Implementation circuit, method and receiver of multi-coupling structure based on signal transmission

Abstract

The present application provides a circuit, method and receiver for realizing a multi-coupling structure based on signal transmission, wherein the circuit comprises: a differential signal input module, comprising a first receiving input terminal and a second receiving input terminal, wherein the differential value between the first receiving input terminal and the second receiving input terminal is used as the signal value input by the differential signal input module; a coupling mode switching module, which switches between a DC coupling function and an AC coupling function by turning on and off different switches according to the transmission state of the signal value; an analog front end, which applies a DC bias voltage to the output voltage of the coupling mode switching module; the coupling mode switching module comprises a coupling capacitor, wherein the coupling capacitor forms a path corresponding to the DC coupling function or the AC coupling function by turning on and off different switches. The present application can simultaneously meet the requirements of using different coupling methods for signal transmission in different modes.

Description

Technical Field

[0001] The present application belongs to the technical field of signal transmission, and relates to an implementation circuit, and in particular to an implementation circuit, method and receiver based on a multi-coupling structure of signal transmission. Background Art

[0002] In signal transmission, especially high-speed signal transmission, according to the signal coupling method, it is mainly divided into DC coupling (DC coupling) and AC coupling (Ac coupling). DC coupling refers to directly transmitting the signal to the receiving end without isolation through capacitors, and the DC component in the signal will be directly transmitted to the receiving end. DC coupling is widely used in situations where the DC component of the signal needs to be retained, such as power signal transmission, low-frequency signal transmission, and high-speed digital circuits that need to accurately transmit voltage levels. Its advantage is that there is no frequency restriction, and DC and low-frequency signals can be transmitted without attenuation. AC coupling refers to transmitting the AC component of the signal to the receiving end through a capacitor, while the DC component is blocked by the capacitor. It is often used to remove the DC bias in the signal. AC coupling is widely used in signal transmission between different modules or chips, such as in Serdes links in optical fiber communication. Its advantage is DC isolation, which can eliminate DC offset in the signal and avoid DC offset problems. At the same time, it can isolate noise between different power domains and reduce interference.

[0003] However, both DC coupling and AC coupling have certain disadvantages. The disadvantage of DC coupling is the DC offset problem, which may introduce DC offset voltage, causing signal deviation. At the same time, the power consumption is high, and more power is usually required to maintain signal transmission. The disadvantage of AC coupling is that there is a frequency limit, and low-frequency signals will be attenuated by capacitors, which is not suitable for low-frequency applications. Summary of the invention

[0004] The present application provides a circuit, method and receiver for realizing a multi-coupling structure based on signal transmission, which are used to solve the problem of how to simultaneously meet the requirements of using different coupling methods for signal transmission in different modes.

[0005] In the first aspect, the present application provides an implementation circuit of a multi-coupling structure based on signal transmission, the circuit comprising: a differential signal input module, comprising a first receiving input terminal and a second receiving input terminal, configured to use the differential value of the first receiving input terminal and the second receiving input terminal as the signal value input by the differential signal input module; a coupling mode switching module, configured to switch between a DC coupling function and an AC coupling function by turning on and off different switches according to the transmission state of the signal value; an analog front end, configured to apply a DC bias voltage to the output voltage of the coupling mode switching module; the coupling mode switching module comprises a coupling capacitor, and the coupling capacitor forms a path corresponding to the DC coupling function or the AC coupling function by turning on and off different switches, and the output voltage of the coupling capacitor serves as the output voltage of the coupling mode switching module.

[0006] In an implementation manner of the first aspect, the coupling mode switching module further includes: a zeroth switch, a first switch, a second switch, and a third switch; the zeroth switch and the first switch are turned on, the second switch and the third switch are turned off, the coupling capacitor forms a DC path, and the coupling mode switching module switches to a DC coupling function; the zeroth switch and the first switch are turned off, the second switch and the third switch are turned on, the coupling capacitor forms an AC path, and the coupling mode switching module switches to an AC coupling function.

[0007] In an implementation of the first aspect, in response to the coupling mode switching module switching to a DC coupling function, a bias matching circuit outside the circuit is used to apply a DC bias voltage to the output voltage of the coupling mode switching module; in response to the coupling mode switching module switching to an AC coupling function, a bias matching circuit inside the circuit is used to apply a DC bias voltage to the output voltage of the coupling mode switching module.

