DAA hook switch
US7139391B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 12, 2004 |
| Grant date | Nov 21, 2006 |
| Priority date | — |
| Expiry date | Jul 1, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/4902
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A hook switch circuit is shown wherein two high-voltage bipolar transistors, a PNP transistor Q1 and a NPN transistor Q2. that are connected in a regenerative feedback manner to form a bi-stable latch. The regenerative structure permits the use of low beta transistors that may be turned on with a low control current, but still conduct a sufficient off-hook current. Also shown is a polarity steering regenerative switch (MP1, MP2) that provides a power supply voltage from a telephone line pair and may be adapted for a polarity signal and can be combined with a current mirror (MP7) to produce a current signal proportional to the line voltage (LV1).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.