Abstract: A method for enabling a calling user to establish a communication session with a called user, the calling user being associated with at least one calling user device and the called user being associated with at least one called user device, wherein the communication session can be established through a plurality of possible communication services and provisioning of said plurality of possible communication services is enabled through a corresponding plurality of communication service actuators, includes: a) receiving from the at least one calling user device, a request to establish a communication session with the called user, b) determining if, among said plurality of possible communication services, there is at least one communication service currently available to establish a communication session with the called user at the at least one called user device, based on current context information on the called user, c) in the affirmative case of b), selecting one of the at least one currently available commun

Abstract: Systems, methods, and equipment for use in the management of network topology and bandwidth for computing networks are provided. In an illustrative implementation of a device acting as a patch panel is provided. The patch panel works on both the physical wire and on the frequencies of the wire to route data to appropriate destination points. For example, both ADSL and telephony could be bridged among copper wires, using several independent busses. Home Phone Network Alliance Association (HPNA) standardized data could either be bridged among wires, or connected to an internal switching device, that would store and forward the native Ethernet packets used by HomePNA in a way similar to that done by Ethernet switches today. Additionally, an Ethernet uplink could attach the HPNA ports to a larger network or to a DSL Modem, and HPNA/ADSL could be removed from wires that might have privacy concerns or otherwise need filters to perform properly.

Abstract: A telecommunications module (10) has contacts (12, 14, 16) for connecting wires therewith, the contacts (12, 14, 16) being arranged in a number of substantially parallel rows, which is three or a multiple of three, at least one row of contacts (12, 14, 16) which is assigned to transmit a specific signal, such as a POTS, a line or a DSLAM signal, being assigned to transmit a different signal than any adjacent row of contacts within each multiple of three rows.

Abstract: The invention is a compact embedded modem that meets global telephone standards with its interface constructed in a single-in-line form factor. The modem in single-in-line form factor, namely SIP modem, can be integrated into a host system through a single-in-line header socket. The SIP interface includes TIP and RING signals for connecting to a phone line, isolation spacers, ground pin, power pin, and digital signals for transferring data to and from the host. The digital interface can be configured to operate in serial connection or in parallel connection to the host, selectable by user.

Abstract: Embodiments of the present invention relate to systems and methods for an electronic hook switch for customer premises equipment. In an embodiment, a system includes a first lead configured to be coupled to a tip wire and a second lead and the second lead to a ring wire. A diode bridge is coupled to the first lead and the second lead had a positive output. A low side switch is coupled to the positive output of the diode bridge without a high side switch between the low side switch and the positive output of the diode bridge.

Abstract: A system and method for transmitting information includes a first driver circuit configured to generate a first component signal of a differential signal at a first polarity. The system includes a second driver circuit configured to generate a second component signal of the differential signal at a second polarity. The first and second component signals are biased to form biased first and second component signals. A differential amplitude of a combination of the biased first and second component signals is less than a corresponding differential amplitude of the differential signal. The system includes an offset signal circuit in communication with the first and second driver circuits. The offset signal circuit is configured to generate an offset signal for offsetting the biased first and second component signals. A combination of the offset and biased first and second component signals forms the differential signal.

Abstract: An integrated connecting device for coupling a communication link to a powered device (PD) in a system for supplying power to the PD over the communication link. The integrated connecting device has a housing configured for providing connection to the PD external with respect to the housing, communication interface circuitry coupled to the communication link for supporting data communication of the PD over the communication link, and power interface circuitry coupled to the communication interface circuitry for implementing a power supply protocol performed to supply power to the PD over the communication link. The communication interface circuitry and the power interface circuitry being held by the housing.

Abstract: A midspan power adapter is provided for use in a balanced communication system, such as an Ethernet system, where differential signals are transmitted between two devices. The adapter passes data signals through, and provides power to an end device, such as an IP phone, with significantly less contribution to the electromagnetic emissions of the system than known midspan adapters. Balance and symmetry inherent in a structured cable can be maintained by a termination network connecting center taps of a transformer and the spare pairs of both the incoming and outgoing cables to a common point. The adapter can provide power through unused wires (known as spare pair power) or by combining power with data signals (known as phantom feed). A common mode choke is included in the power feed to prevent noise currents from flowing through the power supply connections to earth ground, helping to minimize radiated noise.

Abstract: Embodiments related to line testing are described and depicted.

