Automatic power regulation circuit for optical communication

Abstract

The present invention proposes an automatic power regulation circuit for optical communication, including: a light emitting circuit, a photoelectric conversion circuit, and a power regulation feedback circuit; the photoelectric conversion circuit receives the optical signal emitted by the light emitting circuit, the output end of the photoelectric conversion circuit is connected to the power regulation feedback circuit, and the output end of the power regulation feedback circuit is connected to the control end of the light emitting circuit. The present invention compares the voltage obtained by photoelectric conversion with the threshold of the window comparator, and the comparator of the analog part will output the corresponding signal to the digital logic circuit, and then output twelve bits of data to the bias current circuit to adjust the bias current of the light emitting diode to change the light emitting power of the light emitting diode, and finally keep the voltage signal output by the photodiode near the window common mode level, so as to stably keep the light emitting power of the light emitting diode within the set range and maintain the communication quality.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to an automatic power regulation circuit applied to optical communication. Background Art

[0002] In modern communication systems, optical fiber communication is widely used in high-speed transmission systems due to its advantages such as large information capacity, long relay distance, and fast transmission speed. The two most important devices are light-emitting diodes and photodiodes. The former, as the transmitting part of the optical fiber communication system, converts current into optical power output; while the latter, as the receiving part, converts the received optical power into an electrical signal. For light-emitting diodes, their luminous power is greatly affected by the external environment and has no consistency, which will inevitably lead to a decrease in communication quality. Therefore, it is necessary to introduce an automatic power adjustment circuit to keep the emission power of the light-emitting diode within a certain range when parameters such as temperature and process change. Summary of the invention

[0003] The object of the present invention is to solve at least one of the technical drawbacks.

[0004] Therefore, the purpose of the present invention is to provide an automatic power regulation circuit for optical communication to solve the problem that the light emitting power of the light emitting diode is greatly affected by the external environment, which may lead to a decrease in communication quality.

[0005] In order to achieve the above-mentioned object, the present invention provides an automatic power regulation circuit applied to optical communication, comprising an optical transmission circuit, a photoelectric conversion circuit, and a power regulation feedback circuit; the photoelectric conversion circuit receives an optical signal transmitted by the optical transmission circuit, the output end of the photoelectric conversion circuit is connected to the power regulation feedback circuit, and the output end of the power regulation feedback circuit is connected to the control end of the optical transmission circuit;

[0006] Specifically, the light emitting circuit includes a light emitting diode and a bias current circuit, the light emitting diode is connected to the bias current circuit, the power regulation feedback circuit includes a filter circuit, a current mirror circuit, a window comparator, a digital logic circuit, and a reference generation circuit, the photoelectric conversion circuit is connected to the input end of the current mirror circuit, the output end of the current mirror circuit is connected to the filter circuit, the filter circuit is connected to the window comparator, the window comparator is connected to the digital logic circuit, the reference generation circuit is connected to the threshold setting end of the window comparator, and the input end of the digital logic circuit is connected to the control end of the bias current circuit.

[0007] Furthermore, the bias current circuit is composed of a plurality of bias current sources connected in parallel, one end of each bias current source is respectively connected in series with a grounded control switch, and the other end of each bias current source is connected to the cathode of the light emitting diode.

[0008] Furthermore, the photoelectric conversion circuit is composed of a photodiode and a resistor, and the photodiode and the resistor are connected in series.

[0009] Furthermore, the current mirror circuit is composed of two MOS tubes with gates connected in series, one MOS tube is connected to the input end of the photoelectric conversion circuit, and the other MOS tube is connected to the filter circuit.

[0010] Furthermore, the filtering circuit is composed of a plurality of resistors, and one end of each resistor is connected in series with a resistor switch, and the other end of each resistor is connected to the output end of the current mirror circuit and the input end of the window comparator.

[0011] Furthermore, there are a plurality of window comparators, and the threshold setting end of each window comparator is respectively connected to the reference generating circuit, and the output end of each window comparator is respectively connected to the digital logic circuit.

[0012] Furthermore, the output end of the current mirror circuit is connected to the input end of one of the window comparators.

[0013] Furthermore, the digital logic circuit outputs twelve bits of data to the bias current circuit to adjust the bias current of the light-emitting diode to change the light-emitting power of the light-emitting diode, and ultimately keeps the voltage signal output by the photoelectric conversion circuit near the window common mode level, thereby stably maintaining the light-emitting power of the light-emitting diode within a set range.

