TWI404353B - Optical network unit - Google Patents

Abstract

An optical network unit is disclosed, which comprises a signal receiving and generating unit for receiving an optical signal and generating an electrical signal correspondingly; a signal processing unit for processing the electrical signal; an inductor having one terminal being coupled to the ground; a first switch device. When a power supply normally supplies electricity to the optical network unit, the first switch device couples the signal receiving and generating unit to a power supply and to an input terminal of the signal processing unit, and when the power supply shuts down, the first switch device couples the signal receiving and generating unit to one end of the inductor different from the end connected to the ground, and disconnects the signal receiving and generating unit from the power supply.

Description

Light receiving module

The present invention relates to an optical receiving module in an optical fiber communication network, and more particularly to an optical receiving module capable of performing signal transmission when power is interrupted.

With the rapid development of the Internet, the requirements for bandwidth are getting higher and higher. In addition, cable TV services are becoming more diverse, and their bandwidth requirements are becoming higher and higher. Therefore, optical fiber communication networks have become the trend of developing broadband communications. For example, fiber-to-the-home or fiber-to-building fiber-to-point development is the goal of fiber-optic communication networks to gradually replace the original copper transmission.

In a fiber-optic communication network such as a cable television broadcasting system, a fiber-to-the-home (FTTH) network becomes the mainstream. In a fiber-to-the-home system, a central office converts a broadcast television signal into an optical signal, and transmits the optical signal to the optical cable. Then, the optical signal is reconverted into an electrical signal by the light receiving module, and finally the electrical signal is input to the video receiving device.

In the optical network, the Video Optical Unit is the main video receiving device. The light receiving module can provide rich video services under normal conditions (when there is power), but it will not operate if there is a power outage due to natural disasters such as earthquakes, hurricanes, floods, or power supply equipment failures. It is impossible to provide information transmission.

FIG. 1 shows a light receiving module 100 in accordance with an embodiment of the prior art. The light receiving module 100 includes a photodiode 102, a matching circuit 104, a plurality of amplifiers 106_1, 106_2, 106_3, and a subsequent stage circuit 110 composed of an automatic gain control circuit 108. When the power source (VCC) applies a reverse voltage to the photodiode 102 via the resistor (R), the photodiode 102 receives a certain intensity of the optical signal and converts it into an electrical signal of a corresponding intensity, the electrical signal including the radio frequency signal. The converted electrical signal is output to the subsequent stage circuit composed of the plurality of amplifiers 106 and the automatic gain control circuit 108 via the matching circuit 104. The matching circuit 104 can match the impedance of the photodiode 102 to the subsequent stage circuit to make the electrical signal. Can be processed by the latter circuit. The latter circuit performs amplification, gain control, filtering, etc. on the electrical signals output from the photodiode 102, and finally outputs.

However, when the external power supply is interrupted and no reverse voltage V _{CC is} applied to the photodiode 102, the circuit circuit for driving the photodiode 102 disappears, and the photodiode 102 is thus unable to generate a photoinduced current. In addition, all active components in the post-stage circuit lose their proper function due to the disappearance of the power supply. Therefore, in the case of power failure, according to the prior art, the light receiving module will lose the ability to transmit signals, so that the user cannot receive the information.

Therefore, there is a need for a novel light receiving module that can provide a rich video service in addition to normal (when there is power), even if it is powered off due to natural disasters such as earthquakes, hurricanes, floods, or power supply equipment failures. At this time, the operation can still be maintained to provide information transmission without power supply.

In view of the above, it is an object of the present invention to provide a light receiving module capable of transmitting information even when power is off.

According to an aspect of the present invention, a light receiving module is provided, comprising: a signal receiving and generating unit for receiving an optical signal and correspondingly generating an electrical signal, the electrical signal comprising a radio frequency signal; and a signal processing unit for processing the electrical signal The inductor is coupled to the ground at one end; the first switching device, when the power is supplied, couples the signal receiving and generating unit to the power source and the input end of the signal processing unit, and is disconnected from the inductor to enable the RF The signal is processed by the signal processing unit and output. When the power terminal is powered off, the output end of the signal receiving and generating unit is connected to the ungrounded end of the inductor and the signal receiving and generating unit is disconnected from the power source to enable signal reception and generation. The unit can still generate electrical signals and output RF signals.

