switching signal is multiplexed with the rate switching signal to form a multi-level input control signal, thereby realizing the selection of the uplink rate and the selection of the APD gain control voltage at the same time. The gain control voltage switching pin is also multiplexed with the rate switching pin, wherein the rate switching pin is used to provide rate selection control to the burst TIA chip.

7. The detector gain control device of the burst mode optical module according to claim 4, It is characterized in that When constructing the BWMap of the uplink burst frame, the corresponding APD gain control state is added to each burst signal in the BWMap according to the user attribution, including two states, Vapd-1 and Vapd-2, so as to realize the gain control of the burst data.

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