[0014] Furthermore, the bias current of the light-emitting diode is controlled by a power regulation feedback circuit. Starting from an initial position, the bias current first enters the window comparator through a large-step search, then approaches a steady-state point through a medium-step search, and finally dynamically stabilizes within a set range in the form of a slow-step search.

[0015] Furthermore, when the power of the light-emitting diode changes with the change of environmental conditions, the voltage value obtained by the photoelectric conversion circuit through photoelectric conversion will also change, and the digital logic circuit will continue to search and adjust in slow-step mode and stabilize the voltage value obtained by photoelectric conversion back to the set range.

[0016] The automatic power regulation circuit applied to optical communication of the present invention has the following beneficial effects:

[0017] 1. The present invention sets a filter circuit to eliminate the noise component on the electrical signal through the filter circuit, thereby greatly improving the adjustment accuracy.

[0018] 2. The present invention compares the voltage obtained by photoelectric conversion with the threshold of the window comparator. The comparator of the analog part will output the corresponding signal to the digital logic circuit, and then output twelve bits of data to the bias current circuit to adjust the bias current of the light-emitting diode to change the light-emitting diode's emitted light power, and finally keep the voltage signal output by the photodiode near the window common mode level, thereby stably maintaining the light-emitting diode's emitted light power within the set range, maintaining the communication quality, and solving the problem that the light-emitting power is greatly affected by the external environment, which will lead to a decrease in communication quality.

[0019] 3. The voltage output by the current mirror circuit of the present invention is converted into voltage through the resistor in the filter circuit, and then the detection range of the photodiode is controlled by the resistor switch. The smaller the resistance, the larger the detection range.

[0020] 4. The circuit structure and control principle of the present invention are simple and can be widely promoted and used.

[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] Figure 1 It is a structural block diagram of the present invention;

[0024] Figure 2 is a circuit architecture diagram of the present invention;

[0025] Figure 3 It is a curve diagram of the change of the output current of the photodiode of the present invention when the light power is adjusted. DETAILED DESCRIPTION

[0026] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0027] The present invention provides an automatic power regulation circuit for optical communication. Figure 1 As shown, it includes an optical transmission circuit 1, a photoelectric conversion circuit 2, and a power regulation feedback circuit 3; the photoelectric conversion circuit 1 receives the optical signal transmitted by the optical transmission circuit 1, the output end of the photoelectric conversion circuit 2 is connected to the power regulation feedback circuit 3, and the output end of the power regulation feedback circuit 3 is connected to the control end of the optical transmission circuit 1.

[0028] Specifically, the light emitting circuit 1 includes a light emitting diode D1 and a bias current circuit IS, the light emitting diode D1 is connected to the bias current circuit IS, the power regulation feedback circuit 3 includes a filter circuit V, a current mirror circuit M, a window comparator EA, a digital logic circuit APC, and a reference generating circuit REF, the photoelectric conversion circuit 1 is connected to the input end of the current mirror circuit M, the output end of the current mirror circuit M is connected to the filter circuit V, the filter circuit V is connected to the window comparator EA, the window comparator EA is connected to the digital logic circuit APC, the reference generating circuit REF is connected to the threshold setting end of the window comparator EA, and the input end of the digital logic circuit APC is connected to the control end of the bias current circuit IS.

[0029] The bias current circuit IS is composed of a plurality of bias current sources connected in parallel. One end of each bias current source is connected in series with a grounded control switch, and the other end of each bias current source is connected to the cathode of the light emitting diode.

[0030] The photoelectric conversion circuit 1 is composed of a photodiode D2 and a resistor, and the photodiode D2 and the resistor are connected in series.

[0031] The current mirror circuit M is composed of two MOS tubes (M1 and M2) with gates connected in series, one MOS tube M1 is connected to the input end of the photoelectric conversion circuit 1, and the other MOS tube M2 is connected to the filter circuit V. The current mirror circuit M converts the mirror current I_MON into a voltage VMON through a resistor. The resistor switch I_MON_RG<4:0> can control the detection range of the photodiode. The smaller the resistance, the larger the detection range.

[0032] The filter circuit V is composed of a plurality of resistors, and one end of each resistor is connected in series with a resistor switch, and the other end of each resistor is connected to the output end of the current mirror circuit M and the input end of the window comparator EA.

