US 6,639,779 B2 · Frequency selective transient voltage protector

Abstract

A frequency selective transient voltage protector (FSTVP) circuit that may be used in connection with a communication line over which POTS and DSL service may be simultaneously provided. The FSTVP circuit attenuates high frequency transient voltages that exceed a predetermined voltage level, while permitting low frequency, generally high voltage signals (e.g., ring signals) and high frequency, low voltage signals (e.g., DSL signals) to pass with little or no attenuation. The FSTVP circuit comprises a frequency selective network (that comprises a frequency discriminator and a voltage discriminator) connected to an overvoltage protection device that shunts any high frequency transient voltages thus protecting devices connected downstream along the communications line from damage. The frequency selective network is tuned to gate the overvoltage protection device when the frequency and voltage of a signal present on the communication line exceed predetermined values.

Claims46

Dependent claims

A frequency selective transient voltage protector connectable to a two-wire communications line upon which a signal having a voltage and a frequency may be present and comprising:

a frequency discriminator connectable across the communications line, said frequency discrimination having an output and a voltage at said output related to the frequency and voltage of the signal on the communications line;
a voltage discriminator connected to said output of said frequency discriminator, said voltage discriminator being in a conductive state and presenting a low impedance to said output of said frequency discriminator when a signal present on the communications line has a frequency equal to or exceeding a predetermined frequency and a voltage equal to or exceeding a first predetermined voltage, said voltage discriminator otherwise being in a nonconductive state and presenting a high impedance to said output of said frequency discriminator;
and
an overvoltage protection device connected to said voltage discriminator and connectable across the communications line, said overvoltage protection device being in a conductive state and presenting a low impedance to the signal present on the communications line when said voltage discriminator is in said conductive state, and being in a nonconductive state and presenting a high impedance to the signal present on the communications line when said voltage discriminator is in said nonconductive state.

1 more element

A frequency selective transient voltage protector connectable to a two-wire communications line upon which a signal having a voltage and a frequency may be present and comprising:

a DC overvoltage protection first stage connected between the two-wire communications line and earth ground;
and
a second stage connected to said first stage and comprising:
a frequency discriminator connectable across the communications line said frequency discriminator having an output and a voltage at said output related to the frequency and voltage of the signal on the said communications line;
a voltage discriminator connected to said output of said frequency discriminator, said voltage discriminator being in a conductive state and presenting a low impedance to said output of said frequency discriminator when a signal present on the communications line has a frequency equal to or exceeding a predetermined frequency and a voltage equal to or exceeding a first predetermined voltage, said voltage discriminator otherwise being in a nonconductive state and presenting a high impedance to said output of said frequency discriminator;
and
an overvoltage protection device connected to said voltage discriminator and connectable across the communications line, said overvoltage protection device being in a conductive state and presenting a low impedance to the signal present on the communications line when said voltage discriminator is in said conductive state, and being in a nonconductive state and presenting a high impedance to the signal present on the communications line when said voltage discriminator is in said nonconductive state.

4 more elements

A frequency selective transient voltage protector connectable to earth ground and to a two-wire communications line upon which a signal having a voltage and a frequency may be present and comprising:

a first frequency discriminator connectable between a first wire of the communications line and earth ground, said first frequency discriminator having an output and a voltage at said output related to the frequency and voltage of the signal on the communications line;
a first voltage discriminator connected to said output of said first frequency discriminator, said first voltage discriminator being in a conductive state and presenting a low impedance to said output of said first frequency discriminator when a signal present on the communications line has a frequency equal to or exceeding a predetermined frequency and a voltage equal to or exceeding a first predetermined voltage, said first voltage discriminator otherwise being in a nonconductive state and presenting a high impedance to said output of said first frequency discriminator;
a first overvoltage protection device connected to said first voltage discriminator and connectable between the first wire of the communications line and earth ground, said first overvoltage protection device being in a conductive state and presenting a low impedance to the signal present on the communications line when said first voltage discriminator is in said conductive state, and being in a nonconductive state and presenting a high impedance to the signal present on the communications line when said first voltage discriminator is in said nonconductive state;
a first DC overvoltage protection device connected to the first wire of the communications line and to said first overvoltage protection device and said first voltage discriminator, said first DC overvoltage protection device being in a conductive state and presenting a low impedance when the signal present on the communications line has a frequency below said predetermined frequency and a voltage equal to or exceeding a second predetermined voltage, said first DC overvoltage protection device otherwise being in a nonconductive state and presenting a high impedance to the signal present on the communications line;
a second frequency discriminator connectable between a second wire of the communications line and earth ground, said second frequency discriminator having an output and a voltage at said output related to the frequency and voltage of the signal on the communications line;
a second voltage discriminator connected to said output of said second frequency discriminator, said second voltage discriminator being in a conductive state and presenting a low impedance to said output of said second frequency discriminator when a signal present on the communications line has a frequency equal to or exceeding said predetermined frequency and a voltage equal to or exceeding said first predetermined voltage, said second voltage discriminator otherwise being in a nonconductive state and presenting a high impedance to said output of said second frequency discriminator;
a second overvoltage protection device connected to said second voltage discriminator and connectable between the second wire of the communications line and earth ground, said second overvoltage protection device being in a conductive state and presenting a low impedance to the signal present on the communications line when said second voltage discriminator is in said conductive state, and being in a nonconductive state and presenting a high impedance to the signal present on the communications line when said second voltage discriminator is in said nonconductive state;
and
a second DC overvoltage protection device connected to the second wire of the communications line and to said second overvoltage protection device and said second voltage discriminator, said second DC overvoltage protection device being in a conductive state and presenting a low impedance when the signal present on the communications line has a frequency below said predetermined frequency and a voltage equal to or exceeding a second predetermined voltage, said second DC overvoltage protection device otherwise being in a nonconductive state and presenting a high impedance to the signal present on the communications line.

6 more elements

A frequency selective transient voltage protector connectable to a two-wire communications line upon which a signal having a voltage and a frequency may be present and comprising:

a frequency discriminator connectable across the communications line, said frequency discriminator having an output and a voltage at said output related to the frequency and voltage of the signal on the communications line;
a voltage discriminator connected to said output of said frequency discriminator, said voltage discriminator being in a conductive state and presenting a low impedance to said output of said frequency discriminator when a signal present on the communications line has a frequency equal to or exceeding a predetermined frequency and a voltage equal to or exceeding a first predetermined voltage, said voltage discriminator otherwise being in a nonconductive state and presenting a high impedance to said output of said frequency discriminator;
and
a unipolar overvoltage protection device connected to said voltage discriminator and connectable across the communications line, said unipolar overvoltage protection device being in a conductive state and presenting a low impedance to a signal having a positive or negative polarity present on the communications line when said voltage discriminator is in said conductive state, and being in a nonconductive state and presenting a high impedance to the signal present on the communications line when said voltage discriminator is in said nonconductive state.

1 more element

A communications line overvoltage protection circuit connectable to a two-wire communications line upon which a signal having a voltage and a frequency may be present, said circuit comprising:

means for determining a frequency and voltage of a signal on the communications line;
and
overvoltage protection means, connected to and triggerable by said determining means, for providing a low impedance path for the signal in the communications line when the frequency of the signal is within a frequency range and when the voltage of the signal is within a voltage range.

Dependencies are inferred from the claim text.

Frequency selective transient voltage protector

Life of this patent

Frequency selective transient voltage protector

Life of this patent

Abstract

Claims46