Abstract: A signal line, which branches into four more from a connecting line on the input side via a branch point and has the branch signal lines including ?/4 transmission lines at their parts, and FETs respectively connected in shunt with the branch signal lines between connecting points on the output terminal sides as viewed from the ?/4 transmission lines provided in the branch signal lines and ground ends are provided on a semiconductor substrate. Connecting points of the FETs at the two branch signal lines are disposed with being spaced such a distance that isolation corresponding to the frequency of an RF signal reaches more than equal to 25 dB and less than or equal to 35 dB at the ends of these branch signal lines.

Abstract: A high performance single-pole-double-throw (SPDT) Transmitter/Receiver (T/R) FET switch utilizes a plurality of multi-gate FETs in series to realize low insertion loss, low harmonic distortion and high power handling capabilities. The SPDT switch consists of an antenna port, a transmitter branch coupled to a transmitter port through a plurality of multi-gate FETs in series and a receiver branch coupled to a receiver port through a plurality of multi-gate FETs in series. When a high power signal passes from the transmitter port to the antenna port through the transmitter branch, the receiver branch is required to be shut off electrically to prevent the high power signal from leaking to receiver port. This leakage can degrade the isolation of the switch and cause harmonic distortion. Furthermore, the transmitter branch is required to provide a resistance as small as possible to reduce the power loss when it passes through the transmitter branch to the antenna port.

Abstract: In a quadrature hybrid circuit which has first and second two-port circuits 11 and 12 inserted between I/O ports P1 and P2 and between I/O ports P4 and P3, respectively, and third and fourth two-port circuits inserted between I/O ports P1 and P4 and between I/O ports P2 and P3, respectively, and which is configured so that under the condition that the I/O ports P1 to P4 are matched, a high-frequency signal fed via the I/O port P1 is divided between the I/O ports P2 and P3 and the divided two signals are output 90° out of phase with each other but no signal is provided to the I/O ports P4, there are provided SPST switches 7 and 8 responsive to external control to control electromagnetic connections or coupling across a plane of symmetry 5 of the quadrature hybrid circuit passing through intermediate points of symmetry 23 and 24 of the third and fourth two-port circuits 21 and 22.

Abstract: A crossbar switch comprises a number of crossing points at which controllable switch elements are arranged, via which an input signal supplied to a row can be interconnected to a column intersecting this row at this crossing point when an interconnection signal is supplied to the respective setting parameter via a control input. The controllable switch elements comprise amplifier elements whose amplifier inputs are connected with the rows and whose amplifier outputs are connected with the columns. The amplifier elements are wired such that they only consume electrical energy when the interconnection signal is supplied to the respective crossing point.

Abstract: Equivalent circuits and a simulation method for simulating an RF switch are disclosed. The equivalent circuits are a first equivalent circuit and a second equivalent circuit, and are formed by resistors, capacitors, and inductors. The method includes using the first equivalent circuit to simulate the switch at a turned-off state and using the second equivalent circuit to simulate the switch at a turned-on state.

Abstract: A multi-band antenna switch circuit including a diplexer connected to an antenna terminal for demultiplexing signals of different passing bands, a first and a second switch circuit for switching a high frequency signal and a low frequency signal demultiplexed by the diplexer to a plurality of transmission/reception terminals, a first and a second low pass filter connected to a transmission path between the diplexer and the transmission terminal or between the first and the second switch circuit and the transmission terminal, and a notch filter provided between the diplexer and the first switch circuit or between the diplexer and the second switch circuit.

Abstract: Quad band antenna interface modules include a diplexer that is configured to connect to an antenna port, a switching core that is connected to the diplexer, and filters that are connected to the switching core and are configured to provide transmit and receive ports for four frequency bands. At least one matching network port is connected between the switching core and at least one of the filters and is configured to connect a matching network thereto. Three filters and three matching network ports may be provided. A switched impedance matching network and/or a singly compensated dual diode switch also may be provided.

Abstract: A circuit for guiding electromagnetic waves includes a substrate for supporting components of the circuit. The circuit includes a control device which includes a first conductive element on the substrate for connection to a first component of the circuit and a second conductive element on the substrate for connection to a second component. The control device is made up of a variable impedance switching material on the substrate which exhibits a bi-stable phase behavior. The compound has a variable impedance between a first impedance state value and a second impedance state value which can be varied by application of energy thereto to thereby affect the amplitude or phase delay of electromagnetic waves through the circuit.

