JP6384285B2 - Optical receiver module - Google Patents

Description

  The present invention relates to an optical receiver module.

  Conventionally, in an optical receiver module used for optical communication, a technique for reducing noise using a capacitor is known (see, for example, Patent Documents 1, 2, and 3). For example, in Patent Document 1, PD (Photo Diode) or APD (Avalanche Photo Diode) bias noise is removed by an RC filter using a resistor and a capacitor.

JP-A-7-022642 JP 2006-270616 A JP 2003-134051 A

  By the way, in recent years, optical transceivers (optical transceivers) having an optical transmission capacity expanded to 40 Gbps or 100 Gbps have become widespread in order to solve the bottleneck of the transmission capacity of communication between servers. In such an optical transceiver, each component is integrated in order to achieve high-density mounting accompanying an increase in transmission density. In such an integrated optical transceiver, the electrical wiring related to the optical reception module and the electrical wiring related to the optical transmission module are close to each other. As a result, crosstalk is likely to occur between the signal related to the optical reception module and the signal related to the optical transmission module, which may cause a problem due to crosstalk.

  Specifically, there is a possibility that the light reception sensitivity of the light reception module may be reduced by applying noise from a signal transmitted through the electrical wiring of the optical transmission module to a bias voltage transmitted through the electrical wiring of the optical reception module. Such a decrease in optical reception sensitivity cannot be sufficiently suppressed by simply removing noise using a capacitor.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical reception module that can suppress a decrease in optical reception sensitivity by reducing noise.

  An optical receiver module according to the present invention, as one aspect thereof, is an optical receiver module mounted inside an optical transceiver together with a signal wiring for supplying a drive signal to the optical transmitter module, from a bias power source in the optical transceiver. A first light receiving element that is supplied with a bias voltage and outputs an electrical signal corresponding to the received light intensity, and a first external wiring connected to a first external wiring for supplying the bias voltage from the bias power source to the first light receiving element. 1 connection terminal, a first internal wiring connecting the first connection terminal and the first light receiving element, and a second external wiring arranged closer to the signal wiring than the first external wiring. A second connection terminal connected to the bias power source via the second connection terminal, a second internal wiring for connecting the second connection terminal and the ground potential inside the optical receiver module, and a first internal wiring provided on the first internal wiring, 1 resistance and first co It has a first noise removing unit having a capacitor, disposed in the second internal wiring, and a second noise removing portion having a second resistor and a second capacitor, a.

  ADVANTAGE OF THE INVENTION According to this invention, the optical receiver module which can suppress the fall of optical receiving sensitivity by reducing noise can be provided.

It is a block diagram which shows the structure of the optical transceiver which concerns on this embodiment. It is a circuit diagram of the optical receiver module of the optical transceiver shown in FIG. It is a graph which shows the cutoff frequency of RC filter. FIG. 3 is a carrier mounting diagram of the optical receiving module shown in FIG. 2. It is a circuit diagram of the optical receiver module concerning a modification.

[Description of Embodiment of Present Invention]
First, the contents of the embodiments of the present invention will be listed and described.

  An optical receiver module according to the present invention, as one aspect thereof, is an optical receiver module mounted inside an optical transceiver together with a signal wiring for supplying a drive signal to the optical transmitter module, from a bias power source in the optical transceiver. A first light receiving element that is supplied with a bias voltage and outputs an electrical signal corresponding to the received light intensity, and a first external wiring connected to a first external wiring for supplying the bias voltage from the bias power source to the first light receiving element. 1 connection terminal, a first internal wiring connecting the first connection terminal and the first light receiving element, and a second external wiring arranged closer to the signal wiring than the first external wiring. A second connection terminal connected to the bias power source via the second connection terminal, a second internal wiring for connecting the second connection terminal and the ground potential inside the optical receiver module, and a first internal wiring provided on the first internal wiring, 1 resistance and first co It has a first noise removing unit having a capacitor, disposed in the second internal wiring, and a second noise removing portion having a second resistor and a second capacitor, a.