[0033] There are multiple window comparators EA, and the threshold setting end of each window comparator EA is respectively connected to the reference generating circuit REF, and the output end of each window comparator EA is respectively connected to the digital logic circuit APC.

[0034] Figure 1 In the embodiment, the number of window comparators is preferably 3. It should be noted that the above preferred values ​​are not intended to limit the scope of the present invention. Figure 1In the figure, the filter circuit V is connected to the negative input terminal of the window comparator EA2, the positive input terminal of the window comparator EA3 is connected to the negative input terminal of the window comparator EA1, the positive input terminal of the window comparator EA2, the negative input terminal of the window comparator EA3, and the positive input terminal of the window comparator EA1 are respectively connected to the reference generation circuit REF, and the input terminals of the window comparator EA1, the window comparator EA2, and the window comparator EA3 are respectively connected to the digital logic circuit APC. The reference generation circuit REF outputs the stable comparison value APC_SET and the window thresholds APC_WINP and APC_WINN of the voltage VMON obtained by photoelectric conversion.

[0035] The output terminal of the current mirror circuit M is connected to the input terminal of one of the window comparators EA.

[0036] The digital logic circuit APC outputs twelve bits of data to the bias current circuit IS to adjust the bias current of the light emitting diode D1 to change the light emitting power of the light emitting diode D1, and finally keeps the voltage signal output by the photoelectric conversion circuit near the window common mode level, thereby stably keeping the light emitting power of the light emitting diode D1 within the set range.

[0037] The bias current of the light-emitting diode D1 is controlled by the power regulation feedback circuit. Starting from the initial position, the bias current first enters the window comparator EA through a large-step search, then approaches the steady-state point through a medium-step search, and finally dynamically stabilizes within the set range in the form of a slow-step search.

[0038] When the power of the light-emitting diode D1 changes with the change of the environmental state, the voltage value obtained by the photoelectric conversion circuit through photoelectric conversion will also change. The digital logic circuit APC will continue to search and adjust in a slow-step mode and stabilize the voltage value obtained by the photoelectric conversion back to the set value.

[0039] Working principle: The emission power of the light-emitting diode D1 is determined by the bias current ISNK. The photoelectric conversion circuit at the receiving end (i.e., the photodiode D2 and the resistor) completes the conversion of the optical signal into the electrical signal, and then eliminates the noise component on the electrical signal through the filtering circuit V. The voltage VMON obtained by the photoelectric conversion is compared with the thresholds (APC_WINP, APC_SET, APC_WINN) of the window comparator (EA1, EA2, EA3). The comparator of the analog part will output the corresponding signal to the digital logic circuit APC, and then output the twelve-bit data apc_counter<11:0> to adjust the bias current ISNK of the light-emitting diode D1 to change the emission light power of the light-emitting diode D1. Finally, the voltage signal VMON output by the photodiode D2 is kept near the window common-mode level VAPC_SET, thereby stably maintaining the emission light power of the light-emitting diode D1 within the set range.

[0040] Figure 3 The graph below shows the change of the photodiode output current IMON during optical power adjustment. The initial current of the light-emitting diode D1 is set by the initial position Bias_set, and the change step and each step time are controlled by the digital logic circuit APC. Compared with the traditional pure analog adjustment scheme, adding a digital circuit can achieve multi-stage adjustment, and the settling time is faster and more accurate. The working process is as follows: Figure 2 As shown, the bias current ISNK is controlled by the automatic power regulation circuit. The I_MON current starts from the initial position Bias_set and first enters the window through a large step search, then approaches the steady-state point through a medium step search, and finally dynamically stabilizes at the set value APC_SET in the form of a slow step search. After normal establishment, as the environmental state changes, the power of the light-emitting diode D1 changes, and the voltage value VMON obtained by photoelectric conversion will change. The digital logic circuit APC will continue to search and adjust in a slow step mode and stabilize the voltage value VMON obtained by photoelectric conversion back to the set range APC_SET. Among them, MOS tubes M1 and M2 form a current mirror, REF is a reference generation circuit, and outputs the stable comparison value APC_SET of VMON and the window thresholds APC_WINP and APC_WINN.