[0008] In an implementation of the first aspect, the coupling mode switching module also includes: a zeroth switching switch, a first switching switch, a second switching switch, a third switching switch, a fourth switching switch, a fifth switching switch and a sixth switching switch; in response to the transmission state of the signal value being in a data packet gap state, the zeroth switching switch and the first switching switch are disconnected, and the second switching switch and the third switching switch are turned on, and the common mode voltage of the first receiving input terminal and the second receiving input terminal is transmitted to the coupling capacitor input terminal, and the output voltage of the coupling capacitor is connected to a DC bias voltage through the turned-on fifth switching switch and the sixth switching switch.

[0009] In an implementation manner of the first aspect, in response to the transmission state of the signal value being in a data packet gap state, the fourth switch is turned on, further ensuring that the output voltage of the coupling mode switching module is equal to the DC bias voltage.

[0010] In an implementation of the first aspect, the coupling mode switching module also includes: a bias resistor; in response to the transmission state of the signal value being in a normal data transmission state, the zeroth switching switch and the first switching switch are turned on, the second switching switch and the third switching switch are turned off, the fourth switching switch, the fifth switching switch and the sixth switching switch are turned off, and the common mode voltage of the first receiving input terminal and the second receiving input terminal is transmitted to the coupling capacitor input terminal, and the output voltage of the coupling capacitor is connected to the DC bias voltage through the bias resistor.

[0011] In an implementation of the first aspect, the coupling capacitor includes a first coupling capacitor and a second coupling capacitor; in response to the transmission state of the signal value being in a normal data transmission state, an average value or a DC value of the first coupling capacitor and the second coupling capacitor is determined by a common mode voltage and an internal bias voltage of the first receiving input terminal and the second receiving input terminal.

[0012] In the second aspect, the present application provides a method for implementing a multi-coupling structure based on signal transmission, which is applied to an implementation circuit of a multi-coupling structure based on signal transmission, wherein the circuit includes a differential signal input module, a coupling mode switching module and an analog front end, wherein the differential signal input module includes a first receiving input terminal and a second receiving input terminal, and the coupling mode switching module includes a coupling capacitor; the method includes: taking the differential value of the first receiving input terminal and the second receiving input terminal as the signal value input by the differential signal input module; according to the transmission state of the signal value, the coupling capacitor forms a path corresponding to the DC coupling function or the AC coupling function by turning on and off different switches, so as to realize switching between the DC coupling function and the AC coupling function; applying a DC bias voltage to the output voltage of the coupling mode switching module.

[0013] In a third aspect, the present application provides a receiver, comprising: the circuit described above.

[0014] In an implementation of the third aspect, the receiver includes an optical module receiver; the optical module receiver is arranged in an optical fiber serial communication circuit, the optical fiber serial communication circuit is connected to an optical cable terminal, and the optical cable terminal is connected to multiple optical network units; multiple optical network units share the same physical link in a time division multiplexing manner; each of the optical network units sends a short data packet, and the optical cable terminal receives the short data packets sent by each optical network unit in an intermittent mode, and transmits the processed data packets as signal values ​​to the differential signal input module of the optical module receiver.

[0015] In an implementation of the third aspect, a data valid signal sent by an optical module transmitter indicates a correct configuration mode of the optical fiber serial communication circuit, and the correct configuration mode includes controlling the time when different switches are turned on and off.

[0016] As described above, the implementation circuit, method and receiver of the multi-coupling structure based on signal transmission described in the present application have the following beneficial effects:

[0017] The present application can support the requirements of DC coupling and AC coupling at the receiving end at the same time. Under the conditions of meeting the requirements of signal integrity, internal bias of the circuit, etc., it can effectively solve the problems of coupling capacitor charging and discharging caused by conventional AC coupling in the burst mode, as well as the abnormal signal level at the beginning of data transmission. The circuit solution provided by the present application does not need to extend the preamble time at the beginning of data transmission, thereby increasing more effective data transmission time for the system, increasing the effective bandwidth of the system, and also improving the network speed of users using network communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Shown is a circuit structure schematic diagram of the implementation circuit described in the embodiment of the present application.

[0019] Figure 2 A DC coupling schematic diagram showing a first circuit structure of an implementation circuit described in an embodiment of the present application is shown.

[0020] Figure 3 A schematic diagram showing an AC coupling of a first circuit structure of an implementation circuit according to an embodiment of the present application is shown.

[0021] Figure 4 A DC coupling schematic diagram showing a second circuit structure of an implementation circuit described in an embodiment of the present application is shown.

[0022] Figure 5 An AC coupling schematic diagram showing a second circuit structure of an implementation circuit described in an embodiment of the present application is shown.