Abstract: An RF signal divider/combiner is provided for dividing a supplied RF signal to any number of up to N output ports. A switchable impedance matching network is provided to impedance match the divider according to the number of output ports connected.

Abstract: A laminated high-frequency switch module for selecting either a transmission circuit or a reception circuit of each of transmission/reception systems by switching, comprising a demultiplexer for demultiplexing signals of the transmission/reception systems, high-frequency switch circuits for selecting either the signal path of a reception signal from the demultiplexer to the reception circuit or the signal path of a transmission signal from the transmission circuit to the demultiplexer, and circuit for measuring the power of the transmission signal from the transmission circuit, characterized in that the laminate is composed of dielectric layers having electrode patterns, and the demultiplexer, the high-frequency switch circuits, and the power measuring circuit are constituted of electrode patterns in the laminate.

Abstract: A high-frequency switch has a first transmission-reception switching circuit for selectively switching between the signal transfer between an antenna terminal and a first transmitting-circuit terminal and the signal transfer between the antenna terminal and a first receiving-circuit terminal; a second transmission-reception switching circuit for selectively switching between the signal transfer between the antenna terminal and a second transmitting-circuit terminal and the signal transfer between the antenna terminal and a second receiving-circuit terminal; a first diplexer disposed between the antenna terminal and the first transmission-reception switching circuit and between the antenna terminal and the second transmission-reception switching circuit; and a second diplexer connected to the second receiving-circuit terminal to selectively switch the signal transfer between the second receiving-circuit terminal and a third receiving-circuit terminal and the signal transfer between the second receiving-circuit

Abstract: A plurality of first transistors are connected in series between the first terminal and the second terminal. A plurality of second transistors are connected in series between the first terminal and the third terminal. One end of a resistor is connected to the first terminal, and the other end of the resistor is grounded. Either the first transistor or the second transistor is controlled to be ON. A resistance value of the resistor is set at such a value that a difference between a gate voltage of the first or second transistor being ON and a pinch-off voltage of the first or second transistor being ON is set greater than the amplitude of the potential of the first terminal which varies upon reception of a signal flowing to the first terminal. In this structure, the first and second transistors are appropriately operated regardless of signal frequency.

Abstract: A high frequency switch is provided with an input terminal, an output terminal, a first diode, a second diode, a first resistor, a third diode and a second resistor. The first diode is provided in a signal line, which connects the input terminal to the output terminal. The first diode has an input end and an output end. The second diode has one end, which is connected to the input end side of the first diode. The first resistor is provided in a terminated line, which is connected to another end of the second diode. The third diode has one end, which is connected to the output end side of the first diode. The second resistor is provided in a terminated line, which is connected to another end of the third diode.

Abstract: Disclosed herein is an antenna switching module having an amplification function, in which the power amplification of a transmission signal is performed together with the switching of transmission/reception signals to an antenna, using a basic antenna switching construction, thus reducing costs of mobile terminals and miniaturizing the mobile terminals. The antenna switching module has an amplifier, a low pass filter, a transmission line, and a switching diode. The amplifier is implemented using at least one active element and a bias circuit to intercept or amplify a transmission signal applied through a transmission terminal, wherein the bias circuit drives the active element to be turned on/off in response to a control signal and determines an amplification factor. The low pass filter is disposed between the amplifier and the antenna terminal to eliminate harmonic frequency components included an output signal of the amplifier.

Abstract: An improved radio frequency (RF) switch circuit is disclosed. The RF switch is typically used in a communication system having one or more transmission paths and one or more reception paths. The RF switch has a first set of diodes connected in parallel among themselves, and a second set of diodes connected in parallel among themselves. Each diode of the second set is coupled with at least one predetermined diode in the first set in a parallel manner by sharing a connection node that is coupled further with at least one antenna. A transmitter is coupled to the first set of diodes and the receiver is separately coupled to the second set of diodes, wherein either one of the first set of diodes or the second set of diodes are activated to establish one path while cutting off all other paths at the same time.

