TWI220600B - Interface circuit for optical fiber transceiver - Google Patents

Abstract

An interface circuit for an optical fiber transceiver is provided. The output of a signal detection pin of the optical fiber transceiver is connected to the interface circuit to obtain the physical layer (PHY). The data signals inputting DC voltage bias for a receiving pin of network to PHY are not varied while an optical fiber is not plugged into the optical fiber transceiver or the link signal is not received by the optical fiber transceiver, but the normal data signals are received by PHY while an optical fiber is plugged into the optical fiber transceiver. Therefore, the PHY do not require a signal detection pin and the cost of PHY is reduced.

Description

1220600 V. Description of the invention (1) Technical field to which the invention belongs The present invention relates to a network interface, and more particularly, to an optical fiber transceiver (H) interface circuit. Previous technology Due to the development of electronic technology, computers and various information digitizing devices have become increasingly popular. In order to achieve the purpose of resource sharing, the network has become a necessary configuration for information exchange. In a variety of different network configurations, because Ethernet has the characteristics of easy access, convenient installation, and fast transmission speed, Ethernet-related equipment has flourished, and its transmission rate has also evolved from 10Mbps to 100Mbps. Even lGbps. In an Ethernet device, whether it is a network device such as an Ethernet switch or a network card, the network physical layer (PHY) connected to the controller is used to cooperate with the access twisted pair. The pair of transceivers or optical fiber transceivers that access the fiber are used to receive packets on the network to achieve the purpose of information exchange and resource sharing. Please refer to Figure 1 'It is a conventional optical transceiver interface circuit. The conventional optical transceiver interface circuit 1 0 0 is used as the optical transceiver 1 1 0 and the network physical layer 1 2 0 The interface is mainly used to provide the differential data signal pins RX + and RX received by the optical fiber receiver 110, and the differential data signal pins received by the network physical layer 120 and the DC for the work of RXIM. Bias, and provides a transmission path for differential data signals. In the first figure, the DC bias voltage of the differential data signal pin r X + received by the optical fiber receiver 11 〇 is obtained by dividing the resistance R P1 and R P2.

H554t.wf.ptd Page 6 1220600 V. Description of the invention (2) The DC bias voltage of the received differential data signal pin RX- of device 1 1 0 is obtained by dividing the resistance RM1 and RM2, and the network entity The DC bias voltages of the differential data signal pins RXIP and RXIM received by the layer 120 are obtained by dividing the resistors Rup and Rdn, and input through the resistors RP 3 and RM3, respectively. Capacitors Cbp and Cbm are used to isolate the DC bias on both sides and provide a transmission path for differential data signals. In addition, in order to confirm whether the optical transceiver 1 10 is inserted into the optical fiber and connected to the opposite node, the optical transceiver 1 10 will also have a signal detection pin SD to send a detection signal to the network physical layer. 1 2 0, so that the media access controller (Media Access Controller, M AC for short) connected to the physical layer of the network can learn this message. Although this is the most direct detection method, for φ at the network physical layer 120 or the integrated circuit integrating the network physical layer 120 and the media access controller, a signal detection pin SD must be added. No further cost savings were possible. SUMMARY OF THE INVENTION In view of this, the present invention provides an optical fiber receiver interface circuit, so that the network physical layer connected to this optical fiber receiver interface circuit can omit the signal detection pin and still know the fiber insertion Or not to further save costs. In order to achieve the above and other objectives, the present invention provides an optical fiber transceiver interface circuit, which can be applied as an interface between an optical fiber transceiver and a physical layer of a network. The optical transceiver interface circuit includes: a first biasing unit for providing a DC bias of the first receiving pin of the optical fiber receiver, and a DC bias for providing a second receiving pin of the optical fiber receiver. A second biasing unit for

