CN115051752A - Communication link and bandwidth expanding method of fluorescent LED in communication link - Google Patents
Communication link and bandwidth expanding method of fluorescent LED in communication link Download PDFInfo
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Abstract
The present disclosure provides a bandwidth expanding method for a fluorescent LED in a communication link, including: operation S1: constructing an original communication link based on a fluorescent LED light source; operation S2: adding a passive equalization circuit in the original communication link, and performing equalization processing on an input electric signal through the passive equalization circuit to suppress yellow light response of the fluorescent LED; and operation S3: and an active equalization circuit is added, and the active equalization circuit is used for inhibiting the low-frequency signal of the input electric signal and amplifying the high-frequency signal, so that the bandwidth expansion of the fluorescent LED in the communication link is realized.
Description
Technical Field
The disclosure relates to the technical field of optical communication, in particular to a communication link and a bandwidth expanding method of a fluorescent LED in the communication link, which can expand the bandwidth of a high-power fluorescent LED without a filter.
Background
With the development of optical wireless communication technology, visible light communication is receiving more and more attention. Compared with the traditional radio frequency communication, the visible light communication has stronger anti-electromagnetic interference characteristic, and has huge unmanaged frequency spectrum resources due to the fact that the visible light wave band is used for information transmission. In addition, the visible light communication uses an LED as a system light source, and the LED is commonly used for illumination, so that the visible light communication can meet the requirements of illumination and communication at the same time, which significantly reduces the power consumption of the communication system.
Fluorescent LEDs are widely used for indoor illumination due to their advantages of low cost and low complexity, and therefore, fluorescent LEDs are commonly used as light sources at the emitting end of a system for indoor visible light communication. The fluorescent LED generates blue light through spontaneous radiation of a PN junction, the blue light excites the fluorescent powder, the fluorescent powder is excited and radiated to generate yellow light, and the yellow light and the blue light are mixed to form white light. Because the phosphor powder has afterglow in luminescence, the response of yellow light generated by stimulated radiation is slow, and therefore the yellow light only enhances the response of the fluorescent LED at low frequency. In addition, in order to meet the requirement of illumination, high-power (> 1W) LEDs are commonly used as light sources in the indoor visible light communication technology, but the modulation bandwidth of the high-power LEDs is narrow, and it is difficult to support high-speed data transmission. Therefore, for a visible light communication system using a high-power fluorescent LED, the existing bandwidth expansion scheme is limited by its own disadvantages, and it is difficult to realize a high-speed visible light communication system.
Disclosure of Invention
Technical problem to be solved
Based on the above problems, the present disclosure provides a communication link and a bandwidth expansion method for a fluorescent LED in the communication link, so as to alleviate technical problems in the prior art that a modulation bandwidth of a high-power fluorescent LED is very narrow, and it is difficult to implement high-speed visible light communication.
(II) technical scheme
In one aspect of the present disclosure, a method for expanding a bandwidth of a fluorescent LED in a communication link is provided, including: operation S1-operation S3.
Operation S1: constructing an original communication link based on a fluorescent LED light source;
operation S2: adding a passive equalization circuit in the original communication link, and performing equalization processing on an input electric signal through the passive equalization circuit to suppress yellow light response of the fluorescent LED; and
operation S3: and an active equalization circuit is added, and the active equalization circuit is used for inhibiting the low-frequency signal of the input electric signal and amplifying the high-frequency signal, so that the bandwidth expansion of the fluorescent LED in the communication link is realized.
According to an embodiment of the present disclosure, operation S2 includes: operation S21: determining amplitude-frequency response | H of passive equalization circuit passive (j ω) |; to be provided withAnd operation S22: according to amplitude-frequency response | H of the passive equalization circuit passive (j ω) | configures the passive equalization circuit.
