Impedance generator for a telephone line interface circuit
US5258713A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 16, 1992 |
| Grant date | Nov 2, 1993 |
| Priority date | — |
| Expiry date | Apr 16, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/738
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An impedance generator, especially suitable for determining a terminating impedance of an active impedance telephone line interface circuit, comprises a subtracting circuit for forming a difference between an input voltage multiplied by a multiplier and a high pass filtered version of the difference multiplied by another multiplier, and a summing circuit for combining the input voltage multiplied by a further multiplier with a low pass filtered version of said difference to produce an output voltage. In one arrangement, the input voltage multiplied by the further multiplier constitutes a third input to the subtracting circuit. The high pass filtered version of the difference is produced by subtracting the output of a low pass filter from the difference. The multipliers are constituted by controllable gain elements, enabling the generated impedance to be easily programmed under digital control.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.