CN111193553A - Light path insertion loss self-adaptive radio frequency optical receiver - Google Patents
Light path insertion loss self-adaptive radio frequency optical receiver Download PDFInfo
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- CN111193553A CN111193553A CN202010144184.4A CN202010144184A CN111193553A CN 111193553 A CN111193553 A CN 111193553A CN 202010144184 A CN202010144184 A CN 202010144184A CN 111193553 A CN111193553 A CN 111193553A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
- H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
- H04B10/0795—Performance monitoring; Measurement of transmission parameters
- H04B10/07955—Monitoring or measuring power
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Abstract
The invention relates to a radio frequency optical receiver with adaptive optical path insertion loss.A voltage-controlled radio frequency attenuator and a broadband gain equalization circuit are arranged behind a photoelectric detector and a primary amplifier, and then a secondary amplifier is connected to output radio frequency signals. The bias voltage of the photoelectric detector is connected to the singlechip through the digital signal of the analog-digital converter, and the singlechip obtains a corresponding control voltage signal and then is connected to the voltage-controlled radio frequency attenuator through the digital-analog converter to control the attenuation of the voltage-controlled radio frequency attenuator and adjust the gain to ensure constant output. The invention compensates the gain change caused by the optical path insertion loss by adjusting the voltage-controlled radio frequency attenuator arranged behind the photoelectric detector and the primary amplifier, has no extra optical insertion loss, realizes the optical path self-adaption, and simultaneously reduces or even eliminates the deterioration influence of the introduction of the voltage-controlled radio frequency attenuator on the whole noise coefficient. The cost is significantly lower than the optical path adaptive solution of the existing optical attenuator.
Description
Technical Field
The invention relates to the technical field of radio frequency optical communication, in particular to a radio frequency optical receiver with an adaptive optical path insertion loss.
Background
A typical Radio On Fiber (ROF) communication system includes a Radio frequency optical transmitter, a transmission Fiber, and an optical receiver. The system gain is determined by the amplifier gain in the optical transmitter, the electrical/optical/electrical conversion insertion loss, the optical path insertion loss, and the amplifier gain in the optical receiver. Because the three parameters of the amplifier gain in the optical transmitter, the electric/optical/electric conversion insertion loss and the amplifier gain in the optical receiver are all determined values under the condition of no adjustment, only the optical path insertion loss can change when the transmission distance, the switching mode and the distribution environment change. The change of the optical path insertion loss can be directly fed back to the system gain, and the link gain is fluctuated. In the radio frequency optical communication system, the system gain varies with the variation of the optical path insertion loss, and generally, the optical power insertion loss of 1dB causes the linear variation of the output gain of 2dB of the radio frequency optical communication system.
In order to overcome the influence of the optical path insertion loss change in the radio frequency communication optical path on the system gain fluctuation, an optical path self-adaption technology is developed, and even if the optical path insertion loss change exists in a certain range, the system gain can still be kept unchanged. The optical path insertion loss variation range is the dynamic range of optical power adaptation. The adaptive dynamic range is generally determined based on the upper and lower limits of the rf optical transmission distance. For example, the actual attenuation (i.e. the insertion loss of the optical path) of the light with the wavelength of 1550nm transmitted in the optical fiber is about 0.2dB/km, and the dynamic range of the power change of the optical self-adaptation is set to be at least 4dB to ensure the system gain stability of the light transmitted in the optical fiber at the distance of 0-20 km.
The existing optical path adaptive solution is usually based on a voltage-controlled optical attenuator, which is arranged in front of a photodetector, and in order to ensure a dynamic range of optical path adaptation, when a high-power optical signal is input to a receiving end, the optical attenuator attenuates the optical signal to a constant optical power value. By detecting the bias voltage of the photoelectric detector and controlling the light attenuation value of the voltage-controlled optical attenuator by the singlechip or the operational amplifier according to the bias voltage, the light power value of the photoelectric detector is ensured to be constant, and the stability of the system gain is ensured. But the adaptive adjustment process based on the optical attenuator in the adaptive dynamic range can introduce insertion loss; and the voltage-controlled optical attenuator has basic optical insertion loss of about 1dB when no control voltage is applied. These additional insertion losses result in a reduction in the optical power received by the optical signal, thereby degrading the noise figure of the system.
