A bi-directional RF signal amplifier includes a RF input port and surge suppression circuitry downstream of the RF input port. First and second communications paths lead from the surge suppression circuitry to first and second RF output ports. The second communications path is considered non-interruptible and can support both downstream and upstream RF communications even in the absence of power being supplied to the RF signal amplifier. The surge suppression circuitry includes a data line connected to the RF input port. A first circuit path is electrically connected between the data line and ground. A gas discharge tube (GDT), within the first circuit path, acts as an open circuit when a voltage across the GDT is less than a predetermined value and acts as a short circuit when the voltage across the GDT exceeds the predetermined voltage. An electronic device is placed in series with the GDT within the first circuit path. The electronic device enables the second communications path of the RF signal amplifier to remain operable even if the GDT fails to a short circuit state due to a breakdown of the gases within the GDT.

A network element of a cable television (CATV) network, comprising an input for upstream signal transmission; one or more diplex filters (210, 212, 214) connectable to said input, the diplex filters (210, 212, 214) comprising bandpass filters for different upstream and downstream frequency bands; a plurality of components arranged to form an upstream signal path, wherein at least one of said components is an upstream amplifier (206c); means (216) for detecting a type of the diplex filter connected between said input and the upstream signal path; means (216) for determining a control signal for adjusting bias current of the upstream amplifier (206c), wherein the control signal is based on at least a type of the diplex filter; and means for adjusting the bias current of the upstream amplifier (206c) based on the control signal.

Systems and methods for implementing Soft-duplex functionality in an amplifier in a HFC network.

A circuit that includes a Darlington transistor pair having an input transistor and an output transistor configured to generate an output signal at an output node in response to an input signal received through an input node is disclosed. The circuit has a feedback coupling network coupled between the output node and the input node for feeding back to the input node a portion of an amplified version of the input signal that passes through the input transistor. The circuit further includes a bias feedback network that includes a bias transistor and a resistive network that consists of only resistive elements such that no inductors and no capacitors are provided within the bias feedback network.

The present invention discloses a low-noise amplifier having a characteristic of high linearity for multi-band. Embodiments of the present invention is to provide a low-noise amplifier (LNA), which realizes a balun function and a preamplifier function of mixer in the low-noise amplifier (LNA), and minimizes the factors reducing the linearity between the low-noise amplifier (LNA) and the mixer.

An amplifier system an amplified path and a bypass path for carrying an RF signal. A switch in the amplified system routes the RF signal through the amplified path in response to a normal condition in the amplifier system, and routes the RF signal through the bypass path in response to an abnormal condition in the amplifier system. The amplified path includes an amplified forward circuit and a return circuit. The amplified forward circuit has an amplifier, and the return circuit has a return amplifier and detection circuitry for providing power to the return amplifier. The detection circuitry provides power to the return amplifier in response to a normal condition in the return circuit, and removes power from the return amplifier in response to an abnormal condition in the return circuit.

A cable network system for bidirectionally communicating signals at an enhanced duplex frequency range, which may be between about 5 MHz and about 650 MHz. This system may include a first amplifier, which may be configured to condition an upstream signal proceeding from a subscriber premises to a headend, without necessarily conditioning a downstream signal proceeding from the headend to the subscriber premises, a second amplifier, which may be configured to condition the downstream signal without necessarily conditioning the upstream signal, and a shaping circuit, which may condition the upstream and downstream signals. This system also may simultaneously, or in an overlapping or offset manner, communicate signals at a full duplex frequency range without a diplex filter.

There is provided an amplifier device for a CATV network comprising a first amplifier element for upstream signals and a second amplifier element for downstream signals, wherein the first and second amplifier elements are disposed between first and second directional couplers. The combined isolation of the first and second directional couplers is greater than the sum of the gain of the first and second amplifier elements. The first directional coupler has one port attached to an input of the downstream amplification element and one port attached to an output of an upstream amplification element (38) and the second directional coupler has one port attached to an output of the downstream amplifier and one port attached to an input of the upstream amplifier.

There is provided fiber-coaxial amplifier device (10) comprising at least one output (14) and a test point (26) associated with the at least one output (14), wherein alternative first and second electrical paths (36, 38) are connectable to the at least one output (14), the first path (36) connectable to the at least one output (14) whilst bypassing the test point, the second path (38) connectable to both the at least one output (14) and the test point (26), and a relay (30) operable to connect one of the first path or the second path to the at least one output (14). The fiber-coaxial amplifier device (10) is configured for signals complying with Extended Spectrum DOCSIS.

There is provided an amplifier device comprising a first directional coupler (12: 30, 32) and a second directional coupler (14: 30, 32) connected together so as to create separate upstream (16) and downstream (18) paths in which amplifier means (24, 24) are located, wherein the first and second directional couplers (12, 14: 30, 32; 30, 32) are configured to have different signal loss characteristics, one of the directional couplers having low signal loss characteristics for upstream signals and the other directional coupler having low signal loss characteristics for downstream signals. The signal loss characteristics are preferably the coupling loss of each directional coupler (12, 14: 30, 32; 30, 32). The first and second directional couplers may each comprise a microstrip directional coupler (30; 30) connected to a ferrite directional coupler (50; 50).