Abstract: A multiband transformation stage (14) comprising a common first signal port (20), a common second signal port (26) and a signal path (50) coupled between the first signal port (20) and the second signal port (26) is described. The signal path (50) is switchable between a first state with a first quarter-wavelength transformer characteristic for a first frequency band, a second state with a second quarter-wavelength transformer characteristic for a second frequency band and a third state with a transmission characteristic. The invention also relates to a multiband switching device comprising the multiband transformation stage (14) in combination with a low-power switching stage (16).

Abstract: A micro electromechanical switchable capacitor is disclosed, comprising a substrate, a bottom electrode, a dielectric layer deposited on at least part of said bottom electrode, a conductive floating electrode deposited on at least part of said dielectric layer, an armature positioned proximate to the floating electrode and a first actuation area in order to stabilize the down state position of the armature. The device may furthermore comprise a second actuation area. The present invention provides shunt switches and series switches with actuation in zones attached to the floating electrode area or with relay actuation.

Abstract: A high-frequency switch having two input terminals and two output terminals of which a broad pass band is required has (i) a circuit board that has two input electrodes along one side and two output electrodes along another side, and (ii) four PIN diodes mounted on this circuit board. Each side of the quadrangle made by connecting the input electrodes and the output electrodes is not parallel to the corresponding side of the quadrangle made by connecting electrodes for mounting the PIN diodes. Each side and the corresponding side form an angle other than 180°. This structure can provide a high-frequency switch capable of reducing a transmission loss in the paths and facilitating impedance matching.

Abstract: A switch selectively provides one of a first input signal at a first frequency and a second input signal at a second frequency to an output terminal with low insertion loss and high isolation between the first and second input signals. The first input signal is received at a first input terminal and the second input signal is received at a second input terminal. A switching element electrically connects the first input terminal and the output terminal to provide the first input signal to the output terminal in a first state and isolates the first input terminal from the output terminal in a second state. A bias line is electrically connected to provide a control signal to the switching element to select between the first state and the second state. An AC coupled transmission line is electrically connected to the second input terminal and electrically connected between the switching element and the output terminal.

Abstract: A switch matrix including a plurality of microstrip pairs arranged to form a grid and switches to couple the microstrip pairs where they cross. Each microstrip pair includes a first microstrip and a second microstrip for passing signals. The signals on the first and second microstrips are such that the electromagnetic forces produced by each one are canceled out by the other. By canceling out the electromagnetic forces, undesirable coupling between microstrips that cross and between microstrips and the substrate are minimized, thereby allowing inexpensive substrates such as silicon to be used.

Abstract: A high-frequency compound switch module of this invention has a first communication system comprising a switch unit for switching connection of a signal from an antenna to one of a transmission circuit and a reception circuit of the first communication system based on a signal from a control terminal, a filter provided on a first reception circuit side, for filtering out a first reception signal, and a first phase shift line provided between the filter and the switch unit, and a second communication system comprising a second phase shift line provided between the switch unit and the first phase shift line, and a branching filter provided in series to the second phase shift line for branching a signal from the second phase shift line into a second transmission signal and a second reception signal. The switch module is capable of performing at least a receiving process of the first communication system while performing transmission/reception with the second communication system.

Abstract: An antenna switch including a transmit connection for inputting a radio frequency signal, an antenna connection for connection to an antenna for transmitting the radio frequency signal, and a signal path between transmit connection and the antenna connection including at least one transmit transistor controllable to connect selectively the transmit connection to the antenna connection so as to transfer the radio frequency signal from the transmit connection to the antenna connection wherein the transmit transistor is arranged so as to provide a stage of amplification to the radio frequency signal.

Abstract: Systems and techniques are disclosed relating to a radio with duplexer bypass capability. The radio includes an antenna, a duplexer, a receiver; and a switching circuit configured to switch the antenna between the duplexer and the receiver. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or the meaning of the claims.

Abstract: The coupler of the present invention includes a plurality of core members that are disposed between the semi-conductive ground jacket and neutral conductor of a standard URD MV cable. The core members are series wound by a transformer conductor, which forms a secondary winding that is coupled to the primary of a transformer, which provides impedance translation and/or isolation. The secondary of the transformer is coupled to a connector for communicating data signals through the coupler.