11554t.wf.ptd Page 7 1220600 V. Description of the invention (3) A third bias unit that provides a DC bias voltage for the first receiving pin of the network physical layer, and provides a second receiving pin of the network physical layer A fourth biasing unit with a direct current bias of four bits, coupled to the first biasing unit and the third biasing unit, for isolating the direct current biasing of the first biasing unit and the third biasing unit, and providing a data signal The first capacitor of the transmission path and the second biasing unit and the fourth biasing unit are coupled to isolate the DC bias voltage of the second biasing unit and the fourth biasing unit and provide the first of the transmission path of the data signal. Two capacitors. The DC bias voltage of the third bias unit is provided by the signal detection pin of the optical fiber receiver. In one embodiment, the first bias unit of the optical fiber receiver interface circuit includes a first resistor, a second resistor, and a third resistor. One end of the first resistor is coupled to the power source, and the other end is coupled to the first receiving pin of the optical fiber transceiver. One end of the second resistor is coupled to the first receiving pin of the optical fiber transceiver, and the other end is coupled to the first A capacitor; and one end of the third resistor is coupled to the first capacitor, and the other end is grounded. In one embodiment, the second bias unit of the optical transceiver interface circuit includes a first resistor, a second resistor, and a third resistor. One end of the first resistor is coupled to the power source, and the other end is coupled to the second receiving pin of the optical fiber transceiver; one end of the second resistor is coupled to the second receiving pin of the optical fiber transceiver, and the other end is coupled to the second A capacitor; and one end of the third resistor is coupled to the second capacitor, and the other end is grounded. In one embodiment, the third bias unit of the optical transceiver interface circuit includes a first resistor and a second resistor. One end of the first resistor is coupled to the signal detection pin of the optical fiber receiver, and the other end is coupled to the network physical layer.

11554t.wf. Pt.d Page 8 1220600 V. Description of the invention (4) The first receiving pin and the first capacitor; and one end of the second resistor is coupled to the first receiving pin and the first capacitor of the network physical layer. , The other end is grounded. In one embodiment, the third bias unit of the optical fiber receiver interface circuit includes a Zener Diode and a resistor. Among them, one end of the audit diode is coupled to the signal detection pin of the optical fiber receiver, and the other end is coupled to the first receiving pin and the first capacitor of the network entity layer; and one end of the resistor is coupled to the network entity. The first receiving pin of the layer and the first capacitor are connected to the other end. In one embodiment, the fourth bias unit of the optical transceiver interface circuit includes a first resistor and a second resistor. One terminal of the first resistor is coupled to the power source, and the other terminal is coupled to the second receiving pin and the second capacitor of the network physical layer; and one terminal of the second resistor is coupled to the second receiving pin and the Two capacitors, the other end is grounded. In one embodiment, the first receiving pin of the network entity layer of the optical fiber transceiver interface circuit is the positive end of the differential data signal, and the second receiving pin of the network entity layer is the differential data signal. Negative side. In an embodiment, the first receiving pin of the optical fiber transceiver of the optical transceiver interface circuit is the positive end of the differential data signal, and the second receiving pin of the optical fiber transceiver is the differential data signal. Negative side. As can be seen from the above description, the optical fiber receiver interface circuit provided by the present invention can make the network physical layer connected to the optical fiber receiver interface circuit eliminate the signal detection pin, so the manufacturing can be further saved. Cost 0 is to make the above and other objects, features, and advantages of the present invention clearer.

11554twf .pt.d Page 9 1220600 V. Description of the invention (5) It is easy to understand. The following is a detailed description of the preferred embodiment with the accompanying drawings as follows: Implementation: Please refer to Figure 2 It is a fiber optic receiver interface circuit according to the first embodiment of the present invention. As shown in the figure, the optical transceiver interface circuit 200 is used as an interface between the optical transceiver 2 110 and the network physical layer 220, and the optical transceiver 2 10 receives a signal of light from an optical fiber. After being converted into electrical differential data signals, the first receiving pin RX + of the optical fiber transmitter 2 10, that is, the positive end of the differential data signal, and the second receiving pin RX-, that is, The negative terminal of the differential data signal is output. As shown in the figure, the optical fiber transceiver interface circuit 200 includes: a first biasing unit 201, a second biasing unit 202, a third biasing unit 203, a fourth biasing unit 204, a first capacitor 205, and第二 Capacitor 206. The first biasing unit 201 includes a resistor RP1, a resistor RP2, and a resistor RP3. Among them, one end of the resistor RP1 is coupled to the power supply VDD, and the other end is coupled to the first receiving pin RX + of the optical transceiver 21 0; one end of the resistor RP2 is coupled to the first receiving pin RX + of the optical transceiver 2 1 0 The other end is coupled to the first capacitor 2 05; and one end of the resistor RP 3 is coupled to the first capacitor 2 05, and the other end is grounded. The second biasing unit 202 includes a resistor RM1, a resistor RM2 and a resistor R M 3. Among them, one end of the resistor R Μ 1 is coupled to the power supply VDD, and the other end is coupled to the second receiving pin RX-of the optical fiber transceiver 2 1 0; one end of the resistor R Μ 2 is coupled to the first optical fiber receiver 2 1 0 Two receiving pins RX-, the other end is coupled to the second capacitor 2 0 6; and one end of the resistor RM3 is coupled to the second capacitor 2 0 6, and the other end is connected