Disclosure of Invention
The invention aims to provide a radio frequency optical receiver with adaptive optical path insertion loss. The bias voltage of the photoelectric detector is converted into a digital signal through an analog-to-digital converter and is connected to the singlechip, the singlechip analyzes and processes the received digital signal, outputs a corresponding control voltage signal, and then is connected to the adjustable voltage-controlled radio frequency attenuator through the digital-to-analog converter, so that the attenuation is controlled, the gain is adjusted, and the output is constant. The invention compensates the gain change caused by the optical path insertion loss by adjusting the voltage-controlled radio frequency attenuator arranged behind the photoelectric detector and the primary amplifier, has no extra optical insertion loss, realizes the optical path self-adapting function, and simultaneously reduces or even eliminates the deterioration influence of the introduction of the adjustable voltage-controlled radio frequency attenuator on the noise coefficient of the whole system.
The invention designs a radio frequency optical receiver with adaptive light path insertion loss, which comprises a photoelectric detector, an amplifier and an attenuator controlled by a singlechip. The attenuator is an adjustable voltage-controlled radio frequency attenuator, and a broadband gain equalization circuit is connected behind the attenuator. The photoelectric detector is connected with the primary amplifier and then connected with the voltage-controlled radio frequency attenuator and the secondary amplifier, optical signals received by the photoelectric detector are converted into electric signals and then firstly enter the primary amplifier, then enter the broadband gain equalization circuit after passing through the voltage-controlled radio frequency attenuator, and are input into the secondary amplifier after compensating gain flatness and then are amplified to output radio frequency signals; the bias voltage of the photoelectric detector is connected to the single chip microcomputer through the digital signal of the analog-to-digital converter, the single chip microcomputer outputs a corresponding control voltage signal, the control voltage signal is connected to the voltage-controlled radio frequency attenuator through the digital-to-analog converter, the attenuation is controlled, and the gain is adjusted to enable the output of the optical receiver to be constant.
When the insertion loss of the optical path changes, the power of the optical signal received by the photoelectric detector is different, the bias voltage of the photoelectric detector changes along with the change, the analog-to-digital converter digitizes the analog bias voltage and sends the digitized analog bias voltage to the single chip microcomputer, the single chip microcomputer analyzes and checks the table of the current data and outputs a control voltage digital signal to the digital-to-analog converter, the control voltage digital signal is converted into a current appropriate control voltage analog signal to drive the voltage-controlled radio frequency attenuator, the attenuation is properly increased when the received optical power is increased and is properly reduced when the received optical power is decreased, and therefore accurate gain coordinated adjustment is.
The working bandwidth of the voltage-controlled radio frequency attenuator completely covers the frequency band of the transmission signal, and the attenuation range is more than or equal to 2 times of the self-adaptive dynamic range.
The broadband gain equalization circuit is a resistor-capacitor parallel circuit or a resistor-inductor series circuit, and the positive slope gain equalization of the broadband gain equalization circuit is 1 dB-4 dB, so that the gain flatness high-frequency fading of the voltage-controlled radio frequency attenuator is effectively inhibited.
The primary amplifier is a radio frequency amplifier with large gain and low noise, the gain of the primary amplifier is greater than or equal to 20dB, and the noise coefficient of the primary amplifier is less than 3dB, so that the noise coefficient influence caused by the attenuation change of the voltage-controlled radio frequency attenuator is counteracted.
The secondary amplifier is a high-linearity radio frequency amplifier, the output 1dB compression point is larger than 18dBm, and the output third-order cut-off point is larger than 36dBm, so that good output of a link is ensured.
The analog-to-digital converter is a 12-bit high-precision analog-to-digital converter, and the digital-to-analog converter is a 12-bit high-precision digital-to-analog converter, and the precision of the digital-to-analog converter is at least 2 mV.
Compared with the existing optical path adaptive solution based on the optical attenuator, the optical path insertion loss adaptive radio frequency optical receiver has the following advantages: 1. the voltage-controlled radio frequency attenuator is used for matching with a broadband gain equalization circuit to realize power self-adaptation, so that the frequency band limitation of the radio frequency attenuator with poor gain flatness is overcome; 2. the cost is low, and compared with an expensive optical attenuator, the voltage-controlled radio frequency attenuator is low in price and remarkably reduced in cost; 3. the voltage-controlled radio frequency attenuator is low in noise, is arranged after the electric signal converted by the photoelectric detector is primarily amplified, compensates for gain change caused by optical path insertion loss, does not influence the noise coefficient of an optical receiver, does not introduce extra optical path insertion loss, and can weaken or even eliminate the influence of an optical path self-adaptive function on the noise coefficient; 4. the voltage-controlled radio frequency attenuator can be directly integrated with the primary amplifier and the secondary amplifier, and extra optical fiber connection and optical connectors are not introduced; 5. the reliability is high, and the reliability of the chip device is superior to that of an independent optical attenuator module; 6. the voltage-controlled radio frequency attenuator can be used for gain adjustment, and the optical receiver is added with a gain adjustment function.