  In this optical receiver module, the second external wiring connected to the second internal wiring at the second connection terminal is more than the first external wiring connected to the first internal wiring at the first connection terminal. , Are arranged close to the signal wiring. That is, the second external wiring is disposed at a position closer to the signal wiring for supplying the drive signal to the optical transmission module than the first external wiring. For this reason, the noise of the signal on the transmission side transmitted through the signal wiring is more easily applied to the second external wiring than the first external wiring. Here, the second internal wiring connected to the second external wiring is connected to the ground potential. In other words, the second external wiring and the second internal wiring are dummy wirings that do not supply bias power to the light receiving element. Since such second external wiring can receive most of the noise of the signal on the transmission side, it is possible to suppress the noise from being transmitted to the first internal wiring that supplies the bias power to the first light receiving element. Can do. Thereby, the influence of the noise in a light receiving element can be reduced, and the fall of the optical receiving sensitivity in an optical receiving module can be suppressed.

  Further, the length from the second connection terminal to the second resistor in the second internal wiring may be shorter than the length from the first connection terminal to the first resistance in the first internal wiring. As a result, the section in which the noise before removal is transmitted from the second internal wiring to the first internal wiring can be shortened, and as a result, the noise transmitted from the second internal wiring to the first internal wiring is reduced. Can do.

  Further, the first external wiring is disposed between the second light receiving element, which is supplied with a bias voltage from the bias power supply and outputs an electric signal corresponding to the light receiving intensity, and the second external wiring. A third connection terminal connected to the bias power supply via the third external wiring; a third internal wiring connecting the third connection terminal and the second light receiving element; a first external wiring; A fourth connection terminal connected to the bias power source via a fourth external wiring arranged between the three external wirings, and a fourth connection terminal for connecting the fourth connection terminal and the ground potential inside the optical receiver module. Internal wiring, a third noise removing unit having a third resistor and a third capacitor provided in the third internal wiring, and a fourth resistor and a second provided in the fourth internal wiring. And a fourth noise removing unit having four capacitors. .

  The third external wiring is arranged so that the first external wiring is sandwiched between the third external wiring and the second external wiring. The fourth external wiring, which is a dummy wiring that does not supply bias power to the light receiving element, is disposed between the first external wiring and the third external wiring. That is, the second external wiring, the first external wiring, the fourth external wiring, and the third external wiring are arranged in the order close to the signal wiring. Since the second external wiring is arranged, noise is hardly transmitted to the first external wiring as described above. Even if noise is transmitted to the first external wiring, the fourth external wiring, which is a dummy wiring, is arranged between the first external wiring and the third external wiring. It is possible to suppress the noise from being transmitted to the third external wiring. That is, when the fourth external wiring receives the noise from the first external wiring, it is possible to suppress the noise from being transmitted to the third internal wiring that supplies the bias power to the second light receiving element.

  Further, the length from the fourth connection terminal to the fourth resistor in the fourth internal wiring may be shorter than the length from the third connection terminal to the third resistance in the third internal wiring. As a result, the interval in which the noise before removal is transmitted from the fourth internal wiring to the third internal wiring can be shortened, and as a result, the noise transmitted from the fourth internal wiring to the third internal wiring is reduced. be able to. Thereby, the influence of the noise in a light receiving element can be reduced, and the fall of the optical receiving sensitivity in an optical receiving module can be suppressed.

[Details of the embodiment of the present invention]
A specific example of an optical transmitter according to an embodiment of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to the claim are included.

  FIG. 1 is a diagram illustrating a configuration of an optical transceiver according to the present embodiment. The optical transceiver 1 (optical transceiver) is a 40 gigabit optical transceiver that transmits and receives a multiplexed optical signal in which, for example, four optical signals having different wavelengths in the 1300 nm band are multiplexed in a two-core bidirectional manner. This is a module that can be hot-swipped with respect to the layer. In the present embodiment, the optical transceiver 1 is described as a 40 gigabit optical transceiver, but the optical transceiver 1 may be a 100 gigabit optical transceiver. Standards regarding the external shape, terminal arrangement, electrical characteristics, and optical characteristics of such an optical transceiver are, for example, MSA (Multi-Source Agreement) standard QSFP + (Quad Small Form Factor Pluggable) and CFP (100G Form-factor Pluggable). Alternatively, it is defined by CFP2, CFP4, and the like.