11554t.wf.ptd Page 10 1220600 V. Description of the invention (6) Ground 0 The third bias unit 203 includes a resistor RP 4 and a resistor RP5. Among them, one end of the resistor RP4 is coupled to the signal detection pin SD of the optical fiber transceiver 210, and the other end is coupled to the first receiving pin RXIP of the network physical layer 220, which is the positive end of the differential data signal. And the first capacitor 205; and one end of the resistor RP5 is coupled to the first receiving pin RXIP and the first capacitor 205 of the network physical layer 225, and the other end is grounded. The fourth biasing unit 204 includes a resistor RM4 and a resistor RM5. Among them, one end of the resistor RM4 is coupled to the power source VCC, and the other end is coupled to the second receiving pin RXI M of the network entity layer 220, that is, the negative terminal of the differential data signal and the second capacitor 206; and one end of the resistor RM5 The second receiving pin RXIM and the second capacitor 206 are coupled to the network entity layer 220, and the other end is grounded. In the embodiment of FIG. 2, the power source VDD is 5 V and the power source VCC is 2.5 V. The DC bias voltage of the first receiving pin RX + of the optical fiber transceiver 210 is provided by the voltage divider of the resistor RP1, the resistor RP2 and the resistor RP3. For 3ν, the DC bias voltage of the second receiving pin RX- of the optical fiber receiver 21 is provided by the resistor RM1, the resistor RM2, and the resistor RM3 divided voltage, which is also about 3V. The second receiving pin of the network physical layer 220 is provided by the resistor RM4 and the resistor RM5 divided voltage of about 2.0V, and the DC bias of the first receiving pin RXIP of the network is provided by the resistor RP4 and the resistor RP5 divided voltage. It changes with the optical fiber receiving signal ^ = signal output pin SD. 6 i u &

Due to this, the output of the signal of the fiber receiver 210 when detecting D is about 4V ′ When the fiber is not connected, about 3 2v is connected to the first fiber. The electric sight 4 used in the embodiment is in phase with the resistance of the resistor RP5 ^ iber #

11554twf, pt.d Page 11 1220600 V. Description of the invention (7) When the receiver 2 1 0 is connected to the optical fiber, the DC bias input to the first receiving pin RXIP of the network entity layer 2 2 0 and the input to the network The DC bias voltage of the second receiving pin RXI M of the physical layer 2 2 0 is also 2 · 0 V, so that the first receiving pin RX IP and the second receiving pin RXIM of the physical layer 2 2 0 are transmitted. The data signal is shown in Figure 3, so that the operational amplifier (not shown) in the network entity layer 220 can correctly convert the received differential data signal into a digital data signal, and use the received digital data Signal to determine that the fiber optic receiver 2 10 is a connected fiber. In addition, when the optical fiber transmitter 2 10 is not connected to an optical fiber, the DC bias voltage input to the first receiving pin RX IP of the network physical layer 2 2 0 is 3.2 V / 2 = 1. 6V, which is less than The DC bias voltage of 2 · 0 V input to the second receiving pin RXIM of the network entity layer 2 2 0 makes the first receiving pin RX IP and the second receiving pin RXIM of the network entity layer 2 2 0 The data signal transmitted on the network is shown in Figure 4. Because the resistance values of the resistors RP2, RP3, RM2, and RM3 are appropriately selected, the data signals transmitted on the first receiving pin RX IP and the second receiving pin RXI M of the network physical layer 2 2 0, As shown in Fig. 4, 0.13 V fluctuates between the DC bias voltages of 1.6 V and 2.0 V, respectively. Therefore, the data signal transmitted on the first receiving pin RXI P of the network physical layer 220 will remain smaller than the data signal transmitted on the second receiving pin RXI M, so that the operational amplifier in the network physical layer 220 The output (not shown) is maintained at a low level, and it can be known that the optical fiber receiver 210 is not connected to an optical fiber. Among them, as shown in FIG. 2, the first capacitor 205 and the second capacitor 206 are used to isolate the DC bias voltage of the first biasing unit 201 and the third biasing unit 203 and the second biasing unit, respectively. 2 0 2 and the fourth bias unit