According to still another aspect of the present invention, a light receiving module is provided, comprising: a signal receiving and generating unit, comprising: a photodiode for receiving an optical signal to correspondingly generate an electrical signal including a radio frequency signal, and a matching circuit The impedance of the photodiode is matched with the external impedance connected to the signal receiving and generating unit; the signal processing unit is for processing the electrical signal; the inductor is coupled to the ground at one end; and the first switching device is when the power supply is normally supplied. The signal receiving and generating unit is coupled to the power source, and when the power source is powered off, the cathode of the photodiode is coupled to the ground so that the signal receiving and generating unit can still generate the electrical signal; the second switching device, When the power supply is provided, the signal receiving and generating unit is coupled to the input end of the signal processing unit, and is disconnected from the inductor, so that the RF signal is processed by the signal processing unit and output, and when the power terminal is powered off, the signal is received. And the generating unit is connected to the ungrounded end of the inductor to output the RF signal.

According to an embodiment of the invention, the signal processing unit comprises an amplifier and an automatic gain control circuit. The power supply includes a DC voltage source and a resistor connected in series with the DC voltage source.

According to an embodiment of the present invention, the light receiving module may have a second switching device and an output port for outputting the RF signal, and when the power terminal is powered, the output end of the signal processing unit is connected to the output port, and When the power supply is powered off, connect the ungrounded end of the inductor to the output port.

According to an embodiment of the invention, the two separate RF signal outputs are respectively connected to the output end of the signal processing unit and the ungrounded end of the inductor.

According to the light receiving module of the present invention, in the case of no power, the current loop required for the operation can be maintained to output the radio frequency signal, so that normal audio and video transmission can be provided when the power is available, and the service can still be broadcasted when the power is turned off. . As well as the visual design requirements, the RF signals are output from the same output 有 when they are powered or not, or are output from different outputs 分别.

In the following description, embodiments according to the present invention will be described with reference to the accompanying drawings. The details of one or more embodiments of the invention are disclosed in the drawings and the description below. The above and other features, objects, and advantages of the invention will be apparent from the description and appended claims.

In the various figures, the same or similar elements are denoted by the same reference numerals, and the description is omitted for the sake of brevity.

According to the present invention, in the case of power-off, the photodiode can still maintain the operating current loop and the radio frequency (RF) signal correspondingly generated by the photodiode due to the received optical signal can be output.

2 is a block diagram showing a light receiving module 200 in accordance with an embodiment of the present invention. As shown in FIG. 2, the light receiving module 200 includes a photodiode 202, a first inductor L ₀ , a matching device 204 , a first switching device SW1 , a post processing circuit 206 , a second inductor L ₁ , and a second switching Device SW2. The photodiode 202 receives the optical signal emitted by the corresponding laser diode (not shown) to generate a corresponding electrical signal. In general, during normal operation, the electrical signal output by photodiode 202 includes a direct current signal and a radio frequency (RF) signal. The matching device 204 matches the impedance of the photodiode 202 with the impedance of the subsequent post-stage circuit to output the radio frequency signal. The first inductance L ₀ allows the direct current signal to pass but blocks the radio frequency signal because the first inductance L ₀ is an infinite equivalent impedance for the radio frequency signal. Photodiode 202, the inductance L ₀ and the first matching device 204 is formed integrally signal reception and generation units. The post-processing circuit 206 functions as a signal processing unit of the light receiving module for processing the electrical signals output via the matching device 204. As described in the prior art section, the post-processing circuit 206 can include an amplifier, an automatic gain control circuit, and the like.

