Speech network for a telephone set employing an electromagnetic transducer

Claim 2

A transmitter branch for a telephone speech network compRising, in combination, an electromagnetic transmitter, means for amplifying the output of said transmitter, means for splitting the output current from said amplifying means into first and second nonreactive portions having a fixed ratio, means for utilizing one of said current portions as feedback to stabilize said amplifying means, and means for utilizing the other of said current portions to compensate for nonlinearity of said amplifying means, wherein said amplifying means comprises a two stage, direct coupled transistor amplifier, said utilizing means including means for applying feedback from the collector electrode of the second stage of said amplifier to the emitter electrode of the first stage of said amplifier, and means for applying the output of said transmitter to the base electrode of the first stage transistor of said amplifier.

Claim 3

Apparatus in accordance with claim 1 wherein said splitting means comprises first and second parallel circuit paths, said first circuit path including a diode and a resistive circuit device connected between the output of said amplifier and a power supply path, said second circuit path including a resistive circuit device and a diode connected between the output of said amplifier and a power supply path, said diodes and said resistive circuit devices being connected in opposite order in said first and second circuit paths.

Claim 4

Apparatus in accordance with claim 2 including means for biasing said amplifier, said biasing means comprising first and second resistors in series relation, said transmitter being bridged between the junction point of said first and second resistors and the input point of said amplifier, means connecting the junction point between said resistive circuit device and said diode in said second circuit path to the unconnected terminal of said second resistor, means connecting the unconnected terminal of said first resistor to the emitter electrode of the output transistor of said amplifier, and said applying means comprising means connecting the junction point between said diode and said resistive circuit device in said first circuit path to the emitter electrode of the input transistor of said amplifier.

Claim 5

Apparatus in accordance with claim 3 including a third resistive device connecting the junction between said first and second resistors to said supply path.

Claim 6

A transmitter branch for a telephone speech network comprising, in combination, first and second supply leads, an electromagnetic transmitter, a two stage, direct coupled transistor amplifier, means for furnishing stabilizing feedback for said amplifier comprising a first diode and a first resistive element connected in series between the collector electrode of the output transistor of said amplifier and said first supply lead, means for compensating for the nonlinearity of the transistors of said amplifier comprising a second resistive element and a second diode connected in series between said collector electrode and said first supply lead, biasing means comprising third and fourth resistors in series relation connected between said second supply lead and the junction between said second resistor and said second diode, an electromagnetic transmitter connected between the junction point of said third and fourth resistors and the base electrode of the input transistor of said amplifier, means connecting the emitter electrode of said output transistor to said second supply lead, and means connecting the emitter electrode of said input transistor to the junction point between said first resistor and said first diode.

Claim 7

A transmitter branch for a telephone speech network comprising, in combination, first and second supply leads, an electromagnetic transmitter, a two stage, direct coupled transistor amplifier, means for furnishing stabilizing feedback for said amplifier comprising a first diode and a first resistive element connected in series between the collector electrode of the output transistor of said amplifier and said first supply lead, means for compensating for the nonlinearity of the transistors of said amplifier comprising a second resistive element and a second diode connected in series between said collector electrode and said first supply lead, biasing means comprising third and fourth resistors in series relation connected between said second supply lead and the junction between said second resistor and said second diode, an electromagnetic transmitter connected between the junction point of said third and fourth resistors and the base electrode of the input transistor of said amplifier, means connecting the emitter electrode of said output transistor to said second supply lead, and means connecting the emitter electrode of said input transistor to the junction point between said first resistor and said first diode.

Claim 8

Apparatus in accordance with claim 5 including a fifth resistor bridging the junction point between said third and fourth resistors and said first supply lead.

Claim 9

Apparatus in accordance with claim 6 including a sixth resistor shunting said transmitter.