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Battery-feed circuit for exchange
| Details |
Inventors: Kawami, Shigeru; Tabu, Takashi; Sano, Shigeo; Masuda, Nobuyuki;
Assignee: Fujitsu Limited (Kawasaki, JP)
Primary Examiner: Ng; Jin F.
Assistant Examiner: Vaas; Randall S.
Attorney, Agent or Firm: Staas & Halsey
A compact battery-feed circuit for an exchange, including two feedback circuits provided for two wires, one being a dc feedback circuit for the dc voltage on the two wires, and the other being an ac feedback circuit for the ac voltage signal on the two wires. |
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DETAILED DESCRIPTION Accordingly, it is an object of the present invention to provide an improved battery-feed circuit, which can perform the above-described functions, in a circuit of compact construction.
According to a fundamental aspect of the present invention, there is provided a battery-feed circuit for an exchange comprising: a first reference resistance connected to a first wire; a second reference resistance connected to a second wire; a first amplifier with a unity gain and summation function for supplying a speech current and voice signal to the first wire, the input terminal of which is connected to a first direct-current (dc) amplifier, an alternative-current (ac) differential amplifier and a voice signal source, the first direct-current (dc) amplifier having an appropriate dc gain and summation function, the input terminal of which is connected to the first wire and a dc control signal generating circuit, the ac differential amplifier having an appropriate ac gain, the input terminal of which is connected to the first wire and a second line via coupling capacitors; a second amplifier having a unity gain and summation function for supplying a speech current and voice signal to the second wire, the input terminal of which is connected to a second direct-current (dc) amplifier, the alternating current (ac) differential amplifier and the voice signal source, and the second direct-current (dc) amplifier having an appropriate dc gain and summation function, the input terminal of which is connected to the second line.
According to another aspect of the present invention, there is provided a battery-feed circuit for an exchange characterized in that an alternating-current signal appearing between first and second wires is fed back to first and second reference resistances, provided for each of the first and second lines, through an alternating-current feedback path, and in that a direct-current voltage on the first and second wires is fed back independently to the first and second reference resistances by means of a direct-current feedback path, so that a desired alternating-current terminating resistance and a desired direct-current feeding resistance are realized
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Multiplexer-related 