In the light receiving module 200, the anode of the photodiode 202 is grounded and the cathode is coupled to the matching circuit 204 via the capacitor C1. The other end of the matching circuit 204 is coupled to the common terminal of the first switching device SW1 via a capacitor C2. One end of the first inductor L ₀ is also connected to the common terminal, and the other end is connected to the anode of the photodiode 202.

Thus, in the case of the normal power supply, the first switching means SW1 is switched to connect the resistor R and L _0, and thus the power supply VCC is connected to the photo diode 202 reverse biased. At this time, when the photodiode receives the optical signal, it converts it into an electrical signal containing the radio frequency signal. As described above, the generated radio frequency signal does not flow through the first inductor L ₀ but is output to the post-stage circuit 206 via the matching circuit 204. Then, the post-processing circuit 206 amplifies the input radio frequency signal, performs filtering, and the like, and transmits it to the output port via the second switching device SW2, and inputs it to an external device (not shown) such as an audio-visual device. The second switching means SW2 output terminal based radio frequency (RF) output port connected to the rear stage circuit 206 in the normal power supply line connected to the RF output port to the end of L ₁ at power-off.

In the case of the power interruption, shown in Figure 2, the switching device SW1 as shown as a dotted arrow, the second inductor is connected to one end of a first inductor L ₁ L _0, not connected to the resistance R. Thus, by switching the first switch SW1, photodiode cathode 202 via a first series inductor and the second inductor L ₀ L _1, and finally connected to ground to form a loop. At this time, the direct current is grounded by the photodiode 202 flowing through the first and second inductors L ₀ and L ₁ (short for the direct current signal), and the resistor R is disconnected from the photodiode 202 without The electrical signal generated by the photodiode 202 due to the reception of the optical signal is affected by its high resistance. In this way, the RF signal converted by the photodiode 202 is sequentially output to the RF output port via the matching circuit 204, the first switching device SW1, and the second switch SW2. At this time, since the second inductor L ₁ blocks the radio frequency signal from flowing to the grounded end, the radio frequency signal can be directly transmitted from the first switch SW1 to the second switching device SW2. It is worth noting that, in the absence of power, the second inductor L ₁ is short-circuited to the DC signal in the electrical signal generated by the photodiode 202 due to the reception of the optical signal, but is open to the radio frequency (RF) signal in the electrical signal. Therefore, the DC signal generated by the photodiode 202 can form an effective circuit loop, and the RF signal does not flow to the ground and can be output from the RF output. In other words, if not through the second inductor L ₁ is grounded, when no DC power circuit 202 of the photodiode body in an open state so that no RF signal output, a second inductor L ₁ if not directly grounded, the RF signals may It flows into the ground and cannot be output from the RF output.

In addition, since the first switching device SW1 and the second switching device SW2 are switched to be directly connected to be disconnected from the resistor R of the power supply terminal when there is no power, the RF signal is not affected by the high resistance of the resistor R to attenuate the intensity.

Thus, according to this embodiment, in the case of no electricity, since the switching means SW1 and SW2 and cooperating inductance of L _1, photodiode 202 to maintain the desired operation of the loop current without breaking passage remains, and The strength of the RF signal is not attenuated by the high resistance of the power supply. At the same time, the RF signal can be output through the output 有 when the power is on, that is, according to the present embodiment, when there is no power and when there is power, the RF signal is output from the same RF output 埠. In this way, normal audio and video transmission can be provided when there is power, and the service can still be broadcasted when the power is off.

FIG. 3 is a block diagram showing a light receiving module 300 in accordance with another embodiment of the present invention.

The light receiving module shown in FIG. 3 is mainly different from the light receiving module shown in FIG. 2 in that only the first switching device SW1 is provided and the second switching device SW2 is not provided, and the second RF output is added. . The same or similar portions in Fig. 3 as those in Fig. 2 are denoted by the same reference numerals, and the description thereof will be omitted.