According to an embodiment of the present disclosure, operation S21 includes: operation S211: measuring a first amplitude-frequency response | H (j ω) | of a fluorescent LED in an original communication link; operation S212: measuring a second amplitude frequency response | H' (j ω) | in the case where a blue filter is used after the fluorescent LED; and operation S213: obtaining an amplitude-frequency response difference value | delta H (j omega) | according to the first amplitude-frequency response | H (j omega) | and the second amplitude-frequency response | H' (j omega) | so as to determine the amplitude-frequency response | H (j omega) | of the passive equalization circuit passive (jω)|。
According to the embodiment of the disclosure, in operation S22, the amplitude-frequency response | H of the passive equalization circuit is changed by changing the corresponding zero pole and gain of the passive equalization circuit passive (jω)|。
According to an embodiment of the present disclosure, operation S3 includes: operation S31: measuring a third amplitude frequency response | H' (j omega) | of the LED after the passive equalization circuit is cascaded with the fluorescent LED; operation S32: according to the third amplitude-frequency response | H '(j omega) |, and a target gain G given by the communication link, determining the amplitude-frequency response | H' of the active equalization circuit active (j ω) |; and operation S33: according to amplitude-frequency response | H of the active equalization circuit active (j ω) |, configuring the active equalization circuit.
According to the embodiment of the disclosure, in operation S32, after obtaining the third amplitude-frequency response and the given target gain G, the amplitude-frequency response | H of the active equalization circuit is obtained by the following formula active (jω)|：
20log 10 (|H active (jω)|×|H″(jω)|)＝G。
According to the embodiment of the disclosure, in operation S33, amplitude-frequency response | H of the active equalization circuit is determined active (j ω) |, a pole-zero corresponding to the active equalization circuit is configured to obtain an element setting parameter of the active equalization circuit under the condition of meeting the given target gain G.
In another aspect of the present disclosure, a communication link is provided, including: a light source, a passive equalization circuit, and an active equalization circuit.
Wherein, the light source is a fluorescent LED; the passive equalization circuit is used for performing equalization processing on the input electric signal so as to inhibit yellow light response of the fluorescent LED; the active equalization circuit is used for suppressing a low-frequency signal of an input electric signal and amplifying a high-frequency signal so as to realize bandwidth expansion of the fluorescent LED in the communication link.
According to the embodiment of the disclosure, the passive equalization circuit is improved based on a fixed-resistance bridge T-type network.
According to an embodiment of the disclosure, the active equalization circuit comprises a first equalization branch Z c And a second equalizing branch Z e . Wherein the first equalizing branch Z c Composed of a resistor and an inductor for suppressing low-frequency signals of the input electrical signals, the equalizing branch Z c A collector connected to the NPN transistor; second equalizing branch Z e Composed of a resistor and a capacitor for amplifying high-frequency signal of input electric signal, and an equalizing branch Z e Is connected to the emitter of the NPN transistor.
(III) advantageous effects
From the above technical solution, the communication link and the bandwidth expanding method of the fluorescent LED in the communication link of the present disclosure have at least one or a part of the following beneficial effects:
(1) the method that a blue filter is used for filtering yellow light components in a fluorescent LED in the prior art is abandoned, the influence of yellow light components at a low frequency position is inhibited by using a passive equalization circuit, and the passive equalization circuit does not introduce attenuation to optical signals like the blue filter, so that the passive equalization circuit does not introduce large loss to high-frequency signals while offsetting strong response at the low frequency position;
(2) the active equalization circuit combines the bandwidth expansion technologies of inhibiting the low-frequency signal and amplifying the high-frequency signal at the same time, can inhibit the low-frequency signal and amplify the high-frequency signal at the same time, can effectively avoid the defects of the two bandwidth expansion technologies, has adjustable gain, improves the flexibility of a visible light communication system in the design process, and can simply and efficiently realize a high-speed visible light communication system by using the active equalization circuit.