Abstract: A communication apparatus that includes: an operation unit; a line connection unit that operates in response to the operation of the operation unit; a number input unit; a dial signal transmitting unit that transmits a dial signal corresponding to a telephone number inputted by the number input unit; an operation detection unit that detects the operation of the operation unit; a measuring unit that measures a predetermined time when the operation of the operating unit is detected; and a number memory that stores the telephone number inputted by the number input unit before the measuring of the predetermined time by the measuring unit ends. A standby unit suspends a transmission of the dial signal corresponding to the telephone number stored in the number memory to the line until the measuring of the predetermined time by the measuring unit ends.

Abstract: A method and a device are provided for data processing, including the steps of transmitting a first signal from a first instance to a second instance and sending a second signal from a third instance to the first instance, wherein the second signal corresponds at least partially to the first signal as received at the third instance.

Abstract: The present invention is a new solution of line and relay in an analog subscriber board, which has a less number of relays and can decrease the cost and save the space while realizing the basic functions in a voice network. The technical solution of the invention provides each subscriber with two relays to connect the subscriber line interface circuit, the subscriber line, the ring bus and the test bus, realizing the basic functions relevant to the talking, such as talking, ringing, etc. In order to add the auxiliary functions such as the testing function and the monitoring function, the subscriber lines are grouped, and at least one relay is supplemented in a subscriber group, the subscriber group relays together with above two subscriber relays will be used to connect the subscriber line interface circuit, the subscriber line, the ring bus and the test bus to perform the basic functions relevant to talking and the auxiliary functions such as testing, monitoring, etc.

Abstract: A device includes a facsimile circuit, a voltage detector, an open-circuit voltage detector, and a telephone status monitoring unit. If a first voltage difference is less than a predetermined voltage difference, the monitoring unit judges that the public line is released if a second voltage difference is less than the predetermined difference, and that the public line is closed if the second difference is not less than the predetermined difference. If, when the facsimile circuit has released the public line, the first difference is not less than the predetermined difference, the monitoring unit judges that the public line is released if the second difference is less than the predetermined difference or if the detected line voltage equals the open-circuit voltage, and that the public line is closed if the second difference is not less than the predetermined difference and if the detected line voltage is different from the open-circuit voltage.

Abstract: A splitter unit including a chassis containing splitter cards. The splitter unit includes a central processing unit mounting location. The splitter unit also includes test access devices that are inactive when the central processing unit mounting location is vacant. The splitter unit is configured such that the splitter cards provide passive signal splitting even when the central processing unit mounting location is vacant.

Abstract: In a network device, a connector module comprises a network connector coupled to the connector module in a configuration that transfers power and communication signals and an application connector that comprises serial media independent interface (SMII) pins and power pins. A Power-over-Ethernet (PoE) circuit is coupled between the network connector and the application connector.

Abstract: Methods and apparatus for communicating include a first device coupled to a second device with a bi-directional data line and a clock line. Frames of data are serially communicated between the first and second devices on the data line. Each frame is synchronized with a clock signal carried by the clock line. Each frame has a portion allocated to data communicated from the first device to the second device and another portion allocated to data communicated from the second device to the first device.

Abstract: A modem includes modem circuitry and modem software that is executed by a processor. When the modem circuitry detects that the modem software is nonfunctional, it enters an on-hook state to prevent blocking of a coupled telephone line. A nonfunctional state of the modem software is detected when the modem software ceases to interact with the modem circuitry in an expected manner. In a first operation, the nonfunctional state is determined when the modem software does not reset a count down timer in the modem circuitry before the count down timer reaches a termination value. In a second operation, the nonfunctional state is determined when the modem software does not access the modem circuitry before the count down timer reaches the termination value. In a third operation, the nonfunctional state is determined when the modem software ceases writing transmit data to DMA memory.

Abstract: Encoding of a dual mode digital signal for transfer using a dual mode super source follower circuit to drive the signal across a pulse transformer is presented. The dual mode signal comprises data in one mode and power/control in the other mode. In the power/control mode the magnitude of the signal pulses are greater than the magnitude of the data pulses. Thus, the current sinking deficiencies of the super source follower may introduce waveform irregularities when transitioning from the high of the power pulse to the high of the data pulse. An encoding method described herein uses a return to zero scheme to avoid such waveform irregularities during power to data transitions.