11554t.wf.ptd Page 12 ^ 20600 Fifth invention description (8) _ 2 In addition to the DC bias, and can provide information Xun Meng kind of eyesight reference Ϊ 5 Figure, which is based on the second path . Heavy fiber receiver interface circuit. As shown in the figure, one of the two embodiments of the second embodiment of the road 5000 series is used as the optical fiber receiver 5 丨 Warehouse = optical fiber receiver interface electrical ^ special receiver 510 receives the signal vapor layer from the optical fiber The interface between 5 2 0, after the data signal is moved, it is converted to the electrical difference by the optical fiber receiver ^ 'and the positive end of the differential data signal, and the second receiving pin RX +, also The negative terminal of the data signal is output. ? The digits are-, that is, the differential as shown in the figure "this optical fiber receiver interface voltage unit 501, second bias unit 502, third" includes: the first bias bias unit 504, the first capacitor 505, and the second The first bias unit 501 and the second bias capacitor. 5 0 6 ° pressing unit 5 04, the first capacitor 505 and the second capacitor \ early 705 0 2, the fourth bias coupling relationship is almost the same as that in Figure 2, only the composition and bias Different pressures have different proportional relationships, and the third value ^ due to @ 所 ^ of the DC component is the Zener Diode Zd ^ \ pressure as early as 7 ° 5 0 3 One end of the body Zd is connected to the fiber optic cable. Its pin, the other end is connected to the first of the network physical layer 5 2 0 and detects the-capacitor 5G5, and the-terminal of the resistor RP4-is connected to the pin fXlP and the first receiving pin RXIP and the first A capacitor 505 is connected to the other end of X Beans 5 2 0. In the embodiment of FIG. 5, the power supply VDD is 5 v, and the power supply vcc is 2.5 V. The resistor RP1, resistor RP2, and resistor RP3 divide the voltage to provide the DC bias of the first receiving pin RX + of the optical fiber receiver 5 1 0. The voltage is about 3 V. The second connection of the fiber optic receiver 51 0 is provided by the resistor RM1, resistor RM2 and resistor RM3.

11554t.wf.ptd Page 13 1220600 V. Description of the invention (9) The DC bias of the receiver pin RX- is about 3 V. The resistor RM4 and resistor RM5 divide the voltage to provide the second reception of the network physical layer 5 2 0 The DC bias voltage of the pin RX I M is about 1.25V. The DC bias voltage of the first receiving pin RXIP of the network entity layer 520 is provided by the audit diode Zd and the resistor RP4 along with the optical fiber receiver 5 1 The 0 signal changes the output of the pin SD. Since the signal detection pin SD of the optical transceiver 5 10 has an output of about 4 V when the optical fiber is connected, and about 3.2 V when no optical fiber is connected, the dipole of this embodiment is The Zd voltage of the body is selected to be 2.7V, so that when the optical fiber receiver 5 1 0 is connected to the optical fiber, the DC bias voltage input to the first receiving pin RXIP of the network physical layer 5 2 0 is 1 · 3 V, which is close to the DC bias input to the second receiving pin RXI M of the network physical layer 5 2 0, so that the first receiving pin RX IP and the second receiving pin RXIM of the network physical layer 5 2 0 The data signal transmitted on the network can be correctly converted into a digital data signal by an operational amplifier (not shown) in the network physical layer 5 2 0, and the optical fiber receiver 5 1 0 is determined by the received digital data signal. The fiber is connected. In addition, when the optical fiber receiver 5 10 is not connected to an optical fiber, the DC bias voltage input to the first receiving pin RX IP of the network entity layer 520 is 3.2V-2.7V to 0.5V, which is less than the input to the network. The physical bias of the second receiving pin RXI M of the physical layer 520 is 1.25 V, so that the data transmitted on the first receiving pin RX IP and the second receiving pin RXIM of the physical layer 5 2 0 of the network The signal can also be similar to that shown in Figure 4. Because the resistance values of resistor RP2, resistor RP3, resistor RM2, and resistor RM3 are appropriately selected, the data signals transmitted on the first receiving pin RXIP and the second receiving pin RXI M of the network physical layer 5 2 0, It can fluctuate 0.2 V between DC bias voltages of 0.5 V and 1, 2 5 V,

11554t.wf.ptd Page 14 1220600 V. Description of the Invention (ίο) Therefore, the data signal transmitted on the first receiving pin RXIP of the network entity layer 5 2 0 will remain smaller than the second receiving pin RXI Μ The transmitted data signal makes the output of the operational amplifier (not shown) in the network physical layer 5 2 0 maintained at a low level, and it can be known that the optical fiber receiver 5 1 0 is not connected to the light. An optical fiber receiver interface circuit is invented, so that the network physical layer or the integrated circuit that integrates the network physical layer and the media access controller can still identify the optical fiber without the need for signal detection pins Insert it or not to further save costs. Although the present invention has been disclosed in the preferred embodiment as above, it is not intended to limit the present invention. Any person skilled in the art can make various changes and decorations without departing from the spirit of the present invention < 1 and the scope. Therefore, the scope of protection of the present invention shall be determined by the scope of the appended patent application.