The light receiving module 300 is only provided with the first switching device SW1 to switch to the inductor L ₁ when the power is off, and to set the second RF output port to output the radio frequency signal via the buffer when the power is off. Thus, when there is power, the RF signal is output via the first RF output, and when there is no power, it is output via the second RF output.

In addition, since the first switch SW1 is switched to be disconnected from the resistor R of the power supply terminal when the power is off, and the radio frequency signal is directly outputted from the second RF output port, the radio frequency signal is not affected by the high resistance of the resistor R to attenuate the intensity.

Thus, according to this embodiment, in the case of no electricity, since the switching device SW1 and the inductance of L ₁ coordinated operation, photodiode 202 to maintain the desired operation of the current loop path remains without breaking, and the radio frequency signal The strength does not decay due to the high resistance of the power supply. In this way, normal audio and video transmission can be provided when there is power, and the service can still be broadcasted when the power is off.

4 is a block diagram showing a light receiving module 400 in accordance with still another embodiment of the present invention.

The light receiving module 400 shown in FIG. 4 is mainly different from the light receiving module 200 shown in FIG. 2 in that a third switching device SW3 is additionally provided between the power supply terminal V _CC and the photodiode 202. The same or similar portions in Fig. 4 as those in Fig. 2 are denoted by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 4, the third switching device SW3 is disposed between the cathode of the photodiode 202 and the resistor R. At the time of normal power supply, the third switching device SW3 causes the photodiode 202 to receive the reverse bias of the power supply voltage Vcc. In this case, the output path of the radio frequency signal of the electric signal correspondingly generated when the photodiode 202 receives the optical signal is the same as that described above with reference to FIG. The RF signal is output to the RF output port via the matching circuit 204, the first switch SW1, the post-processing circuit 206, and the second switching device SW2.

When the power is interrupted, the third switching device SW3 is disconnected from the power supply voltage V _CC and connected to the ground so that the photodiode 202 can maintain the conduction loop of the direct current signal when the power is turned off. The operation of the first and second switching devices SW1 and SW2 and the output path of the radio frequency signal are the same as those described above with reference to the description of FIG. 2, and details are not described herein again.

Thus, according to this embodiment, in the case of no electricity, since the switching means SW1, SW2 and SW3, and cooperating inductance of L _1, photodiode 202 to maintain the desired operation of the current loop path remains without breaking And the strength of the RF signal is not attenuated by the high resistance of the power supply terminal. At the same time, the RF signal can be output through the output 有 when the power is on, that is, according to the present embodiment, when there is no power and when there is power, the RF signal is output from the same RF output 埠. In this way, normal audio and video transmission can be provided when there is power, and the service can still be broadcasted when the power is off.

FIG. 5 is a block diagram showing a light receiving module 500 in accordance with another embodiment of the present invention.

The light receiving module shown in FIG. 5 is mainly different from the light receiving module shown in FIG. 4 in that the second switching device SW1 is not provided and the second RF output port is set. The same or similar portions in FIG. 5 as those in FIG. 4 are denoted by the same reference numerals, and the description thereof will be omitted.

The light receiving module 500 is not provided with the second switching device SW2, but sets the first RF output port as the output port of the RF signal during normal power supply, and sets the second RF output port as the output port of the RF signal when the power is interrupted. Thus, when there is power, the RF signal is output via the first RF output, and when there is no power, it is output via the second RF output.

Thus, according to this embodiment, in the case of no electricity, since switching devices SW1 and SW3, and cooperating inductance of L _1, photodiode 202 to maintain the desired operation of the loop current without breaking passage remains, and The strength of the RF signal is not attenuated by the high resistance of the power supply. In this way, normal audio and video transmission can be provided when there is power, and the service can still be broadcasted when the power is off.

While the preferred embodiment of the present invention has been described in the foregoing specification, the foregoing description is intended to be illustrative only There are many modifications and substitutions that can be made without departing from the scope and spirit of the invention.