Abstract: A method and apparatus detects a ground fault on a span-powered telecommunication wireline within a plurality of span-powered wireline segments, to respective ones of which DSL-Cs are coupled, so that a ground fault may be detected when power is delivered by the DSL-C over a respective wireline segment to a respective downstream functional RT. A respective DSL-C measures a first voltage across a first sense resistor representative of current flowing in a first portion of its wireline segment to the RT, and also measures a second voltage across a second sense resistor representative of current flowing in a second portion of the wireline segment from the RT. In response to a difference in the first and second voltages an output representative of a ground fault in that wireline segment is generated.

Abstract: Methods and apparatus for coupling outgoing analog audio signals to a subscriber line are described. A subscriber line interface circuit apparatus couples an outgoing audio signal to the subscriber line through a common base isolation stage. In one embodiment, linefeed driver control signals for controlling battery feed to the subscriber line are received on the same signal lines as the outgoing audio signal. In various embodiments, the common base isolation stage comprises a plurality of bipolar junction transistors coupled in a common base configuration or a plurality of field effect transistors coupled in a common gate configuration.

Abstract: While the amplification factor of an external amplifier is increased to raise the minimum volume level, synthesized speech of text data is generated as PCM data. When the PCM data is output for each frame (63 ms), the voltage of a battery power supply is detected and different ATT values (attenuation ratios) are set in accordance with threshold values (Level 1˜4) corresponding to the detected voltage. The lower the power supply voltage, the larger the attenuation ratios. The PCM data is attenuated by such an attenuation ratio to reduce a load to the battery power supply. Even though the battery power supply is exhausted to some extent, no power-down due to an instantaneous increase in power load occurs, with the result that a high-level part of a series of speech data items is output at an adequate volume level that makes a low-level part thereof easy to hear.

Abstract: A method and transmitter unit in a multi-tone, multi-line based transmission system, such as a digital subscriber line system, for determining a Power Spectral Density (PSD) of a plurality of users over a physical channel for at least one tone. Each of the users has a minimum required data rate and a maximum allowed power. A Power Minimization Problem (PMP) is formulated mathematically, introducing Lagrangian multipliers, and by utilizing a dual decomposition approach for the objective function of the PMP in order to solve the PMP on a per-tone basis.

Abstract: An interruption device arranged in a communication line including first and second cables in series, each including a first group of wires for the transmission of computer data and a second group of wires independent of the computer data, includes: a box provided with first and second input/output sockets with which the first and second cables, respectively, are connected; interrupters each connected between the first and second input/output sockets inside the box and actuable from outside the box, these interrupters being associated respectively with the wires of the first group; and transmission elements not including an interrupter and each connected between the first and second input/output sockets inside the box, these transmission elements being associated respectively with the wires of the second group. In a variant, the second input/output socket is replaced by two sockets associated with the interrupters and the transmission elements, respectively.

Abstract: A 7th order splitter for replacing the known 9th order splitter of an ISDN/POTS telecommunication system and reducing thereby the space occupied on the board as well as the cost. The 7th order splitter comprising, between line terminals (Line+, Line?) and POTS/ISDN terminals, the cascade connection of a LC filter cell (L21a, L12b, C21) and several elliptical filter cells (L22a, L22b, C22, C24, C25; L23a, L23b, C23, C26, C27). One or more of these filter cells is associated with a damped series resonance circuit comprising a capacitor (C21; C22; C23) series coupled with an RL circuit (R21, L24; R22, L25; R23, L26) between two winding (L21a, L21b; L22a, L22b; L23a, L23b) of a symmetrical coil of the associated filter cell. Each RL circuit is constituted by the parallel coupling of a resistor (R21; R22; R23) and a coil (L24; L25; L26).

Abstract: A subscriber line interface circuit apparatus includes a linefeed circuit and a subscriber line control circuit (SLCC). In an embodiment, the linefeed circuit includes a signal conversion circuit having cross-coupled first and second MOSFETs for providing a differential mode signal and a common mode signal in response to at least a tip signal and a ring signal from the subscriber loop. The linefeed circuit includes a tip control circuit and a ring control circuit, each having two or more MOSFETs. In an embodiment, the SLCC is provided in a single integrated circuit chip and is coupled to the linefeed circuit which isolates the SLCC from the tip or ring signals. The SLCC includes a first and a second differential mode inputs for receiving the differential mode signal, and a common-mode input for receiving the common-mode signal.