  The optical transceiver 1 includes an optical reception module 10, an optical transmission module 20, and a printed circuit board 30.

  The optical receiving module 10 is mounted inside the optical transceiver 1 together with signal wiring (details will be described later) for supplying a driving signal to the optical transmitting module 20, and converts each of four 10 Gbps optical signals having different wavelengths into electrical signals. And output. The electrical signal output from the optical receiving module 10 is input to a CDR (Clock Data Recovery) (not shown) and the clock and data are separated, and then output to the host controller (external device) 40.

  The optical receiving module 10 includes an optical demultiplexer 11, a PD (Photo Diode) 12, and a TIA (Trans-Impedance Amplifier) 13. The optical demultiplexer 11 has a function of dividing the received multiplexed optical signal into optical signals of four wavelengths (λ1, λ2, λ3, λ4). As the optical demultiplexer 11, an element such as a dielectric multilayer filter or a diffraction grating can be used, for example.

  The PD 12 is a light receiving element that is supplied with a bias voltage from the bias power supply 33 in the optical transceiver 1 and outputs an electrical signal (current signal) corresponding to the received light intensity. The PD 12 includes four integrated PDs 12a to 12d. Each of the PDs 12a to 12d receives light of one wavelength among the light of four wavelengths divided by the optical demultiplexer 11.

  The TIA 13 is an IC that impedance-converts and amplifies the current signal input from the PD 12 and outputs it as a voltage signal.

  The optical transmission module 20 converts four 10 Gbps electrical signals independent of each other into optical signals having different wavelengths and outputs the optical signals. The optical transmission module 20 includes an LD (Laser Diode) 21 and an optical multiplexer 22.

  The LD 21 is a light emitting element that is driven in accordance with a drive signal supplied from a later-described LD modulation amplification unit 34 via a signal wiring 37. The LD 21 includes four LDs 21a to 21d integrated inside the optical transmission module. Each of the LDs 21 a to 21 d outputs optical signals having different wavelengths to the optical multiplexer 22. The optical multiplexer 22 combines the four optical signals output from the LDs 21a to 21d into one multiplexed optical signal and outputs it.

  A card edge connector 31, a control unit 32, a bias power source 33, and an LD modulation amplification unit 34 are mounted on the printed circuit board 30. The card edge connector 31 is an electrode that is provided at an end of the printed circuit board 30 and is inserted into a socket of the host controller 40. When the card edge connector 31 is inserted into the socket of the host controller 40, each of a plurality of opposing electrical terminals is electrically connected to each other and power is supplied from the host controller 40 to the optical transceiver 1. Is activated, and communication between the optical transceiver 1 and the host controller 40 becomes possible.

  The control unit 32 communicates with the host controller 40 via the card edge connector 31 and controls each component (TIA 13, bias power source 33, and LD modulation amplification unit 34) in the optical transceiver 1. The control unit 32 transmits / receives data for controlling or monitoring the optical transceiver 1 to / from the host controller 40 by serial communication. The control unit 32 can stop the optical output of the LD 21 of the channel by transmitting the LD driver circuit disable signal to an arbitrary channel of the LD modulation amplification unit 34. Further, when detecting a malfunction in the optical transceiver 1, the control unit 32 transmits an alarm signal to the host controller 40 and controls each component in the optical transceiver 1 based on the control signal from the host controller 40. The control unit 32 is a so-called one-chip microcomputer, FPGA (field-programmable gate array), CPLD (Complex Programmable Logic Device), or the like. Further, the control unit 32 may be a combination of a plurality of these circuits. Further, the control unit 32 is electrically connected to each of the optical transmission module 20 and the optical reception module by a predetermined signal line, and monitors the operation state of each module by an electric signal transmitted and received through the signal line. Or may be controlled.