[0041] The present invention compares the voltage obtained by photoelectric conversion with the threshold of the window comparator. The comparator of the analog part outputs a corresponding signal to the digital logic circuit, and then outputs twelve bits of data to the bias current circuit to adjust the bias current of the light-emitting diode to change the emitted light power of the light-emitting diode, and finally keeps the voltage signal output by the photodiode near the window common mode level, thereby stably keeping the emitted light power of the light-emitting diode within the set range, maintaining the communication quality, and solving the problem that the light-emitting power is greatly affected by the external environment, which will lead to a decrease in communication quality.

[0042] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art can change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An automatic power regulation circuit for optical communication, characterized in that: It includes a light emitting circuit, a photoelectric conversion circuit, and a power regulating feedback circuit; the photoelectric conversion circuit receives the light signal emitted by the light emitting circuit, the output end of the photoelectric conversion circuit is connected to the power regulating feedback circuit, and the output end of the power regulating feedback circuit is connected to the control end of the light emitting circuit; Specifically, the light emitting circuit includes a light emitting diode and a bias current circuit, the light emitting diode is connected to the bias current circuit, the power regulation feedback circuit includes a filter circuit, a current mirror circuit, a window comparator, a digital logic circuit, and a reference generation circuit, the photoelectric conversion circuit is connected to the input end of the current mirror circuit, the output end of the current mirror circuit is connected to the filter circuit, the filter circuit is connected to the window comparator, the window comparator is connected to the digital logic circuit, the reference generation circuit is connected to the threshold setting end of the window comparator, and the output end of the digital logic circuit is connected to the control end of the bias current circuit; The voltage obtained by photoelectric conversion is compared with the threshold of the window comparator. The analog comparator will output the corresponding signal to the digital logic circuit, and then output twelve bits of data to the bias current circuit to adjust the bias current of the light-emitting diode to change the light-emitting power of the light-emitting diode. Finally, the voltage signal output by the photodiode is kept near the window common-mode level, thereby stably maintaining the light-emitting power of the light-emitting diode within the set range.

2. The automatic power regulation circuit for optical communication according to claim 1, characterized in that: The bias current circuit is composed of a plurality of bias current sources connected in parallel, one end of each bias current source is respectively connected in series with a grounded control switch, and the other end of each bias current source is connected to the cathode of the light emitting diode.

3. The automatic power regulation circuit for optical communication according to claim 1, characterized in that: The photoelectric conversion circuit is composed of a photodiode and a resistor, and the photodiode and the resistor are connected in series.

4. The automatic power regulation circuit for optical communication according to claim 1, characterized in that: The current mirror circuit is composed of two MOS tubes with gates connected in series, one MOS tube is connected to the input end of the photoelectric conversion circuit, and the other MOS tube is connected to the filter circuit.

5. The automatic power regulation circuit for optical communication according to claim 1, characterized in that: The filter circuit is composed of a plurality of resistors, and one end of each resistor is connected in series with a resistor switch, and the other end of each resistor is connected to the output end of the current mirror circuit and the input end of the window comparator.

6. The automatic power regulation circuit for optical communication according to claim 1, characterized in that: There are multiple window comparators, and the threshold setting end of each window comparator is respectively connected to the reference generation circuit, and the output end of each window comparator is respectively connected to the digital logic circuit.

7. The automatic power regulation circuit for optical communication according to claim 6, characterized in that: The output end of the current mirror circuit is connected to the input end of one of the window comparators.

8. The automatic power regulation circuit for optical communication according to claim 1, characterized in that: The digital logic circuit outputs twelve bits of data to the bias current circuit to adjust the bias current of the light-emitting diode to change the light-emitting power of the light-emitting diode, and finally keeps the voltage signal output by the photoelectric conversion circuit near the window common mode level, thereby stably maintaining the light-emitting power of the light-emitting diode within a set range.

9. The automatic power regulation circuit for optical communication according to claim 1, characterized in that: The bias current of the light emitting diode is controlled by a power regulation feedback circuit. Starting from the initial position, the bias current first enters the window comparator through a large step search, then approaches the steady-state point through a medium step search, and finally dynamically stabilizes within the set range in the form of a slow step search.

10. The automatic power regulation circuit for optical communication according to claim 1, characterized in that: When the power of the light-emitting diode changes with the change of the environmental state, the voltage value obtained by the photoelectric conversion circuit through photoelectric conversion will also change, and the digital logic circuit will continue to search and adjust in a slow-step mode and stabilize the voltage value obtained by the photoelectric conversion back to the set range.

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