Abstract: Analog HPNA hub including at least one group of coils, the coils inducing HPNA signals there between, a plurality of filters, each of the filters coupled with a respective one of the coils and further coupled, via respective telephone wiring, with at least a respective HPNA node, wherein each of the filters enables transmission of HPNA data signals there through, and wherein each of the filters prevents transmission of conventional telephony signals there through.

Abstract: A system and method for delivering digital subscriber line (DSL) service to a subscriber from a remote terminal of a telephone network. Included is a first route for delivering a telephone signal to the subscriber, and a second route for passing the telephone signal through a DSL system before delivering the signal to the subscriber. A disrupter is then used to selectively activate either the first or second route.

Abstract: A line interface circuit with line side cancellation of a communication device is described herein. In one embodiment, a communication device includes a line interface circuit for interfacing a communication line. The line interface circuit includes a driver for driving multiple transmitting signals onto the communication line over multiple transmitting frequency bands. The line interface circuit further includes multiple transmitting filters each corresponding to one of the transmitting frequency bands. Other methods and apparatuses are also described.

Abstract: The invention concerns a method and device for processing echo between at least two communication devices in order to attenuate, in a picked-up signal of a communication device comprising at least one microphone, the components of the signal broadcasted by at least one other communication device comprising at least one loudspeaker, characterised in that the echo processing device comprises: means for receiving, by means of a connection with at least one other device, information representing at least one broadcasted signal of at least one other communication device, means for modifying the picked-up signal of the communication device according to information representing the broadcasted signal and information representing the coupling separating a loudspeaker of the said at least one other communication device from the microphone of the communication device.

Abstract: A multi-dwelling unit (MDU) module is configured for providing telephony communicating services and non-telephony services. The MDU module includes a motherboard and a plurality of service units connected to the motherboard. Each one of said service units and the motherboard are jointly configured for providing non-telephony service and telephony service to a plurality of service subscribers. The motherboard is configured for providing overload power management to limit power consumption associated with said telephony services during an overload condition and for providing lifeline power management to limit power consumption associated with said non-telephony services during a power outage condition. The MDU module optionally includes lightning primary surge protection blocks configured for being connected to the service units.

Abstract: Splitter wall plates for digital subscriber line (DSL) communication systems and methods to use the same are disclosed. An example apparatus comprises a splitter to separate a digital subscriber line (DSL) signal from a plain old telephone signal (POTS) signal, and a switch to selectively couple a VoIP signal received via a first jack or the POTS signal to a second jack.

Abstract: As part of a system and method for transmitting a signaling tone over a packet switched data (or other communication) network, an audio encoder may have a speech encoding unit and a tone distorter. The tone distorter may distort one or more components of a signaling tone within an audio signal and the speech encoding unit may encode speech and the distorted signaling tone within the audio signal. A control signal may be sent to a tone generator to reproduce the distorted tone.

Abstract: A test system and method for performing DSL assessments of a telephone line along a prescribed test path is disclosed. The disclosed test system and method includes a loop diagnostic test unit adapted for testing said telephone line using narrow-band and mid-band frequency test signals; a test system controller and a test system server to provide the DSL assessments to a user via an appropriate interface. In addition, the disclosed analysis methods utilize primary line condition information, secondary line condition information, historical line information, together with real-time measurements and external data inputs to perform line imbalance analysis, fault identification analysis, trend analysis, and jurisdictional analysis all of which have relevance to quality, performance and assurance of DSL service through the telephone line.

Abstract: An enclosure used with a system for delivering broadband service, including standard telephone service and telephone/DSL service, to a subscriber. The system includes a pair gain system, a cross-connect system, and a service distribution system. The enclosure is a retro-fit enclosure that incorporates the service distribution system into an existing cross-connect enclosure in a cost-effective and aesthetic manner. The service distribution system is operably located such that the standard telephone service and telephone/DSL service are routed from the service distribution system to the subscriber without being routed through the cross-connect system. The service distribution systems include terminating modules and switching modules. In some embodiments, the switching modules include protector plugs that protect the system from over-voltages and/or over-currents, and provides upstream and downstream diagnostic testing.