[0023] Figure 6Shown is a schematic diagram of capacitor charging and discharging of an implementation circuit described in an embodiment of the present application.

[0024] Figure 7 Shown is a principle flow chart of the implementation method described in the embodiment of the present application.

[0025] Figure 8 Shown is a schematic diagram of the structural principle of the receiver described in an embodiment of the present application.

[0026] Fig. 9 Shown is an application circuit structure diagram of the receiver described in an embodiment of the present application.

[0027] Fig.10 Shown is a data transmission and reception waveform diagram of the receiver described in an embodiment of the present application.

[0028] Component number description

[0029] 1 Implementation circuit of multi-coupling structure based on signal transmission

[0030] 11 Differential signal input module

[0031] 12 Coupling mode switching module

[0032] 13 Analog Front End

[0033] Steps S71 to S73 DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0035] It should be noted that the illustrations provided in the following embodiments are only used to illustrate the basic concept of the present application in a schematic manner, and therefore the illustrations only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0036] In the current high-speed communication protocols, most of them use AC coupling, mainly to provide electrical isolation, eliminate DC offset, improve signal integrity and adapt to different interface specifications. These advantages make AC coupling a more ideal choice in high-speed data communication and complex electronic systems. In addition, in the chip implementation, in the AC mode, the AC coupling capacitor can be integrated into the chip. In addition to effectively reducing the number of external components and reducing costs, the on-chip coupling capacitor can also provide additional help for the ESD (Electro-Static discharge) inside the chip, effectively improving the reliability of the chip, but it cannot meet the needs of supporting both DC coupling and AC coupling at the receiving end.

[0037] The technical solutions in the embodiments of the present application will be described in detail below in conjunction with the drawings in the embodiments of the present application.

[0038] See also Figure 1 , which is a schematic diagram of the circuit structure of the implementation circuit described in the embodiment of the present application. Figure 1 As shown, an embodiment of the present application provides an implementation circuit 1 of a multi-coupling structure based on signal transmission, specifically comprising: a differential signal input module 11, a coupling mode switching module 12 and an analog front end 13.

[0039] The differential signal input module 11 comprises a first receiving input terminal and a second receiving input terminal, and is configured to use the differential value between the first receiving input terminal and the second receiving input terminal as the signal value input by the differential signal input module 11;

[0040] The coupling mode switching module 12 is configured to switch between a DC coupling function and an AC coupling function by turning on and off different switches according to the transmission state of the signal value.

[0041] The analog front end 13 is configured to apply a DC bias voltage to the output voltage of the coupling mode switching module 12 .

[0042] The coupling mode switching module 12 includes a coupling capacitor. The coupling capacitor forms a path corresponding to a DC coupling function or an AC coupling function by turning on and off different switches. The output voltage of the coupling capacitor serves as the output voltage of the coupling mode switching module 12 .

[0043] The output voltage of the coupling mode switching module 12 contains the information of the received data in the working mode, which will be amplified and sampled by the analog front end 13, and then sent to the subsequent digital circuit part for further processing to parse the correct data. The DC bias voltage means that the analog front end needs to work normally within a certain working voltage range, and the role of the bias voltage is to apply this working voltage to the analog front end.

[0044] See also Figure 2 , which is a DC coupling schematic diagram of the first circuit structure of the implementation circuit described in the embodiment of the present application. Figure 2 As shown, the coupling mode switching module 12 includes, in addition to the coupling capacitor Cac, a zeroth switch sw0, a first switch sw1, a second switch sw2 and a third switch sw3. Different coupling modes will be controlled by different switches. In practical applications, in order to reduce the influence of parasitic effects on the bandwidth of the signal path, the switch under each path (DC path or AC path) needs to be optimized according to the supported mode and rate.

[0045] Figure 2 In the embodiment shown, a selector (mux) is used at the front end of the circuit to select different coupling modes. Since most high-speed signals use differential mode to transmit signals, the input ends are represented by RXP and RXN, namely the first receiving input end RXP and the second receiving input end RXN. The actual signal value is represented by the differential value of RXP and RXN: (RXP-RXN). For the application of optical module communication, there is usually a certain DC bias at the transmitting end of the optical module transceiver, so RXP and RXN also have a common mode value Vcm. Vcm=(RXP+RXN) / 2. Taking a common optical module transmission signal as an example, the high level of RXP and RXN is 2.4V and the low level is 1.6V, so when RXP=2.4V, RXN=1.6V, and RXP-RXN=0.8V, it means that the data sent by the optical module to the serdes circuit is 1, and when RXP=1.6V and RX N=2.4V, RXP–RXN=-0.8V, it means that the data sent by the optical module to the serdes circuit is 0. Regardless of whether 1 or 0 is sent, the common mode voltage of RXP and RXN (VCM = (RXP + RXN) / 2) is always 2V.