  The bias power source 33 supplies a bias voltage to the PD 12 according to a control signal from the control unit 32. The bias voltage supplied from the bias power source 33 is supplied to the PD 12 via the bias line 35. The bias line 35 is a wiring outside the optical reception module 10 that extends from the bias power source 33 toward the optical reception module 10. The bias line 35 includes bias lines 35a to 35d (a plurality of external wirings). A bias voltage is supplied to the PD 12a (first light receiving element) via a bias line 35a (Ch3 bias line), and a bias voltage is supplied to the PD 12b (second light receiving element) via a bias line 35b (Ch2 bias line). , And a bias voltage is supplied to the PD 12c via the bias line 35c (Ch1 bias line), and a bias voltage is supplied to the PD 12d via the bias line 35d (Ch0 bias line).

  The LD modulation amplification unit 34 outputs a drive signal for modulating the output light of the LDs 21 a to 21 d in accordance with the control signal input from the control unit 32. The drive signal output by the LD modulation amplification unit 34 is input to the LDs 21 a to 21 d via the signal wiring 37. The LD modulation amplifying unit 34 is a 4ch Driver IC including four drive circuits that drive the four LDs 21a to 21d in parallel with different drive signals, and the same number of drive circuits as the four LDs 21a to 21d have different LDs 21a. To 21d. Each of the LDs 21a to 21d may require a bias signal serving as a reference for the drive signal, but these bias signals may be supplied from a bias circuit (not shown), or the LD modulation amplification unit 34. May be supplied together with the drive signal.

  Here, in the optical transceiver 1, since each component is mounted with high density and integrated, a signal wiring 37 that transmits a drive signal output from the LD modulation amplification unit 34 and a bias power supply 33 are output. The bias line 35 for transmitting the bias voltage is close. As a result, the electromagnetic wave radiated by the drive signal transmitted through the signal wiring 37 has an influence on the signal transmitted through the bias line 35 through the substrate and the space by electromagnetic field induction, and noise ( Hereinafter, this may be described as transmission noise). As a configuration for suppressing transmission noise from being included in the bias line, the optical transceiver 1 includes a dummy bias line 36.

  The dummy bias line 36 (second external wiring) is a wiring outside the optical receiving module 10 that extends from the bias power source 33 to the optical receiving module 10, and is a signal wiring 37 and a bias line 35 (more specifically, a bias line 35 a). ). That is, the dummy bias line 36 is disposed closer to the signal wiring 37 than the bias line 35. The bias line 35b (third external wiring) is disposed so as to sandwich the bias line 35a between the dummy bias line 36 and the bias line 35c sandwiches the bias line 35b between the bias line 35a. The bias line 35d is disposed so as to sandwich the bias line 35c between the bias line 35b and the bias line 35b. That is, the dummy bias line 36, the bias line 35a, the bias line 35b, the bias line 35c, and the bias line 35d are arranged in the order close to the signal wiring 37. For this reason, the transmission noise of the signal wiring 37 is most likely to be included in the signal transmitted through the dummy bias line 36, and then is easily included in the signal transmitted through the bias line 35a. Hereinafter, the detailed configuration of the optical reception module 10 related to the removal of transmission noise will be described with reference to FIG.

  FIG. 2 is a circuit diagram of the optical receiver module of the optical transceiver shown in FIG. In FIG. 2, the optical demultiplexer 11 is omitted from the components of the optical receiver module 10. As illustrated in FIG. 2, the optical reception module 10 includes a noise removing unit 14, a connection terminal 15, and a bias line 16. The TIA 13 receives the current signal generated by the PD 12, converts it into a voltage signal, amplifies it, and outputs a voltage signal. For example, when four current signals are input, the four voltage signals corresponding to the respective current signals are output from the TIA 13. The voltage signal output from the TIA 13 may be a single-phase signal or a differential signal.

  The bias line 16 is a wiring inside the optical receiver module 10 that is electrically connected to the bias line 35 at the connection terminal 15 and extends toward the PD 12. The bias line 16 includes four bias lines 16a to 16d. The connection terminal 15 includes four connection terminals 15a to 15d corresponding to the four bias lines 35a to 35d and the four bias lines 16a to 16d.

