Arrangement in a subscriber line interface circuit

US6195429A · kind A · utility

Assignee

• Telefonaktiebolaget LM Ericsson (Publ) · SE

Inventors

• Anders Emericks · Sundbyberg, SE
• Henrik Hellberg · Solna, SE
• Mattias Israelsson · Stockholm, SE
• Carl-Henrik Malmgren · Stockholm, SE

Key dates

• Filing date: Apr 2, 1998
• Grant date: Feb 27, 2001
• Expiry date: Apr 2, 2018

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04B3/48
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

In a subscriber line interface circuit connected to a telephone line having a high potential wire and a low potential wire, an arrangement for generating a signal for determining the line voltage comprises means (7, 10, 11) for alternately charging a capacitor (6), by means of a first DC current, to a first voltage, and discharging the capacitor (6), by means of a second DC current, to a second voltage. Hereby, a sawtooth wave having an amplitude corresponding to the difference between the first and second voltages is produced. This sawtooth wave is converted to a pulse train related to the line voltage, from which the line voltage can be determined.