200. . . Light receiving module

202. . . Photodiode

204. . . Matching circuit

206. . . Rear stage circuit

300. . . Light receiving module

400. . . Light receiving module

500. . . Light receiving module

L ₀ . . . First inductance

L ₁ . . . Second inductance

SW1. . . First switch

SW2. . . Second switch

SW3. . . Third switch

Figure 1 shows a prior art light receiving module.

2 is a block diagram showing a light receiving module in accordance with an embodiment of the present invention.

3 is a block diagram showing a light receiving module according to another embodiment of the present invention.

4 is a block diagram showing a light receiving module according to still another embodiment of the present invention.

Figure 5 is a block diagram showing a light receiving module according to still another embodiment of the present invention.

200. . . Light receiving module

202. . . Photodiode

204. . . Matching circuit

206. . . Rear stage circuit

L ₀ . . . First inductance

L ₁ . . . Second inductance

SW1. . . First switch

SW2. . . Second switch

Claims (11)

An optical receiving module includes: a signal receiving and generating unit for receiving an optical signal and correspondingly generating an electrical signal, the electrical signal comprising a radio frequency signal; a signal processing unit for processing the electrical signal; and an inductor coupled to one end to The first switching device is configured to couple the signal receiving and generating unit to the power source and to the input end of the signal processing unit when the power source is powered, and disconnected from the inductor to pass the RF signal. The signal processing unit processes the output, and when the power terminal is powered off, the output end of the signal receiving and generating unit is connected to the ungrounded end of the inductor and the signal receiving and generating unit is disconnected from the power source, so that The signal receiving and generating unit can still generate the electrical signal and output the radio frequency signal. The optical receiving module of claim 1, wherein the signal receiving and generating unit comprises: a photodiode for receiving an optical signal to correspondingly generate the electrical signal; and a matching circuit for making the photodiode The impedance of the body matches the external impedance connected to the signal receiving and generating unit. The optical receiving module of claim 1, wherein the signal processing unit comprises an amplifier and an automatic gain control circuit. The light receiving module of claim 1, wherein the power source comprises a DC voltage source and a resistor connected in series with the DC voltage source. For example, the optical receiving module of claim 1 further includes a second switching device and an output port for outputting the radio frequency signal, and when the power terminal is powered, the output end of the signal processing unit is connected to the output port. And when the power terminal is powered off, the ungrounded end of the inductor is connected to the output port. For example, the optical receiving module of claim 1 includes two separate RF signal output ports respectively connected to the output end of the signal processing unit and the ungrounded end of the inductor. An optical receiving module includes: a signal receiving and generating unit, comprising: a photodiode for receiving an optical signal to correspondingly generate an electrical signal including a radio frequency signal, and a matching circuit to make the impedance of the photodiode The external impedance connected to the signal receiving and generating unit is matched; the signal processing unit is configured to process the electrical signal; the inductor is coupled to the ground at one end; and the first switching device enables the signal to be received when the power supply is normally powered. The generating unit is coupled to the power source, and when the power source is powered off, the cathode of the photodiode is coupled to the ground, so that the signal receiving and generating unit can still generate the electrical signal; the second switching device, when When the power is supplied, the signal receiving and generating unit is coupled to the input end of the signal processing unit, and is disconnected from the inductor, so that the RF signal is processed by the signal processing unit and outputted when the power terminal is powered off. The signal receiving and generating unit is connected to an ungrounded end of the inductor to output the radio frequency signal. The optical receiving module of claim 7, wherein the signal processing unit comprises an amplifier and an automatic gain control circuit. The light receiving module of claim 7, wherein the power source comprises a DC voltage source and a resistor connected in series with the DC voltage source. For example, the optical receiving module of claim 7 further includes an output port for outputting the radio frequency signal, and when the power terminal is powered, the output end of the signal processing unit is connected to the output port, and when When the power terminal is powered off, the ungrounded end of the inductor is connected to the output port. For example, the optical receiving module of claim 7 includes two separate RF signal output ports respectively connected to the output end of the signal processing unit and the ungrounded end of the inductor.