  The bias line 16a (first internal wiring) is connected to the bias line 35a (first external wiring) at the connection terminal 15a (first connection terminal), and connects the connection terminal 15a and the PD 12a. The bias line 16b (third internal wiring) is connected to the bias line 35b at the connection terminal 15b, and connects the connection terminal 15b and the PD 12b. The bias line 16c is connected to the bias line 35c at the connection terminal 15c, and connects the connection terminal 15c and the PD 12c. The bias line 16d is connected to the bias line 35d at the connection terminal 15d, and connects the connection terminal 15d and the PD 12d.

  The noise removing unit 14 is provided in the bias line 16 and includes an RC filter that reduces noise having a frequency higher than a predetermined frequency, and a bypass capacitor that reduces noise having a higher frequency than the RC filter. ing. Since the lower limit value of the noise frequency reduced by the RC filter is relatively lower than the lower limit value of the noise frequency reduced by the bypass capacitor, the noise reduced by the RC filter is hereinafter referred to as low frequency noise. The noise reduced by the bypass capacitor is referred to as high frequency noise. The noise removing unit 14 includes four noise removing units 14a to 14d. The noise removing unit 14a (first noise removing unit) is provided in the bias line 16a, and includes a resistor R3 (first resistor) and a capacitor C32 (first capacitor) as an RC filter, and a capacitor C31 as a bypass capacitor. have. The noise removing unit 14b (third noise removing unit) is provided in the bias line 16b, and the resistor R2 (third resistor) and the capacitor C22 (third capacitor) are used as RC filters as bypass capacitors. It has a capacitor C21. The noise removing unit 14c is provided on the bias line 16c, and includes a resistor R1 and a capacitor C12 as an RC filter, and a capacitor C11 as a bypass capacitor. The noise removing unit 14d is provided in the bias line 16d, and includes a resistor R0 and a capacitor C02 as an RC filter, and a capacitor C01 as a bypass capacitor. All the capacitors described above are connected to the ground.

  Capacitors C31, C21, C11, and C01 that reduce high-frequency noise in each of the noise removing units 14a to 14d have a capacitance of about several tens of pF to several hundreds of pF (for example, 470 pF) corresponding to a signal frequency of 100 Gbps, for example, 16 is arranged in the immediate vicinity of the PD 12 (more specifically, in the immediate vicinity of the cathode of the PD 12). That is, the capacitors C31, C21, C11, and C01 are arranged at positions closer to the PD 12 than the RC filter that reduces low frequency noise. Thereby, the capacitors C31, C21, C11, and C01 can be disposed in the vicinity of the high-frequency noise source, and high-frequency noise can be appropriately reduced. The high-frequency noise is generated when the PD 12 receives a high-speed optical signal and generates a high-speed current signal corresponding thereto.

  As the resistor and the capacitor constituting the RC filter, a resistor and a capacitor that realize a cutoff frequency of several MHz to several tens of MHz are used. Since the cutoff frequency is determined by resistance value × capacitor value, as shown in FIG. 3, the range of the cutoff frequency is determined when the resistance value and the capacitor value are determined.

  For example, in the SDH / SONETFrame signal (SRM64) of optical communication, the bit pattern of A1 (11110110) continues in 192 bytes in the head overhead portion, and then the long bit pattern of A2 (00101000) continues in 192 bytes. Thereby, when the low frequency noise of several MHz is generated, the low frequency noise can be reduced by the RC filter described above. The RC filter includes, for example, only one channel in the optical receiving module in order to reduce the inductance of the bias line 16 and reduce noise by shortening the line length of the bias line 16 from the PD 12 to the RC filter. In such a case, it is generally arranged to be as close as possible to the cathode of the PD 12. However, when a plurality of channels are included in the optical receiving module, it is preferable to change the arrangement of the RC filters according to the relative positions between the channels.

  Further, the optical receiving module 10 includes a dummy bias line 17 connected to the dummy bias line 36, a connection terminal 18 (second connection terminal), and a noise removing unit 19. The dummy bias line 17 (second internal wiring) is connected to the dummy bias line 36 at the connection terminal 18 and is not electrically connected to any PD 12 included in the optical reception module 10. Wiring. Unlike the bias line 16, the dummy bias line 17 is a dummy wiring that does not supply power to the PD 12 because it is not electrically connected to the PD 12.