Drawings
Fig. 1 is a schematic diagram of an overall structure of an embodiment of the optical path insertion loss adaptive rf optical receiver.
Detailed Description
The present invention will be described in further detail with reference to the following specific embodiments and the accompanying drawings.
The radio frequency optical receiver with the adaptive optical path insertion loss comprises a photoelectric detector, a primary amplifier, a voltage-controlled radio frequency attenuator, a broadband gain equalization circuit and a secondary amplifier which are sequentially connected, as shown in figure 1.
Optical signal S received by the photodetectorinAfter being converted into electric signals, the signals enter a primary amplifier, pass through a voltage-controlled radio frequency attenuator and a broadband gain equalization circuit, enter a secondary amplifier, are amplified and then output radio frequency signals Sout(ii) a The photoelectric detector is characterized by further comprising an analog-digital converter (ADC), a single chip microcomputer and a digital-analog converter (DAC), wherein the bias voltage of the photoelectric detector is connected into the single chip microcomputer through digital signals of the ADC, the single chip microcomputer obtains corresponding control voltage signals, the control voltage signals are connected into the voltage-controlled radio frequency attenuator through the digital-analog converter, and the attenuation of the voltage-controlled radio frequency attenuator is adjusted in real time.
The transmission signal of the embodiment is S-band and the adaptive dynamic range is 4dB, so the working bandwidth of the voltage-controlled radio frequency attenuator selected in the embodiment completely covers the S-band, and the attenuation range is 10 dB.
The primary amplifier is a high-gain and low-noise radio frequency amplifier, the gain of the primary amplifier is 21dB, and the noise coefficient of the primary amplifier is less than 3 dB.
The broadband gain equalization circuit is a resistor-capacitor parallel circuit, or a resistor-inductor series circuit, so that 1 dB-4 dB positive slope gain equalization is achieved, and high-frequency fading of gain flatness of the voltage-controlled radio frequency attenuator is effectively inhibited.
The secondary amplifier of the embodiment is a high-linearity radio frequency amplifier, the 1dB compression point of the output is 20dBm, and the third-order cut-off point of the output is 40 dBm.
The ADC is a 12-bit high-precision analog-to-digital converter, the DAC is a 12-bit high-precision digital-to-analog converter, and the precision of the ADC and the DAC reaches 2 mV.
Compared with the present embodiment, the optical receiver of the existing optical power adaptive system based on the optical attenuator is taken as a comparative example, the frequency band of the device to be tested is 30 MHz-3 GHz, the noise coefficient is 12dB when the optical attenuator is not directly connected, different optical power adaptive dynamic ranges are simulated according to two design schemes, and the test data are shown in Table 1.
TABLE 1 COMPARATIVE TABLE OF NOISE COEFFICIENT DEGRADATION INDICATORS FOR COMPARATIVE EXAMPLE AND THE EXAMPLE HAVING DIFFERENT OPTICAL POWER ADAPTATION RANGES
As can be seen from table 1, the noise figure deterioration of the embodiment of the present invention is significantly smaller than that of the comparative example at different transmission distances, i.e. different adaptive dynamic ranges, and it is seen that the optical path insertion loss adaptive rf optical receiver of the present invention has no extra insertion loss in the optical path, and the gain adjustment is performed after the primary amplifier, so that the optical path adaptation function is implemented while the link noise figure deterioration caused by the introduction of the function is reduced or even eliminated.
The above-described embodiments are only specific examples for further explaining the object, technical solution and advantageous effects of the present invention in detail, and the present invention is not limited thereto. Any modification, equivalent replacement, improvement and the like made within the scope of the disclosure of the present invention are included in the protection scope of the present invention.