Drawings
FIG. 1 is a schematic diagram illustrating a bandwidth expansion method for a fluorescent LED in a communication link according to an exemplary embodiment of the disclosure;
FIG. 2 is a flow chart of a method for bandwidth expansion of a fluorescent LED in a communication link according to an embodiment of the present disclosure;
fig. 3 is a schematic diagram of a passive equalization circuit according to an embodiment of the present disclosure;
fig. 4 is a schematic diagram of an active equalization circuit according to an embodiment of the disclosure;
fig. 5 is a schematic circuit diagram of a communication link system according to an embodiment of the disclosure;
Detailed Description
The utility model provides a communication link and a bandwidth expansion method of a fluorescent LED in the communication link, which does not need an optical filter, firstly, an input signal is preprocessed through a passive equalization circuit to replace a blue optical filter to inhibit the response of yellow light so as to eliminate the influence of stronger yellow light component of the fluorescent LED on the amplitude-frequency response characteristic; and then, an input low-frequency signal is inhibited through an active equalization circuit based on an inductor and a capacitor, and an input high-frequency signal is amplified, so that the bandwidth expansion of the high-power fluorescent LED is realized. The bandwidth expansion method can be at least used for solving the problems that the blue filter attenuates high-frequency signals and the existing bandwidth expansion technology is limited in equalization capacity.
In the process of implementing the present disclosure, the inventor finds that the existing bandwidth expansion technologies for a high-power fluorescent LED are mainly divided into two main categories, one is to suppress a low-frequency signal through passive equalization and further improve the modulation bandwidth of the LED, and the other is to amplify a high-frequency signal through active equalization so as to compensate the attenuation of the high-frequency signal by the LED. In addition, in order to eliminate the influence of yellow light components in the fluorescent LED, the two bandwidth expansion technologies are often used in combination with a blue filter, and yellow light generated by the fluorescent LED is filtered by the blue filter, so that the complexity of the design of the equalizing circuit is reduced. However, the technical route of combining the equalization circuit with the blue filter is not suitable for a high-speed visible light communication system, because the blue filter is used for filtering out yellow light components, but inevitably causes attenuation of blue light components, which results in loss of high-frequency signals, which is more valuable for the visible light communication system. The two bandwidth expansion technologies have inherent defects, along with the increase of the expanded bandwidth, the signal-to-noise ratio of an optical signal generated by the LED is deteriorated in a mode of inhibiting a low-frequency signal to improve the LED modulation bandwidth, and the gain requirement on the equalization circuit is increased in a mode of amplifying a high-frequency signal to improve the LED modulation bandwidth, so that the design difficulty of the equalization circuit is increased. To realize high-speed data transmission, not only the limitation of modulation bandwidth is overcome, but also the influence of yellow light at low frequency is eliminated. Accordingly, the present disclosure provides a communication link and a bandwidth extension method for a fluorescent LED in the communication link.
For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.
In an embodiment of the present disclosure, a method for expanding a bandwidth of a fluorescent LED in a communication link is provided, which is shown in fig. 1 to 5, and includes:
operation S1: constructing an original communication link based on a fluorescent LED light source;
in the embodiment of the disclosure, a visible light communication link using a high-power fluorescent LED as a light source is firstly established, and a network analyzer is used to perform frequency characteristic scanning on the visible light communication link to obtain an amplitude response curve in a specific frequency range, so that the amplitude-frequency response | H (j ω) | of the high-power fluorescent LED can be obtained;
further, a blue filter is placed at the back side of the fluorescent LED in the visible light communication link, yellow light components generated by the fluorescent LED are filtered, the amplitude-frequency characteristic of the visible light communication link at the moment is measured, and the amplitude-frequency response | H' (j ω) | of the LED using the blue filter is obtained, wherein ω is angular frequency, and ω is equal to 2 π f and is a variable related to frequency f.
Operation S2: adding a passive equalization circuit in an original communication link, and performing equalization processing on an input electric signal through the passive equalization circuit to suppress yellow light response of a fluorescent LED;
in an embodiment of the present disclosure, operation S2 includes:
operation S21: determining amplitude-frequency response | H of passive equalization circuit passive (j ω) |; and
operation S22: according to amplitude-frequency response | H of the passive equalization circuit passive (j ω) | configures the passive equalization circuit.