  The dummy bias line 17 is provided with a noise removing unit 19. The noise removing unit 19 has the same configuration as the noise removing unit 14 described above, and includes an RC filter that reduces low frequency noise and a bypass capacitor that reduces high frequency noise. The noise removing unit 19 includes a resistor Rx (second resistor) and a capacitor Cx2 (second capacitor) as an RC filter, and a capacitor Cx1 as a bypass capacitor. As the resistor Rx and the capacitor Cx2, a resistor and a capacitor that realize a cut-off frequency of several MHz to several tens of MHz are used similarly to the resistor and the capacitor constituting the RC filter in the noise removing unit 14. Further, as the capacitor Cx1, a capacitor having a capacity of about several tens of pF to several hundreds of pF corresponding to a signal frequency of 100 Gbps is used as in the bypass capacitor of the noise removing unit 14. The capacitors Cx1 and Cx2 are both connected to the ground GND.

  Here, as described above, the transmission noise of the signal wiring 37 is most easily included in the signal transmitted through the dummy bias line 36. In the present embodiment, the length of the dummy bias line 17 connected to the dummy bias line 36 at the connection terminal 18 from the connection terminal 18 to the resistor Rx is the bias line 16a connected to the bias line 35a at the connection terminal 15a. The length from the connection terminal 15a to the resistor R3 is shorter. Hereinafter, the detailed configuration of the bias line 16 and the dummy bias line 17 will be described with reference to the carrier mounting diagram of the optical receiving module 10 shown in FIG. FIG. 4 is a carrier mounting diagram of the optical receiving module shown in FIG.

  As shown in FIG. 4, the patterns (connection terminals) mounted on the pattern formation surface 60x of the carrier 60 are electrically connected to each of the bias lines 16a to 16d and the dummy bias line 17 by wire bonding or resistance. It is formed by. The basic circuit configuration of each of the bias lines 16a to 16d is common to each other. That is, each of the bias lines 16a to 16d includes a connection terminal 15 provided at an end of the carrier 60, which is a connection terminal to the bias line 35, a wire bonding 61 having one end connected to the connection terminal 15, and one end A first pattern 62 connected to the other end of the wire bonding 61; a resistance of an RC filter having one end connected to the other end of the first pattern 62; a second pattern 63 connected to the other end of the resistance; Wire bonding 64 connecting the second pattern 63 and the capacitor of the RC filter, wire bonding 65 connecting the second pattern 63 and the bypass capacitor, and wire bonding 66 connecting the third pattern 67 provided with the bypass capacitor and the PD 12 ,have. The shape of the bias line 16 from the connection terminal 15 to the third pattern 67 is the same for the bias line 16a and the bias line 16d, and is the same for the bias line 16b and the bias line 16c.

  The dummy bias line 17 includes a connection terminal 18 provided at an end of the carrier 60, which is a connection terminal to the dummy bias line 36, a wire bonding 71 having one end connected to the connection terminal 18, and one end being a wire. A first pattern 72 connected to the other end of the bonding 71, a resistance of an RC filter having one end connected to the other end of the first pattern 72, a second pattern 73 connected to the other end of the resistance, The wire bonding 74 for connecting the two patterns 73 and the capacitor of the RC filter and the wire bonding 75 for connecting the second pattern 73 and the bypass capacitor are provided. The bias line 16 described above is electrically connected to the pattern (third pattern 67) provided with the PD 12 to supply power to the PD 12, whereas the dummy bias line 17 that is a dummy wiring is electrically connected to the PD 12. Is not connected.

  Here, when the bias line 16 and the dummy bias line 17 are compared, the first pattern 72 of the dummy bias line 17 is provided at the outer end portion of the pattern formation surface 60 x as compared with the first pattern 62 of the bias line 16. The distance from the connection terminal to the first pattern is short. That is, the wire bonding 71 of the dummy bias line 17 is shorter than the wire bonding 61 of the bias line 16. Further, the first pattern 72 of the dummy bias line 17 is shorter than the first pattern 62 of the bias line 16. For this reason, the length from the connection terminal 18 to the resistor Rx via the wire bonding 71 and the first pattern 72 in the dummy bias line 17 is the same as the length from the connection terminal 15 to the wire bonding 61 and the first pattern in the bias line 16. It is shorter than the length to reach the resistance through 62.