Abstract: The present invention provides a transceiver apparatus that permits miniaturization even when the antenna thereof is an unbalanced circuit and the transmitter circuit section and receiver circuit section thereof are balanced circuits. The transceiver apparatus is constituted comprising: a semiconductor integrated circuit device that mounts on the same semiconductor chip a balanced receiver circuit 41 for receiving a received signal as a differential input and balanced transmitter circuit 52 for outputting a transmitted signal as a differential output, and that has at least two terminals 71,72 connected to connecting nodes that connect the balanced receiver circuit 41 and the balanced transmitter circuit 52; first and second capacitors C2,C3 connected to the terminals 71, 72 respectively; an external inductor L1 connected to the first and second capacitors C2, C3; a band pass filter 2 and an antenna 1 coupled to the first capacitor C2; and a third capacitor C1 connected to the second capacitor C3.

Abstract: Briefly, in accordance with one embodiment of the invention, a combiner may include transmission lines to couple a receive port and a transmit port to an antenna at a common junction. Shunt admittance elements may be utilized at the transmit and the receive ports to isolate one of the transmit and the receive ports from the antenna by shunting the at least one of the transmit and the receive ports to a power supply potential such as a ground reference. During a transmit mode, the shunt admittance element at the receive port may shunt the receive port to the power supply potential, thereby isolating the receive port from the antenna. During a receive mode the shunt admittance element at the transmit port may shunt the transmit port to the power supply potential, thereby isolating the transmit port from the antenna.

Abstract: A filter assembly includes a transmission filter, a reception filter, a change-over switch, and phase circuits. The transmission filter has first and second ends electrically connected to a first antenna terminal and a transmission terminal, respectively. The reception filter has a first end electrically connected to a second antenna terminal via the change-over switch, and a second end electrically connected to a reception terminal. A main antenna is connected to the first antenna terminal, and a diversity antenna is connected to the second antenna terminal. The change-over switch performs switching control to connect the reception filter to one of the first and second antenna terminals. Thus, the filters utilize a fixed number of resonators regardless of switching control of the change-over switch, thereby achieving optimum filter characteristics.

Abstract: A circuit for guiding electromagnetic waves includes a substrate for supporting components of the circuit. The circuit includes a control device which includes a first conductive element on the substrate for connection to a first component of the circuit and a second conductive element on the substrate for connection to a second component. The control device is made up of a variable impedance switching material on the substrate which exhibits a bi-stable phase behavior. The compound has a variable impedance between a first impedance state value and a second impedance state value which can be varied by application of energy thereto to thereby affect the amplitude or phase delay of electromagnetic waves through the circuit.

Abstract: In a switching scheme mechanical MEMs switches are connected in parallel with solid state switches. This parallel MEMS/solid-state switch arrangement takes advantage of the fast switching speeds of the solid state switches as well advantage of the improved insertion loss and isolation characteristics of the MEMS switches. The solid-state switches only need to be energized during a ramp up/down period associated with the slower MEMs switch thus conserving power. As an additional advantage, using a solid-state switch in parallel with MEMs switches improves the transient spectrum of the system during switching operations.

Abstract: A transmission line adapter for high speed interface. A receiver receives input signals via a transmission line. An active termination circuit is selectively connected to the transmission line in parallel with the receiver according to a receive condition. A self-terminated driver circuit outputs a first voltage and a second voltage according to output data. A selective circuit for selectively connects the self-terminated driver circuit to the transmission line when output of the self-terminated driver circuit is a first voltage, and selectively connects the self-terminated driver circuit or the active termination circuit to the transmission line when the output is a second voltage.

Abstract: A PIN diode switching system is provided, particularly for the transmission stage of a mobile radio telephone, in which, when the PIN diode switching system is in a reverse-bias state, a PIN diode is isolated from its power supply via a high-impedance switch and is, thus, biased by its self-rectification to a radio-frequency voltage in order to suppress harmonic formation and radio-frequency attenuation.

Abstract: An arrangement for bypassing a low-noise amplifier (LNA), intended especially to be used in base stations of mobile networks. For the bypass, a receiver antenna filter (210) has a second output (OUT2) parallel with a first output (OUT1) connected to the LNA. The antenna filter is of the resonator type, and there is a conductive element for each of its outputs in the resonator cavity. Selection between the LNA out-put signal and signal coming direct from the antenna filter is made by a changeover switch (SW). The noise figure of the receiver front stage (220) will improve as the series switch on the signal path, which most degrades the noise figure, is removed between the filter and LNA, and isolation on the LNA bypass path increases.