[0046] like Figure 2 As shown, the zeroth switch sw0 and the first switch sw1 are turned on, the second switch sw2 and the third switch sw3 are turned off, the coupling capacitor Cac forms a DC path, and the coupling mode switching module is switched to a DC coupling function.

[0047] See also Figure 3 , which is a schematic diagram of AC coupling of a first circuit structure of an implementation circuit according to an embodiment of the present application. Figure 3 As shown, the zeroth switch sw0 and the first switch sw1 are disconnected, the second switch sw2 and the third switch sw3 are turned on, the coupling capacitor Cac forms an AC path, and the coupling mode switching module is switched to an AC coupling function.

[0048] In one embodiment, in response to the coupling mode switching module switching to the DC coupling function, a bias matching circuit outside the circuit is used to apply a DC bias voltage to the output voltage of the coupling mode switching module; in response to the coupling mode switching module switching to the AC coupling function, a bias matching circuit inside the circuit is used to apply a DC bias voltage to the output voltage of the coupling mode switching module.

[0049] In practical applications, the external circuit refers to other power management chips outside the chip where the implementation circuit is located, which are produced by some passive components, such as resistors and capacitors on the board. The internal circuit refers to the inside of the chip where the implementation circuit itself is located, which is produced by the power management module inside the chip.

[0050] like Figure 2 As shown, in DC coupling mode, the zeroth switch sw0 and the first switch sw1 of the DC path will be turned on, while the second switch sw2 and the third switch sw3 of the AC path will be turned off. At this time, RXP is directly connected to VGP, and RXN is directly connected to VGN. If the common-mode DC voltage (2V) of RXP and RXN is too high for the internal analog front-end circuit, a bias matching circuit outside the chip can be used to help provide appropriate VGP and VGN DC bias voltages.

[0051] like Figure 3 As shown, in the AC coupling mode, the zeroth switch sw0 and the first switch sw1 of the DC path will be disconnected (off), and the second switch sw2 and the third switch sw3 of the AC path will be turned on (on). At this time, the bias of the circuit (the DC voltage value at VGP / VGN) is provided by the circuit inside the chip.

[0052] See also Figure 4 , which is a DC coupling schematic diagram of the second circuit structure of the implementation circuit described in the embodiment of the present application. Figure 4 As shown, the coupling mode switching module 12 includes, in addition to the coupling capacitor Cac, a zeroth switch sw0, a first switch sw1, a second switch sw2, a third switch sw3, a fourth switch sw4, a fifth switch sw5 and a sixth switch sw6.

[0053] like Figure 4 As shown, in response to the transmission state of the signal value being in the data packet gap state, the zeroth switching switch sw0 and the first switching switch sw1 are disconnected, the second switching switch sw2 and the third switching switch sw3 are turned on, and the common mode voltage of the first receiving input terminal and the second receiving input terminal is transmitted to the coupling capacitor input terminal, and the output voltage of the coupling capacitor is connected to the DC bias voltage through the turned-on fifth switching switch sw5 and the sixth switching switch sw6.

[0054] Furthermore, in response to the transmission state of the signal value being in a data packet gap state, the fourth switch sw4 is turned on, further ensuring that the output voltage of the coupling mode switching module is equal to the DC bias voltage.

[0055] like Figure 4 As shown, a “quasi-DC coupling” mode is used to implement a function similar to DC coupling to solve the data loss caused by the charging and discharging of the AC coupling capacitor when receiving burst mode data during AC coupling.

[0056] Specifically, regarding "quasi-DC coupling", when receiving burst mode data, the received data is divided into two possible states. Figure 4 As shown in the figure, the state of the circuit during the packet gap (guard time), the duration of the guard time is specified by the protocol. During the guard time period, the optical transceiver will output a fixed signal level (such as RXP = 2.4V, RXN = 1.6V or RXP = 1.6V, RXN = 2.4V). The Rcm resistor will obtain the common mode voltage VCM of RXP and RXN (VCM = (RXP + RXN) / 2, for the above RXP / RXN is 2.4V and 1.6V, Vcm = 2V), and add this common mode voltage to the input ports VA and VB of the two coupling capacitors Cac through the turned-on switches sw2 and sw3. At this time, sw0 and sw1 are in the disconnected state, so VA = VB = VCM. The voltage VGP and VGN of the other port of the coupling capacitor Cac are connected to the vbias generated by the internal bias circuit through the turned-on switches sw5 and sw6. In some implementations, sw4 can be turned on to further ensure that VGP = VGN = vbias. Through the above implementation principle, the DC voltages of the two ports of the coupling capacitor Cac can also be kept consistent with the data transmission mode during the guard time.