Claims (6)
1. An optical path insertion loss adaptive radio frequency optical receiver comprises a photoelectric detector, an amplifier and an attenuator controlled by a single chip microcomputer, and is characterized in that:
the attenuator is a voltage-controlled radio frequency attenuator, and a broadband gain equalization circuit is connected behind the attenuator; the photoelectric detector is connected with the primary amplifier and then connected with the adjustable voltage-controlled radio frequency attenuator, the broadband gain equalization circuit and the secondary amplifier; after the optical signal received by the photoelectric detector is converted into an electric signal, the electric signal firstly enters a primary amplifier, enters a broadband gain equalization circuit after passing through an adjustable voltage-controlled radio frequency attenuator, and then is amplified by a secondary amplifier to output a radio frequency signal;
the bias voltage of the photoelectric detector is connected to the single chip microcomputer through the digital signal of the analog-to-digital converter, and the single chip microcomputer obtains a corresponding control voltage signal and then is connected to the voltage-controlled radio frequency attenuator through the digital-to-analog converter.
2. The optical path insertion loss adaptive radio frequency optical receiver according to claim 1, wherein:
the working bandwidth of the voltage-controlled radio frequency attenuator completely covers the frequency band of the transmission signal, and the attenuation range is more than 2 times of the self-adaptive dynamic range.
3. The optical path insertion loss adaptive radio frequency optical receiver according to claim 1, wherein:
the broadband gain equalization circuit is a resistor-capacitor parallel circuit or a resistor-inductor series circuit, and the positive slope gain equalization of the broadband gain equalization circuit is 1 dB-4 dB.
4. The optical path insertion loss adaptive radio frequency optical receiver according to claim 1, wherein:
the primary amplifier is a high-gain and low-noise radio frequency amplifier, the gain of the primary amplifier is greater than or equal to 20dB, and the noise coefficient of the primary amplifier is less than 3 dB.
5. The optical path insertion loss adaptive radio frequency optical receiver according to claim 1, wherein:
the secondary amplifier is a high-linearity radio frequency amplifier, the 1dB compression point of the output is larger than 18dBm, and the third-order cut-off point of the output is larger than 36 dBm.
6. The optical path insertion loss adaptive radio frequency optical receiver according to claim 1, wherein:
the analog-to-digital converter is a 12-bit high-precision analog-to-digital converter, and the digital-to-analog converter is a 12-bit high-precision digital-to-analog converter, and the precision of the digital-to-analog converter is at least 2 mV.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010144184.4A CN111193553A (en) | 2020-03-04 | 2020-03-04 | Light path insertion loss self-adaptive radio frequency optical receiver |
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| CN202010144184.4A CN111193553A (en) | 2020-03-04 | 2020-03-04 | Light path insertion loss self-adaptive radio frequency optical receiver |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113676257A (en) * | 2021-08-19 | 2021-11-19 | 青岛海信宽带多媒体技术有限公司 | Optical module and optical module automatic gain control method |
| CN115426052A (en) * | 2022-11-04 | 2022-12-02 | 之江实验室 | Overload protection device and method for optical module receiving end |
| CN116320329A (en) * | 2023-05-10 | 2023-06-23 | 深圳芯迈微科技有限公司 | Integrated chip of optical fiber access terminal system |
| CN116647209A (en) * | 2023-07-20 | 2023-08-25 | 成都明夷电子科技有限公司 | Novel millimeter wave digital attenuator |
-
2020
- 2020-03-04 CN CN202010144184.4A patent/CN111193553A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113676257A (en) * | 2021-08-19 | 2021-11-19 | 青岛海信宽带多媒体技术有限公司 | Optical module and optical module automatic gain control method |
| CN115426052A (en) * | 2022-11-04 | 2022-12-02 | 之江实验室 | Overload protection device and method for optical module receiving end |
| CN116320329A (en) * | 2023-05-10 | 2023-06-23 | 深圳芯迈微科技有限公司 | Integrated chip of optical fiber access terminal system |
| CN116320329B (en) * | 2023-05-10 | 2023-09-15 | 深圳芯迈微科技有限公司 | Integrated chip of optical fiber access terminal system |
| CN116647209A (en) * | 2023-07-20 | 2023-08-25 | 成都明夷电子科技有限公司 | Novel millimeter wave digital attenuator |
| CN116647209B (en) * | 2023-07-20 | 2023-10-10 | 成都明夷电子科技有限公司 | Novel millimeter wave digital attenuator |
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