Abstract: A high frequency module substrate device used in a high frequency module apparatus, which is adapted for switching pass-frequency characteristic of band-pass filter by switching and is adapted so that optimum band-pass filter characteristic is obtained in all pass-frequency bands, wherein a thin film capacitor element (18) is constituted between a base substrate (2) in which the uppermost layer is flattened with organic substrate being as core substrates (5), (6) to constitute a buildup formation surface (16) and a high frequency circuit unit (3) of lumped parameter design formed on the buildup formation surface in a laminated manner to carry out switching of load of parallel capacity with respect to a coupler (11) having frequency characteristic of ?/4 which has been caused to undergo distributed parameter design at the base substrate portion side of the thin film capacitor through switch means (4).

Abstract: The invention relates to a terminal for communication with data supports which function in a non-contact manner, comprising a transreceiver circuit with two resonant circuits with antenna and condenser for the emitting of two radio frequency fields of different carrier frequencies, whereby the common antenna (A) for both resonant circuits comprises a winding.

Abstract: A broadband multiple input, multiple output switch matrix. The switch matrix comprises multiple crosspoint switch element tiles. Each tile comprises RF MEMS switches disposed on a substrate to provide a crosspoint switching capability. The crosspoint switch element tiles are disposed in a flip-chip manner on the upper side of an RF substrate that provides RF connectivity between the various crosspoint switch element tiles. A bias line substrate disposed on the lower side of the RF substrate receives control signals for the crosspoint switch element tiles and routes the signals through the RF substrate using vias in the RF substrate.

Abstract: MEMS Device Having Contact and Standoff Bumps and Related Methods. According to one embodiment, a movable MEMS component suspended over a substrate is provided. The component can include a structural layer having a movable electrode separated from a substrate by a gap. The component can also include at least one standoff bump attached to the structural layer and extending into the gap for preventing contact of the movable electrode with conductive material when the component moves.

Abstract: A high-frequency switch comprises: a substrate; a main line electrode provided between two terminals; a stub line electrode with one end thereof connected to the side edge of the main line electrode and the other end thereof grounded; and a ground electrode provided adjacent to the stub line electrode in the width direction thereof; wherein the substrate has a semiconductor activation layer which extends to below the stub line electrode and the ground electrode between at least one side edge of the stub line electrode and the ground electrode; and wherein a gate electrode which extends in the longitudinal direction of the stub line electrode is provided on the semiconductor activation layer between the stub line electrode and the ground electrode, thereby forming an FET structure, thus providing a high-frequency switch and electronic device therewith, capable of using high frequencies, having reduced insertion loss, and high signal cut-off capabilities.

Abstract: A high frequency switch circuit device includes an FET to be a switching element on a semiconductor substrate. The FET includes an n-type well, a gate electrode, a source layer and a drain layer. An n-type well line to be connected to an n-type well layer to be a back gate is connected to a voltage supply node via an inductor. The flow of a high frequency signal between the voltage supply node and the n-type well layer is blocked by the inductor, and the flow of a high frequency signal in the vertical direction is blocked by a depletion layer extending between the n-type well and a p-type substrate region. Moreover, the flow of a high frequency signal in the horizontal direction is blocked by a trench separation insulative layer.

Abstract: A high-frequency switch has a first transmission-reception switching circuit for selectively switching between the signal transfer between an antenna terminal and a first transmitting-circuit terminal and the signal transfer between the antenna terminal and a first receiving-circuit terminal; a second transmission-reception switching circuit for selectively switching between the signal transfer between the antenna terminal and a second transmitting-circuit terminal and the signal transfer between the antenna terminal and a second receiving-circuit terminal; a first diplexer disposed between the antenna terminal and the first transmission-reception switching circuit and between the antenna terminal and the second transmission-reception switching circuit; and a second diplexer connected to the second receiving-circuit terminal to selectively switch the signal transfer between the second receiving-circuit terminal and a third receiving-circuit terminal and the signal transfer between the second receiving-circuit

Abstract: A radio frequency (RF) hybrid switch module includes an antenna duplexer integrated with a surface acoustic wave (SAW) filter used in a mobile communication device such as a cellular phone. The switch module handles a transmitted signal and received signal of different frequency bands. A parasitic inductance due to a mounting of the SAW filter is reduced, so that an attenuation characteristic at a low frequency of the SAW filter is improved.