Optionally, operation S21, includes:
operation S211: measuring a first amplitude-frequency response | H (j ω) | of a fluorescent LED in an original communication link;
operation S212: measuring a second amplitude frequency response | H' (j ω) | in the case where a blue filter is used after the fluorescent LED; and
operation S213: obtaining an amplitude-frequency response difference value | delta H (j omega) | according to the first amplitude-frequency response | H (j omega) | and the second amplitude-frequency response | H' (j omega) | so as to determine the amplitude-frequency response | H (j omega) | of the passive equalization circuit passive (jω)|。
The | Δ H (j ω) | represents the role of the blue filter in the visible light communication system based on the fluorescent LED. As shown in fig. 3, a passive equalization circuit for suppressing yellow light response based on a fixed-resistance bridge T-type network is schematically shown, and the transfer function H of the passive equalization circuit passive (s) can be expressed in terms of a second order pole-zero as follows:
wherein K a For the gain of the transfer function, K a Is a real number, z a1 And z a2 For zero point, p, corresponding to the transfer function a1 And p a2 Is the pole of the transfer function, z a1 、z a2 、p a1 And p a2 Is a plurality of numbers. The amplitude-frequency response corresponding to the passive equalization circuit is as follows:
|H passive (jω)|＝|H passive (s)| s＝jω (2)；
as shown in FIG. 3, the resistor R in the passive equalization circuit 0 Selecting a 50 ohm series resistor R as the load resistor a3 And R a4 All resistance values of (2) are equal to R 0 The circuit structure based on the fixed-resistance bridge T-type network has good high-frequency characteristic, and impedance balance branch Z in the T-type network is arranged 11 And Z 12 The amplitude-frequency response of the passive equalization circuit can be changed. In order to eliminate the influence of yellow light component by using the passive equalization circuit instead of the blue filter, the amplitude-frequency response | H (H) of the passive equalization circuit is determined according to the difference | Δ H (j ω) | passive (j ω) |; according to equation (2), the amplitude-frequency response | H of the passive equalization circuit passive (j ω) | is represented by the transfer function H of the passive equalization circuit passive (s) determining the transfer function of the passive equalization circuit from the gain K according to equation (1) a And zero point z a1 、z a2 And pole p a1 、p a2 The amplitude-frequency response | H of the passive equalization circuit can be changed by changing the corresponding zero pole and the gain of the passive equalization circuit passive (j ω) |; wherein the variation of | Δ H (j ω) | is concentrated at a low frequency, and when the frequency is greater than a certain value, | Δ H (j ω) | hardly varies with the frequency any more but approaches a constant, so | H (j ω) | is designed passive (j ω) | mainly attenuates | Δ H (j ω) | in a region where the variation of | Δ H (j ω) | is large at low frequencies, and | H | at high frequencies passive (j ω) | should be constant 1 in theory; gain K corresponding to the passive equalization circuit a And zero point z a1 、z a2 And pole p a1 、p a2 To obtain the theoretical amplitude-frequency response | H passive (j ω) |, according to the formula (1), the transfer function H corresponding to the passive equalization circuit at this time is obtained passive (s)。
The passive equalization circuit comprises an equalization branch Z 11 And Z 12 The impedance expression of (c) is:
according to the corresponding transfer function H of the passive equalization circuit passive (s) obtaining the balanced branch Z 11 And Z 12 The impedance expression of the passive equalization circuit is calculated by a filter comprehensive calculation method to obtain the element parameters of the equalization branch circuit contained in the passive equalization circuit. The equalization branch Z obtained by calculation in this disclosure 11 And Z 12 As shown in fig. 3, impedance equalizing branch Z 11 Comprising capacitors (C) arranged in parallel a1 ) Resistance (R) a2 ) And an inductor L connected in series a1 And a resistance R a1 Impedance balancing branch Z 12 One end of the resistor is connected to a resistor R connected in series a3 And R a4 Between the two ends, the other end is connected to ground, and an impedance balancing branch Z 12 Comprising an inductor L arranged in series a2 And a resistance R a5 And a capacitor (C) connected in parallel a2 ) Resistance (R) a6 )。
Operation S3: and an active equalization circuit is added, and the active equalization circuit is used for inhibiting the low-frequency signal of the input electric signal and amplifying the high-frequency signal, so that the bandwidth expansion of the fluorescent LED in the communication link is realized.