  Next, operations and effects of the optical receiver module 10 according to the present embodiment will be described.

  In the optical receiving module 10 according to the present embodiment, the dummy bias line 36 connected to the dummy bias line 17 at the connection terminal 18 is connected to the signal wiring 37 on the transmission side and the bias line connected to the bias line 16a at the connection terminal 15a. 35a. That is, the dummy bias line 36 is arranged at a position closer to the signal wiring 37 on the transmission side than the bias line 35. For this reason, the noise of the signal on the transmission side transmitted through the signal wiring 37 is more easily applied to the dummy bias line 17 than the bias line 35. This is because noise due to signals on the transmitting side is generated when electromagnetic waves generated by voltage and current change at high frequencies act on other electric circuits by electromagnetic field induction. This is because an electric circuit (bias line) spatially close to the signal wiring 37 is more susceptible to influence.

  Here, the dummy bias line 17 connected to the dummy bias line 36 extends toward the ground GND and is not electrically connected to any PD 12. In other words, the dummy bias line 36 and the dummy bias line 17 are dummy wirings that do not supply bias power to the PD 12. In such a dummy bias line 36, most of the noise of the signal on the transmission side is received and the noise can be released to the ground GND via the dummy bias line 17, so that the bias line 16 for supplying a bias power to the PD 12 is supplied to the bias line 16. It is possible to suppress the transmission of noise.

  Furthermore, the length from the connection terminal 18 to the resistor Rx via the wire bonding 71 and the first pattern 72 in the dummy bias line 17 is the same as the length from the connection terminal 15 to the wire bonding 61 and the first pattern 62 in the bias line 16. It is shorter than the length leading up to the resistance. As a result, the period during which the noise before removal is transmitted from the dummy bias line 17 to the bias line 16 by crosstalk can be shortened. As a result, the noise transmitted from the dummy bias line 17 to the bias line 16 can be reduced. Thereby, the influence of the noise in PD12 can be reduced and the fall of the optical receiving sensitivity in the optical receiver module 10 can be suppressed.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, a dummy bias line 36x (fourth external wiring) may be arranged between the bias line 35a and the bias line 35b as in the optical transceiver 1A shown in FIG. That is, the optical transceiver 1A includes a dummy bias line 36x disposed between the bias line 35a and the bias line 35b as a wiring outside the optical reception module 10A extending from the bias power supply 33 of the printed circuit board 30A to the optical reception module 10A. Yes. The optical reception module 10A includes a dummy bias line 17x, a connection terminal 18x (fourth connection terminal), and a noise removal unit 19x. The dummy bias line 17x (fourth internal wiring) is connected to the dummy bias line 36x at the connection terminal 18x and is not electrically connected to any PD 12 included in the optical reception module 10, and is inside the optical reception module 10A. Wiring.

  The dummy bias line 17x is provided with a noise removing unit 19x. The noise removing unit 19x (fourth noise removing unit) has the same configuration as the noise removing unit 19 described above, and includes a resistor Ry (fourth resistor) and a capacitor Cy2 (fourth capacitor) as an RC filter. The capacitor Cy1 is provided as a bypass capacitor. Capacitors Cy1 and Cy2 are both connected to the ground GND. The length from the connection terminal 18x to the resistor Ry in the dummy bias line 17x is shorter than the length from the connection terminal 15b to the resistor R2 in the bias line 16b.

  The bias line 35b is disposed so as to sandwich the bias line 35a between the bias line 35b and the dummy bias line 36. The dummy bias line 36x is disposed between the bias line 35a and the bias line 35b. That is, the dummy bias line 36, the bias line 35a, the dummy bias line 36x, and the bias line 35b are arranged in the order close to the signal wiring 37.

  Since the dummy bias line 36 is arranged, the electromagnetic wave radiated from the signal wiring 37 is absorbed by the dummy bias line 36 as described above, so that noise is not easily transmitted to the bias line 35a. Even if noise is transmitted to the bias line 35a, the dummy bias line 36x, which is a dummy wiring, is disposed between the bias line 35a and the bias line 35b. Thus, it is possible to suppress noise from being transmitted to the bias line 35b due to crosstalk.