[0057] See also Figure 5 , which is a schematic diagram of AC coupling of a second circuit structure of the implementation circuit described in an embodiment of the present application. Figure 5 As shown, the coupling mode switching module 12 further includes: a bias resistor Rbias.

[0058] In response to the transmission state of the signal value being in a normal data transmission state, the zeroth switching switch sw0 and the first switching switch sw1 are turned on, the second switching switch sw2 and the third switching switch sw3 are turned off, the fourth switching switch sw4, the fifth switching switch sw5 and the sixth switching switch sw6 are turned off, and the common mode voltage of the first receiving input terminal and the second receiving input terminal is transmitted to the input terminal of the coupling capacitor Cac, and the output voltage of the coupling capacitor Cac is connected to the DC bias voltage through the bias resistor.

[0059] like Figure 5 As shown in the figure, during the data transmission, the optical transceiver will output user data. Therefore, RXP and RXN will switch between high and low levels (high level = 2.4V, low level = 1.6V) at high speed according to the specific data. During data transmission, sw2 and sw3 will be disconnected, while sw0 and sw1 will be turned on. Therefore, VA = RXP, VB = RXN. Since RXP and RXN are constantly switching between high and low levels, as shown in the figure, Figure 6 As shown in the figure, v / vin refers to the voltage of the transmission signal, Vdiff refers to the voltage of the input differential signal (RXP, RXN), Vcap_p refers to the coupling capacitor at the P end, and Vcap_n refers to the coupling capacitor at the N end, so the average value of VA and VB is approximately equal to the common mode voltage value of RXP or RXN (VCM=(2.4+1.6) / 2=2V). The other end of the coupling capacitor Cac (VGP or VGN) is connected to the vbias generated by the internal bias circuit through Rbias, ensuring that the input DC bias voltage value of the analog front end is the expected design value.

[0060] Figure 5 At this time, sw4, sw5, and sw6 are all disconnected, which ensures that the jump AC signal of RXP and RXN can be correctly added to VGP and VGN. Then it is further amplified and processed by the analog front-end circuit. Figure 5 If only AC coupling is needed, sw0 and sw1 need to be turned on, while sw2, sw3, sw4, sw5 and sw6 are always turned off.

[0061] In one embodiment, the coupling capacitor includes a first coupling capacitor and a second coupling capacitor.

[0062] In response to the transmission state of the signal value being in a normal data transmission state, an average value or a DC value of the first coupling capacitor and the second coupling capacitor is determined by a common mode voltage and an internal bias voltage of the first receiving input terminal and the second receiving input terminal.

[0063] Specifically, the average value or DC value of the coupling capacitance of P and N during data transmission is determined by the common mode voltage of RXP and RXN and the internal bias voltage. Since the average value or DC value across the coupling capacitance does not change when switching from the packet gap to the transmission state, the coupling capacitance does not need to undergo an additional charging and discharging process, and the internally received data will be presented at the correct level without causing erroneous reading.

[0064] In the present application, the second circuit structure has the following advantages compared with the first circuit structure: the bias inside the circuit is generated inside the chip, the bias voltage point can be set more flexibly, and the variation (PVTvariation) caused by the process angle, voltage and temperature changes can be reduced. For higher speed protocols that still use burst mode, the second circuit structure can avoid the bit error problem caused by the aforementioned capacitor charging and discharging without compromising signal integrity.

[0065] See also Figure 7 , which is a flow chart showing the principle of the implementation method described in the embodiment of the present application. Figure 7 As shown, the embodiment of the present application provides a method for realizing a multi-coupling structure based on signal transmission, which is applied to a circuit for realizing a multi-coupling structure based on signal transmission, wherein the circuit includes a differential signal input module, a coupling mode switching module and an analog front end, wherein the differential signal input module includes a first receiving input terminal and a second receiving input terminal, and the coupling mode switching module includes a coupling capacitor; the method specifically includes the following steps:

[0066] S71, using the differential value between the first receiving input terminal and the second receiving input terminal as the signal value input by the differential signal input module.