11554twf. Pt.d Page 15 1220600 Brief description of the diagram The first diagram shows a conventional optical fiber receiver interface circuit; the second diagram shows an optical fiber receiver interface circuit according to the first embodiment of the present invention; Figure 3 is a schematic diagram of the data signal when the optical fiber receiver is connected to the optical fiber according to the first embodiment of the present invention; Figure 4 is a schematic diagram of the data signal when the optical fiber receiver is not connected to the optical fiber according to the first embodiment of the present invention; And FIG. 5 is a circuit diagram of an optical fiber receiver interface according to a second embodiment of the present invention. Graphical labeling explanation: 100 conventional optical transceiver interface circuit 1 1 0, 2 1 0, 5 1 0 optical transceiver 120, 220, 520 network physical layer 2 0 0, 5 0 0 optical transceiver interface Circuit 201, 501 First bias unit 202, 502 Second bias unit 203, 503 Third bias unit 204, 504 Fourth bias unit 205, 505 First capacitor 206, 506 Second capacitor

11554t.wf. Ptd Page 16

Claims (1)

1220600 VI. Scope of patent application1. An optical fiber transceiver interface circuit suitable for use as an interface between an optical fiber transceiver and a network physical layer, including: a first biasing unit for providing the optical fiber transceiver A DC bias voltage of a first receiving pin; a second biasing unit for providing a DC bias of a second receiving pin of the optical fiber transceiver; a third biasing unit for providing the network A DC bias voltage of the first receiving pin of the physical layer; a fourth biasing unit for providing a DC bias voltage of the second receiving pin of the physical layer of the network; a first capacitor coupled to the first bias The voltage unit and the third bias unit are used to isolate the DC bias of the first bias unit and the third bias unit and provide a data signal transmission path; and a second capacitor coupled to the second bias unit The bias unit and the fourth bias unit are used to isolate the DC bias of the second bias unit and the fourth bias unit and provide a data signal transmission path; wherein the DC of the third bias unit is Bias is transmitted by this fiber One signal detection pins are provided. 2. The optical fiber receiver interface circuit according to item 1 of the patent application scope, wherein the first bias unit includes: a first resistor, one end of the first resistor is coupled to a power source, and the other end is coupled to the optical fiber A first receiving pin of the transceiver; a second resistor, one end of which is coupled to the first receiving pin of the optical fiber transceiver, and the other end of which is coupled to the first capacitor; and 11554twf.ptd Page 17 1220600 6. Scope of patent application A third resistor, one end of the third resistor is coupled to the first capacitor, and the other end is grounded. 3. The optical fiber receiver interface circuit according to item 1 of the patent application scope, wherein the second bias unit includes: a first resistor, one end of the first resistor is coupled to a power source, and the other end is coupled to the optical fiber A second receiving pin of the transceiver; a second resistor, one end of which is coupled to the second receiving pin of the optical fiber transceiver, and the other end of which is coupled to the second capacitor; and a third resistor, One terminal of the third resistor is coupled to the second capacitor, and the other terminal is grounded. 4. The optical fiber receiver interface circuit according to item 1 of the scope of the patent application, wherein the third bias unit includes: a first resistor, one end of the first resistor is coupled to the signal detection pin, and the other end A first receiving pin coupled to the network physical layer and the first capacitor; and a second resistor, one end of which is coupled to the first receiving pin of the network physical layer and the first capacitor, The other end is grounded. 5. The optical fiber receiver interface circuit according to item 1 of the scope of the patent application, wherein the third bias unit includes: an audit diode, and one end of the audit diode is coupled to the signal detection pin. The other end is coupled to the first receiving pin of the network physical layer and the first capacitor; and a resistor, one end of the resistor is coupled to the first receiving pin of the network physical layer and the first capacitor, The other end is grounded. 11554t.wf.ptd Page 18 1220600 6. Application for patent scope 6 · The optical fiber receiver interface circuit described in item 1 of the patent application scope, wherein the fourth bias unit includes: a first resistor, the first One end of the resistor is coupled to a power source, the other end is coupled to the second receiving pin of the network physical layer and the second capacitor; and a second resistor, one end of the second resistor is coupled to the first of the network physical layer. Two receiving pins and the second capacitor, and the other end is grounded. 7 · The optical fiber receiver interface circuit described in item 1 of the scope of patent application, wherein the first receiving pin of the network physical layer is the positive end of the differential data signal, and the second receiving of the network physical layer is The pin is the negative end of the differential data signal. 8. The optical transceiver interface circuit as described in the first item of the patent application scope, wherein the first receiving pin of the optical transceiver is the positive end of a differential data signal, and the second receiving of the optical transceiver The pin is the negative end of the differential data signal. 11554twf, pt.d p. 19