Title:
ISDN LINE TERMINATOR
Document Type and Number:
Japanese Patent JP3239936
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To provide a miniaturized low pass filter for improving the S/N of a reception circuit of an ISDN line terminator to an output of a switching DC/DC converter when power is fed from the ISDN line terminator to an ISDN terminator by using a switching DC/DC converter.
SOLUTION: A switching noise is concentrated at the frequency of a zero point of a filter in a reception circuit 14 of the ISDN line terminator 1 and is attenuated by synchronizing a switching clock of a switching DC/DC converter 17 with a clock in synchronism with a line signal extracted by a timing extract circuit 15 of a signal termination circuit 11 of the ISDN line terminator 1. Thus, the S/N is made to be improved, and a transmission range performance not to deteriorate. Furthermore, the size of a low-pass filter provided to the output of the switching DC/DC converter 17 is made small.
Inventors:
Toshihide Hiraoka
Application Number:
JP5974098A
Publication Date:
December 17, 2001
Filing Date:
March 11, 1998
Export Citation:
Assignee:
NEC
International Classes:
H04M19/08; H04L12/02; H04Q3/42; (IPC1-7): H04Q3/42; H04M19/08
Domestic Patent References:
| JP583369A | ||||
| JP58101558A | ||||
| JP10112934A |
Attorney, Agent or Firm:
Yosuke Goto (1 person outside)
Previous Patent: Purified water supply pipeline system
Next Patent: MANUFACTURE OF CONTACT PIN FOR INSPECTING PRINTED WIRING BOARD
Next Patent: MANUFACTURE OF CONTACT PIN FOR INSPECTING PRINTED WIRING BOARD