Abstract: A subscriber line interface circuit apparatus includes tip/ring sense circuitry generating a tip sense signal and a ring sense signal from three sensed currents, wherein the tip sense signal and the ring sense signal correspond to subscriber loop tip and ring currents, respectively. In one embodiment, the tip/ring sense circuitry includes a current mirror generating first and second mirrored sense currents from a first sense current proportional to a battery feed node voltage of a subscriber loop. Current differencing circuitry provides the tip sense signal from a difference between the first mirrored sense current and a second sense current associated with a tip line of the subscriber loop. The current differencing circuitry provides the ring sense signal from a difference between the second mirrored sense current and a third sense current associated with a ring line of the subscriber loop.

Abstract: The communication terminal device includes a handset, a central controller, a telephone network adaptor unit for converting analog signals transmitted/received between telecommunication network and the communication terminal device into digital signals, an interface unit physically isolating the central controller from the telephone network adaptor unit, and transmitting/receiving the converted digital signals between the central controller and the telephone network adaptor unit, and a telephone circuit unit which transmits the voice signals generated by processing the digital signals received from the telephone network adaptor unit to a handset through the interface unit and transmits the digital signals generated by processing the voice signals received from the handset to the telephone network adaptor unit through the interface unit.

Abstract: It is an object of the invention to provide a communication apparatus, a communication system and a communication method enabling efficient transmission in accordance with a situation of a wired transmission line and capable of reducing an influence by a radiation power of the transmission line. The communication apparatus of the invention executes wired transmission using a plurality of sub carriers and includes a transmission signal generator for generating a transmission signal, and a transmission signal controller for controlling a transmission power of the transmission signal generated by the transmission signal generator based on a radiation power in a transmission line in correspondence with a frequency of the sub carrier, and a transmitter for transmitting the transmission signal the transmission power of which is controlled by the transmission signal controller via the transmission line.

Abstract: Systems and methods are provided for passing through features from alternative network devices, such as cellular telephones, to plain old telephone system (POTS) devices. In a broad sense, the system includes an interface that bridges the alternative network devices to the POTS devices. The interface is configured to convey feature data contained within signaling data generated by the alternative network devices and pass the feature data through to the connected POTS devices. If the feature data is incompatible with the connected POTS devices, the interface is further configured to determine a compatible protocol for the connected POTS devices and translate the feature data into the compatible protocol.

Abstract: A second output transmission signal (“TX2”) added to a line driver is a scaled version of the main output transmission signal (“TX1”). TX2 is scaled from TX1 by a variable scale factor K. An adaptive hybrid circuit subtracts TX1 and TX2 from a line signal carrying both a line transmission signal and a line received signal (“RX”). A programmable impedance Ztune is coupled between the TX2 output of the line driver and the RX output of the adaptive hybrid circuit. A transmission echo in the output RX signal is measured. K and Ztune are then adaptively tuned to minimize the transmission echo. The hybrid in this case becomes a 4-port network, one port specifically added to adaptively cancel the transmission echo in the RX output of the adaptive hybrid circuit. Alternatively, the hybrid may be a 3-port hybrid including variable impedances to cancel the line transmission signal.

Abstract: A protection method and system for equipment in a network element receives a protection request for an equipment item. A priority of the request and a priority of the equipment item is evaluated relative to all other outstanding protection requests for equipment items in a protection group with the equipment item. A highest priority protection request for a highest priority equipment item is performed.

Abstract: This disclosure relates to varying load and modulation applied to each of multiple frequency subchannels based on anticipated attenuation experienced by those subchannels. Communicating data includes identifying a static component of a transmission medium for wideband communications having at least two subchannels determining a function of noise is attenuation versus frequency for the static component selecting wideband modulation schemes for the subchannels based on the function determined and communicating a data signal over the subchannels. The transmission medium includes a medium other than a copper telephone wire between and including a carrier facility and a termination of the copper telephone wire at an access point at a user premise and copper telephone wire in a cable riser in multitenant units and multi-dwelling buildings. Independent demodulation functions may be applied to at least two of the subchannels.

Abstract: The present disclosure provides for the sensing and detection of potential ground faults, and location of faulty ports. Circuitry is provided that utilizes the isolation resistor provided in the PSE. The present disclosure provides for temporarily breaking isolation to help improve the detection process disclosed herein.

Abstract: An analog front end. The analog front end comprises a converter configured to convert a differential input signal to a single-ended input signal, and convert a single-ended output signal to a differential output signal. And a transformer configured to couple the differential input signal from a twisted pair telephone line to the converter, and couple the differential output signal from the converter to the twisted pair telephone line.