[0067] S72, according to the transmission state of the signal value, the coupling capacitor forms a path corresponding to the DC coupling function or the AC coupling function by turning on and off different switches, so as to realize switching between the DC coupling function and the AC coupling function.

[0068] S73, applying a DC bias voltage to the output voltage of the coupling mode switching module.

[0069] In this application, the requirements of DC coupling and AC coupling at the receiving end can be supported at the same time. High-speed signal transmission circuits often need to meet requirements such as signal integrity and internal circuit bias. AC coupling is suitable for situations where data of different logic levels need to be connected. In these cases, such as from the output of emitter coupled logic to the low-voltage differential signal level (LVDS), if DC coupling is used directly, the amplitude and common mode value of the signal will be distorted, destroying the integrity of the signal. At the same time, the analog front-end circuit at the receiving end of the high-speed circuit usually has requirements for the bias voltage range to ensure the correctness of the function and meet the performance standards. Figure 2-Figure 5 For example, if the voltages of VGP and VGN are too low, the transistors of the input circuit will be in a closed state, and if the voltages of VGP and VGN are too low, the internal transistors may be damaged. The present invention effectively solves the problems of coupling capacitor charging and discharging caused by conventional AC coupling in burst mode, as well as abnormal signal levels at the beginning of data transmission. The solution of the present application does not need to extend the preamble time at the beginning of the data transmission, thereby increasing more effective data transmission time for the system, increasing the effective bandwidth of the system, and improving the network speed of users using network communications.

[0070] The protection scope of the implementation method of the multi-coupling structure based on signal transmission described in the embodiment of the present application is not limited to the execution order of the steps listed in the present embodiment. All solutions implemented by adding, reducing or replacing steps in the prior art based on the principles of the present application are included in the protection scope of the present application.

[0071] The implementation circuit of the multi-coupling structure based on signal transmission provided in the embodiment of the present application can implement the implementation method of the multi-coupling structure based on signal transmission described in the present application, but the implementation device of the implementation method of the multi-coupling structure based on signal transmission described in the present application includes but is not limited to the structure of the implementation circuit of the multi-coupling structure based on signal transmission listed in the present embodiment, and all structural deformations and replacements of the prior art made according to the principles of the present application are included in the protection scope of the present application.

[0072] In the several embodiments provided in the present application, it should be understood that the disclosed circuits or methods can be implemented in other ways. For example, the circuit embodiments described above are only schematic, for example, the division of modules / units is only a logical function division, and there may be other division methods in actual implementation, such as multiple modules or units can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or modules or units, which can be electrical, mechanical or other forms.

[0073] The modules / units described as separate components may or may not be physically separated, and the components displayed as modules / units may or may not be physical modules, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules / units may be selected according to actual needs to achieve the purpose of the embodiments of the present application. For example, the functional modules / units in the various embodiments of the present application may be integrated into one processing module, or each module / unit may exist physically separately, or two or more modules / units may be integrated into one module / unit.

[0074] Those of ordinary skill in the art should further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0075] See also Figure 8 , which is a schematic diagram showing the structural principle of the receiver described in the embodiment of the present application. Figure 8 As shown, an embodiment of the present application provides a receiver, which includes: an implementation circuit of the multi-coupling structure based on signal transmission.

[0076] The implementation circuit of the multi-coupling structure based on signal transmission includes: a differential signal input module, including a first receiving input terminal and a second receiving input terminal, configured to use the differential value of the first receiving input terminal and the second receiving input terminal as the signal value input by the differential signal input module; a coupling mode switching module, configured to switch between a DC coupling function and an AC coupling function by turning on and off different switches according to the transmission state of the signal value; an analog front end, configured to apply a DC bias voltage to the output voltage of the coupling mode switching module; the coupling mode switching module includes a coupling capacitor, and the coupling capacitor forms a path corresponding to the DC coupling function or the AC coupling function by turning on and off different switches, and the output voltage of the coupling capacitor serves as the output voltage of the coupling mode switching module.

[0077] In one embodiment, the receiver comprises an optical module receiver.

[0078] The optical module receiver is arranged in an optical fiber serial communication circuit, the optical fiber serial communication circuit is connected to an optical cable terminal, and the optical cable terminal is connected to multiple optical network units; multiple optical network units share the same physical link in a time division multiplexing manner; each optical network unit sends out a short data packet, and the optical cable terminal receives the short data packets sent by each optical network unit in an intermittent mode, and after processing, transmits them as signal values ​​to the differential signal input module of the optical module receiver.