  That is, the noise from the bias line 35a is received by the dummy bias line 36x, and the noise can be released to the ground GND via the dummy bias line 17x, so that the noise is transmitted to the bias line 16b that supplies the bias power to the PD 12b. Can be suppressed. Further, the length from the connection terminal to the resistor R2 of the noise removing unit is shorter in the dummy bias line 17x than in the bias line 16b. As a result, the period during which the noise before removal is transmitted from the dummy bias line 36x to the bias line 35a can be shortened, and as a result, the noise transmitted from the dummy bias line 36x to the bias line 35a can be reduced. Thereby, the influence of the noise in PD12 can be reduced and the fall of optical receiving sensitivity can be suppressed more.

  In addition, although it has been described that there are four PDs 12, the present invention is not limited to this, and there may be one or a plurality of PDs 12. Similarly, the number of bias lines 16 and noise removal units 14 is not limited to four, and may be any number corresponding to the number of PDs 12. In addition, although the light receiving element is a PD, the present invention is not limited to this, and another light receiving element such as an APD (Avalanche PhotoDiode) may be used.

  DESCRIPTION OF SYMBOLS 1,1A ... Optical transceiver 10, 10A ... Optical receiving module, 12a, 12b ... PD, 14a, 14b, 19, 19x ... Noise removal part, 15a, 15b, 18, 18x ... Connection terminal, 16a, 16b ... Bias line 17, 17x ... dummy bias line, 20 ... optical transmission module, 21 ... LD, 33 ... bias power supply, 35a, 35b ... bias line, 36, 36x ... dummy bias line, 37 ... signal wiring, C22, C32, Cx2, Cy2 ... capacitor, R2, R3, Rx, Ry ... resistance.

Claims (4)

An optical receiver module mounted inside an optical transceiver together with signal wiring for supplying a drive signal to the optical transmitter module,
A first light receiving element which is supplied with a bias voltage from a bias power source in the optical transceiver and outputs an electric signal corresponding to the received light intensity;
A first connection terminal connected to a first external wiring for supplying the bias voltage from the bias power source to the first light receiving element;
A first internal wiring for connecting the first connection terminal and the first light receiving element;
A second connection terminal connected to the bias power supply via a second external wiring disposed closer to the signal wiring than the first external wiring;
A second internal wiring for connecting the second connection terminal and a ground potential inside the optical receiver module;
A first noise removing unit having a first resistor and a first capacitor provided in the first internal wiring;
Have a, a second noise removing portion having the second provided inside the wiring, a second resistor and a second capacitor,
The second internal wiring is not electrically connected to any of the one or more light receiving elements when the light receiving module has one or more light receiving elements including the first light receiving element. module.   The length from the second connection terminal to the second resistor in the second internal wiring is shorter than the length from the first connection terminal to the first resistance in the first internal wiring. The optical receiver module according to claim 1. A second light receiving element which is supplied with a bias voltage from the bias power source and outputs an electric signal corresponding to the light receiving intensity;
A third connection terminal connected to the bias power source via a third external wiring disposed so as to sandwich the first external wiring between the second external wiring;
A third internal wiring for connecting the third connection terminal and the second light receiving element;
A fourth connection terminal connected to the bias power source via a fourth external wiring disposed between the first external wiring and the third external wiring;
A fourth internal wiring connecting the fourth connection terminal and the ground potential inside the optical receiver module;
A third noise removing unit having a third resistor and a third capacitor provided in the third internal wiring;
Wherein provided on the fourth internal wiring, further possess a fourth noise removing section having a fourth resistor and a fourth capacitor, a,
3. The fourth internal wiring according to claim 1, wherein when the one or more light receiving elements further include the second light receiving element, the fourth internal wiring is not electrically connected to any of the one or more light receiving elements. The optical receiver module described.   The length from the fourth connection terminal to the fourth resistor in the fourth internal wiring is shorter than the length from the third connection terminal to the third resistance in the third internal wiring. The optical receiver module according to claim 3.

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