Abstract: In order to provide a high frequency switch in which the setting range of the control voltage is expanded, the high frequency switch is constructed from a switch and a reference voltage generation circuit. The switch comprises first and second field effect transistors. In the first field effect transistor, the source electrode is connected to a signal input terminal, while the drain electrode is connected to a signal output terminal, and while the source electrode is connected to a control terminal. In the second field effect transistor, the source electrode is connected to the signal input terminal, while the drain electrode is connected to the signal output terminal, and while the gate electrode is connected to the control terminal.

Abstract: A multiband high-frequency switch that is mainly used for mobile phones, comprising a strip line formed of the series connection of first and second strip lines. A second transmitting port is connected to the connection point of the strip lines connected in series via a third diode, and a second control port is connected between the second transmitting port and the third diode. In addition, first and second receiving ports are connected to the receiving-side port of the high-frequency switch via a diplexer.

Abstract: A circuit is provided where impedance converters (41-48) are provided such that active components (P1 to P8) can be switched off without power from the other active components leaking away through those components which are switched off.

Abstract: In a high-frequency switching module for use mainly in a communications apparatus and a high-frequency apparatus equipped with the same, the high-frequency switching module has a group of high-frequency terminals provided on the mounting side surface of a multi-layer assembly of which the lateral sides are formed as no-electrode provided sides excluding the high-frequency terminals. Thus, the high-frequency switching module and the high-frequency apparatus equipped with the same are less susceptible to the external effect.

Abstract: A circuit for guiding electromagnetic waves includes a substrate for supporting components of the circuit. The circuit includes a control device which includes a first conductive element on the substrate for connection to a first component of the circuit and a second conductive element on the substrate for connection to a second component. The control device is made up of a variable impedance switching material on the substrate which exhibits a bi-stable phase behavior. The compound has a variable impedance between a first impedance state value and a second impedance state value which can be varied by application of energy thereto to thereby affect the amplitude or phase delay of electromagnetic waves through the circuit.

Abstract: Switchable path length coupler/dividers. Coupler/divider operation over multiple frequency bands is provided by using switchable path lengths. In one implementation, a Wilkinson-style device with switches to select different path lengths and therefore operating frequencies. In a rat-race style device, switches select races of different lengths, and therefore operating frequencies.

Abstract: A microelectromechanical system (MEMS) switch has a beam with a high-resonance frequency. The MEMS switch includes a substrate having an electrical contact and a hexsil beam coupled to the substrate in order to transfer electric signals between the beam and the contact when an actuating voltage is applied to the switch. A method of fabricating a MEMS switch includes forming a substrate having a contact and forming a beam. The method further includes attaching the beam to the substrate such that the beam is maneuverable into and out of contact with the substrate.

Abstract: A micromachine switch includes a driving part (12) for displacing a contact (11) on the basis of a control signal, a first control signal line (4) for applying the control signal to the driving part, and a first RF signal inhibiting part (3) connected to the first control signal line to inhibit, from passing therethrough, an RF signal flowing RF signal lines (1a, 1b). With this arrangement, an insertion loss of the micromachine switch can be reduced, and the RF characteristic of a circuit using the micromachine switch can be improved.

Abstract: A part of transmission signal is branched by a directional coupler, and split by a splitting circuit, so that the transmission signal can be outputted to the subscribers' terminal devices via branched output terminals. Latching relays disposed in signal paths to the branched output terminals from the splitting circuit can set the output/stop of the transmission signal to the terminal devices. A control circuit switches the connected/disconnected state of the relays in response to the command signal from the center apparatus. When an operation switch is turned on, all the relays are placed into the connected state. As a result, after the installation of the tap device, by operating the operation switch, the broadcasting signal can be distributed to the terminal devices before the command signal is received.

Abstract: A communication device (1) is described, comprising a powered transceiver (2), a line transceiver (3), an isolation circuit (4) comprising three capacitors Cb1, Cb2 and Cb3, which are coupled between the powered transceiver (2) and the line transceiver (3), and a control circuit (5) arranged for controlling the transport of power from the powered transceiver (2) to the line transceiver (3) and for accomplishing a bi-directional communication across the isolation circuit (4). The control circuit is a two-mode controlled circuit (5), arranged such that during a first mode said power is transported and a communication in one direction is performed, and that during the second mode the communication in the other direction is accomplished.