[0079] In one embodiment, a data valid signal sent by the optical module transmitter indicates a correct configuration mode of the optical fiber serial communication circuit, and the correct configuration mode includes controlling the time when different switches are turned on and off.

[0080] See also Fig. 9 , showing the application circuit structure diagram of the receiver described in the embodiment of the present application. In practical applications, the optical module receiver is arranged in an optical fiber serial communication circuit, and the optical fiber serial communication circuit is a Serdes circuit. SerDes is the abbreviation of Serializer / Deserializer in English, which is an interface device for realizing medium and long-distance high-speed communication. The SerDes interface is often selected as the physical layer implementation scheme of communication protocols such as PCI-Express, Gigabit Ethernet and optical fiber communication, and is widely used for high-speed interconnection between chips, boards and devices.

[0081] like Fig. 9As shown in the figure, in optical communication FTTH / FTTR (fiber to the home / room), when data is uploaded from ONU (optical network unit) to OLT (optical line terminal) through PON (passive optical network), multiple ONUs share a physical link in TDMA (time-division multiple-access). Each ONU sends a short data packet (burst packet), and OLT needs to receive the data sent by each ONU in burst mode.

[0082] In order to correctly receive the data sent by the ONU and maximize the use of the time-sharing bandwidth, the OLT needs to correctly recover the received data in the shortest possible time. In addition, similar to many high-speed protocols, the OLT needs to recover the data clock (clock-data-recovery, CDR) through the received data. As for the above-mentioned AC coupling, when receiving data in intermittent data packet mode, for differential signal transmission, the coupling capacitors at the P and N ends of the signal will be charged and discharged to the level of their corresponding ports during the data transmission gap (guard time). When switching from the data packet gap to normal data transmission, the capacitor will be charged and discharged to the level of the common mode voltage of the input port. Figure 6 As shown, since the capacitor needs time to charge and discharge, at the beginning of the data packet, the data will deviate from the correct level, resulting in received data and clock errors. Although the signal can be restored to the correct level before receiving data by extending the waiting or recovery time (pre-amble), this will shorten the time of valid data and reduce the effective time of transmission, thereby affecting the rate of the network. For this reason, the current general 1.25 / 2.5G PON transceiver chip requires the use of DC coupling on the link communicating with the MAC, but for the higher-speed 10G XGPON, considering the requirements including bias and signal integrity mentioned above, AC coupling is generally used. Therefore, the technical solution of the present application can meet the needs of supporting both DC coupling and AC coupling at the receiving end.

[0083] In the present application, the implementation method for accurately controlling the opening and closing time of the switch includes: using the data valid signal sent by the optical module transceiver to indicate the correct configuration mode of the circuit. A possible implementation method can be referred to Fig.10 The schematic diagram of the optical module output signal is shown.

[0084] See also Fig.10 , showing a data transmission and reception waveform diagram of the receiver according to the embodiment of the present application. Fig. 9 and Fig.10 As shown in the figure, after receiving the input optical signal, the OLT optical module transceiver will generate electrical signal data for the serdes through the internal limiting amplifier and output amplifier. At the same time as sending the data, it will also generate a data valid indication signal ( Fig.10 SD Output). This data valid signal is completely synchronized with the electrical signal data, so the data valid indication signal sent by the optical module can be used to switch the correct configuration mode of the circuit, that is, the on and off of different switches. For the second circuit structure, sw0 / sw1 is used as an example to further illustrate. When the SD output signal is low, sw0 / sw1 is opened (disconnected), and when the SD output signal is high, sw0 / sw1 is closed (turned on). The description of other switches is similar. For the first circuit structure, no data valid signal is required, and the control part of the chip only needs to configure each switch according to the required mode.

[0085] Taking the application of FTTH / FTTR as an example, the optical module receiver of the present application is set in the Serdes circuit. If the first circuit structure is adopted, the receiver will be configured to be in a DC coupled state. At this time, no matter whether the optical module transceiver is in the data transmission gap between different ONUs or a certain ONU is sending data, since there is no coupling capacitor between the receiver and the optical module transmitter, when entering the data receiving state from the data gap (idle) state, there will be no DC bias error caused by capacitor charging and discharging, thereby ensuring the correct data reception. If the second circuit structure is adopted, the data valid signal generated by the optical module is used, and when the data is invalid, the receiver is configured to Figure 4 In the state shown, the voltage of the coupling capacitor of the receiver is determined by the common mode voltage generated by the fixed level output of the optical module and the internal bias circuit. When the data valid signal indicates entering the data transmission state, the receiver is configured as Figure 5 At this time, the DC voltage of the coupling capacitor of the receiver is determined by the average value of the change level of the optical module (equal to the common mode voltage of the circuit) and the internal bias circuit. Figure 4 and Figure 5 The average DC voltage of the coupling capacitor is consistent, and no additional capacitor charging and discharging occurs during state transitions, so the internal analog front end can also receive data correctly.

