Integrated ringer relay circuit and method
AssigneeHarris Corporation
InventorGerald M. Cotreau
Life of this patent
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Abstract
A circuit and method for isolating a subscriber line interface circuit ("SLIC") from the ringer generator in a telephone system. The circuit uses a gain blocking device to provide a signal gain when the ringer generator is not being utilized and to provide a high impedance when a ringer signal is present. The high impedance may be provided through an amplifier circuit which is tri-stated when the amplifier is not energized.
Claims31
A circuit for a telephone system comprising:
- a subscriber line interface circuit ("SLIC") having tip and ring paths electrically interconnecting the SLIC and a telephone instrument;
- a ringer generator for generating a ringer signal;
- relay means for selectively applying said ringer signal to said tip and ring paths;
- and
- a selectively operable gain-setting blocking device having an amplifier capable of going into a tri-state mode isolating the SLIC from said ringer signal.
A circuit for isolating ringer signals from a SLIC in a telephone system comprising:
- tip and ring paths electrically interconnecting a SLIC and a telephone instrument;
- a ringer generator for generating a ringer signal;
- selectively operable relay means for applying said ringer signal to said tip and ring paths;
- a selectively operable gain-setting blocking device isolating the SLIC from said ringer signal, said blocking device comprising an amplifier and means for driving said amplifier, wherein said means for driving comprises,
- a first current source,
- a first bipolar transistor;
- and,
- a first blocking diode;
- said first current source, said first transistor and said first diode being electrically connected in series to said amplifier.
A telephone line circuit for isolating ringer signals from a subscriber line interface circuit (SLIC) comprising:
- tip and ring paths electrically interconnecting a SLIC and a telephone instrument;
- a ringer signal;
- selectively operable relay means for selectively applying said ringer signal to said tip and ring paths;
- and
- a selectively operable gain-setting blocking device having an amplifier capable of going into a tri-state mode isolating the SLIC from said ringer signal.
In a telephone line circuit having a subscriber line interface circuit (SLIC) electrically interconnected with a tip path and a ring path, means for selectively applying a ringer signal to the telephone line and means for isolating said SLIC from said ringer signal, the improvement wherein a selectively operable gain-setting blocking device having a current gain blocking device isolates portions of the SLIC from said ringer signal.
In a telephone line circuit having a subscriber line interface circuit (SLIC) electrically interconnected with a tip path and a ring path, a ringer signal which is selectively applied to the telephone line and means for isolating said SLIC from said ringer signal, the improvement comprising a selectively operable gain-setting amplifier for isolating portions of the SLIC from said ringer signal, and means for driving said amplifier, wherein said means for driving comprises,
- a first current source,
- a first bipolar transistor;
- and,
- a first blocking diode;
- said first current source, said first transistor and said first diode being electrically connected in series to said amplifier.
Dependencies are inferred from the claim text.