In the disclosed embodiment, operation S3 includes:
operation S31: measuring a third amplitude frequency response | H' (j omega) | of the LED after the passive equalization circuit is cascaded with the fluorescent LED;
operation S32: according to the third amplitude-frequency response | H '(j omega) |, and a target gain G given by the communication link, determining the amplitude-frequency response | H' of the active equalization circuit active (j ω) |; and
operation S33: according to amplitude-frequency response | H of the active equalization circuit active (j ω) |, configuring the active equalization circuit.
In the embodiment of the disclosure, the final passive equalization circuit and the active equalization circuit are required to be cascaded to jointly preprocess the input signal, so that the amplitude-frequency response | H ″ (j ω) | of the passive equalization circuit cascaded fluorescent LED needs to be measured before the active equalization circuit is designed. And cascading the passive equalization circuit obtained after the operation S2 with the high-power fluorescent LED, and scanning the amplitude characteristic of the visible light communication link at the moment through a network analyzer to obtain the amplitude-frequency response | H' (j omega) | of the fluorescent LED cascaded by the passive equalization circuit.
According to the embodiment of the present disclosure, as shown in fig. 4, an active equalization circuit having both functions of amplifying a high-frequency signal and suppressing a low-frequency signal is provided, and the active equalization circuit includes two equalization branches Z c And Z e And an NPN transistor Q b1 Wherein the first equalizing branch Z c Composed of a resistor and an inductor for suppressing low-frequency signals, and a second equalizing branch Z e The amplifier is composed of a resistor and a capacitor and is used for amplifying high-frequency signals. The active equalization circuit can be expressed by a second-order pole-zero form:
wherein K b Is the gain of the transfer function, K b Is a real number, z b1 And z b2 For zero point, p, corresponding to the transfer function b1 And p b2 For the pole of the transfer function, due to the equalizing branch Z of the active equalizing circuit c Comprising only inductance (L) b1 ) And resistance (R) b6 ) Component, equalizing branch Z e Comprising only capacitors (C) b1 ) And resistance (R) b5 ) Element, and thus pole-zero z, corresponding to the active equalization circuit b1 、z b2 、p b1 And p b2 Are real numbers. The corresponding amplitude-frequency response of the active equalization circuit is as follows:
|H active (jω)|＝|H active (s)| s＝jω (5)
resistor R in active equalization circuit b1 、R b2 、R b3 And R b4 For setting the transistor Q b1 So that the transistor operates in the linear amplification region, resistor R b1 、R b2 、R b3 And R b4 According to the transistorThe resistance R is obtained by calculating the static working point L Is a load, and a 50 ohm resistor R is selected b7 For impedance matching, a resistance of 20 ohms was chosen.