[0086] It should be noted that, in addition to the Serdes circuit, the circuit in which the transceiver of the present application is located can also be Analog-to-Digital converters (analog-to-digital conversion circuit) or Ethernet circuit, etc.

[0087] The descriptions of the processes or structures corresponding to the above-mentioned figures have different emphases. For parts that are not described in detail in a certain process or structure, please refer to the relevant descriptions of other processes or structures.

[0088] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. A circuit for realizing a multi-coupling structure based on signal transmission, characterized in that: The circuit comprises: A differential signal input module, comprising a first receiving input terminal and a second receiving input terminal, configured to use a differential value between the first receiving input terminal and the second receiving input terminal as a signal value input by the differential signal input module; A coupling mode switching module is configured to switch between a DC coupling function and an AC coupling function by turning on and off different switches according to a transmission state of the signal value; the transmission state of the signal value includes a data packet gap state and a normal data transmission state; an analog front end configured to apply a DC bias voltage to an output voltage of the coupling mode switching module; The coupling mode switching module includes a coupling capacitor, and the coupling capacitor forms a path corresponding to a DC coupling function or an AC coupling function by turning on and off different switches, and the output voltage of the coupling capacitor serves as the output voltage of the coupling mode switching module; The coupling mode switching module further includes: a zeroth switching switch, a first switching switch, a second switching switch, a third switching switch, a fourth switching switch, a fifth switching switch and a sixth switching switch; In response to the transmission state of the signal value being in a data packet gap state, the zeroth switch and the first switch are disconnected, the second switch and the third switch are turned on, the common mode voltage of the first receiving input terminal and the second receiving input terminal is transmitted to the coupling capacitor input terminal, the output voltage of the coupling capacitor is connected to the DC bias voltage through the turned-on fifth switch and the sixth switch, and the fourth switch is turned on, further ensuring that the output voltage of the coupling mode switching module is equal to the DC bias voltage; The coupling mode switching module further includes: a bias resistor; in response to the transmission state of the signal value being in a normal data transmission state, the zeroth switching switch and the first switching switch are turned on, the second switching switch and the third switching switch are turned off, the fourth switching switch, the fifth switching switch and the sixth switching switch are turned off, and the common mode voltage of the first receiving input terminal and the second receiving input terminal is transmitted to the coupling capacitor input terminal, and the output voltage of the coupling capacitor is connected to the DC bias voltage through the bias resistor; The coupling capacitor includes a first coupling capacitor and a second coupling capacitor; in response to the transmission state of the signal value being in a normal data transmission state, the average value or DC value of the first coupling capacitor and the second coupling capacitor is determined by the common mode voltage and internal bias voltage of the first receiving input terminal and the second receiving input terminal.

2. A method for realizing a multi-coupling structure based on signal transmission, characterized in that: Applied to the implementation circuit of the multi-coupling structure based on signal transmission according to claim 1, the circuit includes a differential signal input module, a coupling mode switching module and an analog front end, the differential signal input module includes a first receiving input terminal and a second receiving input terminal, and the coupling mode switching module includes a coupling capacitor; the method includes: Using the differential value between the first receiving input terminal and the second receiving input terminal as the signal value input by the differential signal input module; According to the transmission state of the signal value, the coupling capacitor forms a path corresponding to the DC coupling function or the AC coupling function by turning on and off different switches, so as to realize switching between the DC coupling function and the AC coupling function; A DC bias voltage is applied to the output voltage of the coupling mode switching module.

3. A receiver, characterized in that: The receiver comprises: the circuit of claim 1.

4. The receiver according to claim 3, characterized in that The receiver comprises an optical module receiver; The optical module receiver is arranged in an optical fiber serial communication circuit, the optical fiber serial communication circuit is connected to an optical cable terminal, and the optical cable terminal is connected to a plurality of optical network units; Multiple optical network units share the same physical link in a time-division multiplexing manner; each optical network unit sends out a short data packet, and the optical cable terminal receives the short data packets sent by each optical network unit in an intermittent mode, and transmits the processed data packets as signal values ​​to the differential signal input module of the optical module receiver.

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