Abstract: A second output transmission signal (“TX2”) added to a line driver is a scaled version of the main output transmission signal (“TX1”). TX2 is scaled from TX1 by a variable scale factor K. An adaptive hybrid circuit subtracts TX1 and TX2 from a line signal carrying both a line transmission signal and a line received signal (“RX”). A programmable impedance Ztune is coupled between the TX2 output of the line driver and the RX output of the adaptive hybrid circuit. A transmission echo in the output RX signal is measured. K and Ztune are then adaptively tuned to minimize the transmission echo. The hybrid in this case becomes a 4-port network, one port specifically added to adaptively cancel the transmission echo in the RX output of the adaptive hybrid circuit. Alternatively, the hybrid may be a 3-port hybrid including variable impedances to cancel the line transmission signal.

Abstract: An internet protocol telephone includes a substrate having an input and an output that are capable of being connected to the internet protocol (IP) network. A relay is disposed on the substrate and is connected between the input and the output of the substrate. The relay includes first and second native FETs that have a threshold voltage of approximately zero volts. Therefore, the relay is nominally turned-on, even when little or no voltage (or power) is applied to the IP telephone substrate, as during the discovery mode of IP telephone operation. During discovery mode, The IP phone is configured to be responsive to extended link pulses and block data packets that are associated with legacy devices. Data packets have a higher signal duration and are more continuous than extended link pulses. The IP phone includes a switchable ground that is connected to the gates of the native devices, and is controlled by a rectifier and filter circuit that are connected to the substrate input.

Abstract: Using a network in which one master station modem 105 and multiple slave station modem 106, 107, 108 are physically connected by rudder connection or bus connection with a telecommunication line 121, the measurement result of the S/N ratio between the master station and slave stations is once collected in the master station at the initialization stage, pairs of the modulation method, by which all modems can demodulate at high probability, and transmission voltage are calculated based on this data, and the calculation is transmitted to all slave stations; and at a normal transmission stage, information regarding the coordination and control of the network is transmitted in accordance with this setting. Thus, one-to-multi communication is realized, guaranteeing an access right.

Abstract: A digital subscriber line communicating system having a central office and a remote terminal connected through a telephone line, the transmitting side comprising a sliding window transmitting unit for transmitting DMT symbols according to the sliding window through the telephone line to the receiving side, and the receiving side comprising a sliding window receiving unit for receiving DMT symbols according to the sliding window from the transmitting side, the sliding window indicating the phase of cross-talk condition due to a TCM-ISDN transmission at the receiving side, whereby TCM cross-talk can be reduced without largely departing from the standard system.

Abstract: A termination device for a telephone line of a wire based telephone system, said termination device (30) comprising: a high pass filter (39) for separating signals within a frequency band used by a high-speed modem (13) for data transmission; and impedance means (53) connected to the high-pass filter (39), wherein said impedance means (53) has an impedance which matches the impedance of the telephone line in the frequency band used by the high-speed modem (13).

Abstract: The present integrated DSLAM to POTS splitter connector comprises a first set of wires each having a first end terminating in a first 50-pin connector for connecting to the DSLAM and second end terminating in a 64-pin connector for connecting to a first POTS splitter, one of the wires terminates in a first DPM; a second set of wires each having a first end terminating in a second 50-pin connector for connecting to the DSLAM, a second end terminating in a 64-pin connector for connecting to a second POTS splitter, one of the wires terminates in the first DPM and another in a second DPM; and a third set of wires each having a first end terminating in a third 50-pin connector for connecting to the DSLAM, a second end terminating in a 64-pin connector for connecting to a third POTS splitter, one of the wires terminates in second DPM.

Abstract: An impedance blocking filter circuit is provided for use in telecommunication systems for interconnecting between incoming telephone lines and customer's terminal equipment so as to unconditionally block impedances above 20 KHz a desired frequency range due to the customer's terminal equipment from an ADSL a DSL network unit and/or home networking interface unit. The filter circuit includes first, second, and third inductors connected in series between a first input terminal and a first common point. A first resistor has its one end connected also to the first common point and its other end connected to a first output terminal. Fourth, fifth and sixth inductors are connected in series between a second input terminal and a second common point. A second resistor has its one end also connected to the second common point and its other end connected to a second output terminal. A capacitor has its ends connected across the first and second common points.