In operation S32, after obtaining the third amplitude-frequency response and the given target gain G, the amplitude-frequency response | H of the active equalization circuit is obtained by the following formula active (jω)|：
20log 10 (|H active (jω)|×|H″(jω)|)＝G (6)。
Under an ideal condition, the amplitude-frequency response of the high-power LED after passive equalization and active equalization is a constant, G is the integral gain of the visible light communication link based on the high-power LED after equalization, therefore, in order to determine the element parameters of the active equalization circuit, the integral gain G required by the visible light communication link is given out firstly, and G is selected to be 0dB in the implementation example of the invention; from equation (5), the amplitude-frequency response | H of the active equalization circuit active (j ω) | is determined by the transfer function H of the active equalization circuit active (s) determining the transfer function of the active equalization circuit from the gain K according to equation (4) b And zero point z b1 、z b2 And pole p b1 、p b2 The amplitude-frequency response | H of the active equalization circuit can be changed by changing the corresponding zero pole and gain of the active equalization circuit active (j ω) |; amplitude-frequency response | H according to active equalization circuit active (j ω) |, a pole-zero corresponding to the active equalization circuit is configured to obtain an element setting parameter of the active equalization circuit under the condition of meeting the given target gain G. According to the constraint condition in the formula (6), the pole-zero of the active equalization circuit is configured according to the amplitude-frequency response | H | (j ω) |, so that the amplitude-frequency response | H | of the active equalization circuit active The product of (j omega) and the amplitude-frequency response | H ″ (j omega) of the cascade fluorescence type LED of the passive equalization circuit is approximately constant 1, the gain G corresponding to the whole visible light communication link is 0dB at the moment, and the gain K of the active equalization circuit at the moment is obtained b And zero point z b1 、z b2 And pole p b1 、p b2 . The equalization branch element of the active equalization circuit shown in fig. 4 takes values satisfying the following expression:
gain K of the obtained active equalization circuit b And zero point z b1 、z b2 And pole p b1 、p b2 And substituting the equations (7a) - (7e) to obtain the element parameters of the two equalization branches in the active equalization circuit.
The present disclosure further provides a communication link constructed based on the bandwidth expansion method, as shown in fig. 5, the communication link includes:
the light source is a fluorescent LED;
the passive equalization circuit a is used for carrying out equalization processing on the input electric signal so as to inhibit the yellow light response of the fluorescent LED; and
and the active equalization circuit b is used for suppressing a low-frequency signal of the input electric signal and amplifying a high-frequency signal so as to realize bandwidth expansion of the fluorescent LED in the communication link.
In the embodiment of the disclosure, the passive equalization circuit is improved based on a fixed-resistance bridge T-type network. As shown in fig. 1 to 5, the passive equalization circuit a and the active equalization circuit b are cascaded through an impedance matching circuit; for driving a high-power fluorescent LED, after pre-equalization processing is performed on an input signal, the input signal is subjected to pre-equalization processingThe signal is applied to the LED by a commercially available driver module. In which the first equalizing branch Z in the active equalizing circuit c Composed of a resistor and an inductor for suppressing low-frequency signals of the input electrical signals, the equalizing branch Z c A collector connected to the NPN transistor; second equalizing branch Z in an active equalizing circuit e Composed of a resistor and a capacitor for amplifying high-frequency signals of input electric signals, and an equalizing branch Z e And the LED is connected to the emitter of the NPN transistor, then connected to the power amplifier PA, and then connected to the fluorescent LED, so that the bandwidth expansion of the fluorescent LED in the communication link is realized.
So far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It is to be noted that, in the attached drawings or in the description, the implementation modes not shown or described are all the modes known by the ordinary skilled person in the field of technology, and are not described in detail. Further, the above definitions of the various elements and methods are not limited to the various specific structures, shapes or arrangements of parts mentioned in the examples, which may be easily modified or substituted by those of ordinary skill in the art.
From the above description, those skilled in the art should clearly recognize that the communication link and the bandwidth expansion method of the fluorescent LED in the communication link of the present disclosure are applicable.
In summary, the present disclosure provides a communication link and a bandwidth expansion method for a fluorescent LED in the communication link, which do not need a blue filter, and can effectively solve the problems of attenuation of the blue filter to a high-frequency signal and limited equalization capability of the existing bandwidth expansion technology in the prior art.
It should also be noted that directional terms, such as "upper", "lower", "front", "rear", "left", "right", and the like, used in the embodiments are only directions referring to the drawings, and are not intended to limit the scope of the present disclosure. Throughout the drawings, like elements are represented by like or similar reference numerals. Conventional structures or constructions will be omitted when they may obscure the understanding of the present disclosure. And the shapes and sizes of the respective components in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure.
The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify a corresponding element does not by itself connote any ordinal number of the element or any ordering of one element from another or the order of manufacture, and the use of the ordinal numbers is only used to distinguish one element having a certain name from another element having a same name.
In addition, unless steps are specifically described or must occur in sequence, the order of the steps is not limited to that listed above and may be changed or rearranged as desired by the desired design. The embodiments described above may be mixed and matched with each other or with other embodiments based on design and reliability considerations, i.e., technical features in different embodiments may be freely combined to form further embodiments.
The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.
Claims (10)
1. A bandwidth expanding method of a fluorescent LED in a communication link comprises the following steps:
operation S1: constructing an original communication link based on a fluorescent LED light source;
operation S2: adding a passive equalization circuit in the original communication link, and performing equalization processing on an input electric signal through the passive equalization circuit to suppress yellow light response of the fluorescent LED; and
operation S3: and an active equalization circuit is added, and the active equalization circuit is used for inhibiting the low-frequency signal of the input electric signal and amplifying the high-frequency signal, so that the bandwidth expansion of the fluorescent LED in the communication link is realized.
2. The bandwidth expansion method of claim 1, wherein the operation S2 includes:
operation S21: determining amplitude-frequency response | H of passive equalization circuit passive (j ω) |; and
operation S22: according to amplitude-frequency response | H of the passive equalization circuit passive (j ω) | configures the passive equalization circuit.
3. The bandwidth expansion method of claim 2, wherein the operation S21 includes:
operation S211: measuring a first amplitude-frequency response | H (j ω) | of a fluorescent LED in an original communication link;
operation S212: measuring a second amplitude frequency response | H' (j ω) | in the case where a blue filter is used after the fluorescent LED; and
operation S213: obtaining an amplitude-frequency response difference value | delta H (j omega) | according to the first amplitude-frequency response | H (j omega) | and the second amplitude-frequency response | H' (j omega) | so as to determine the amplitude-frequency response | H (j omega) | of the passive equalization circuit passive (jω)|。
4. The bandwidth expansion method of claim 2, wherein in operation S22, the amplitude-frequency response | H of the passive equalization circuit is changed by changing the corresponding zero-pole and gain of the passive equalization circuit passive (jω)|。
5. The bandwidth expansion method of claim 1, wherein the operation S3 includes:
operation S31: measuring a third amplitude frequency response | H' (j omega) | of the LED after the passive equalization circuit is cascaded with the fluorescent LED;
operation S32: according to the third amplitude-frequency response | H '(j omega) |, and a target gain G given by the communication link, determining the amplitude-frequency response | H' of the active equalization circuit active (j ω) |; and
operation S33: according to amplitude-frequency response | H of the active equalization circuit active (j ω) |, configuring the active equalization circuit.
6. The belt of claim 5The wide spreading method, in operation S32, obtains a third amplitude-frequency response and a given target gain G, and then obtains an amplitude-frequency response | H of the active equalization circuit according to the following formula active (jω)|：
20log 10 (|H active (jω)|×|H″(jω)|)＝G。
7. The bandwidth extension method of claim 5, wherein in operation S33, the amplitude-frequency response | H of the active equalization circuit is determined according to active (j ω) |, a pole-zero corresponding to the active equalization circuit is configured to obtain an element setting parameter of the active equalization circuit under the condition of meeting the given target gain G.
8. A communication link, comprising:
the light source is a fluorescent LED;
the passive equalization circuit is used for performing equalization processing on the input electric signal so as to inhibit yellow light response of the fluorescent LED; and
and the active equalization circuit is used for suppressing a low-frequency signal of the input electric signal and amplifying a high-frequency signal so as to realize bandwidth expansion of the fluorescent LED in the communication link.
9. The communication link of claim 8, the passive equalization circuit being based on a fixed impedance bridge T-type network improvement.
10. The communication link of claim 8, the active equalization circuit comprising:
first equalizing branch Z c Consisting of a resistor and an inductor, for suppressing low-frequency signals of the input electrical signal, said equalizing branch Z c A collector connected to the NPN transistor; and
second equalizing branch Z e Composed of a resistor and a capacitor for amplifying high-frequency signals of input electrical signals, the equalizing branch Z e Is connected to the emitter of the NPN transistor.
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