Title:
BIAS CIRCUIT FOR AMPLIFIER
Document Type and Number:
Japanese Patent JPH05299958
Kind Code:
A
Abstract:
PURPOSE: To obtain a bias circuit which changes in accordance with the presence/absence of a calling signal in an amplifier used for a ring trip circuit, does not change abruptly, and does not consume much energy. CONSTITUTION: A bias circuit which can connect a bias impedance to the input of an amplifier SA to which input signals are supplied has such a feature that the circuit detects the magnitude of the input signals and decides the value of a bias impedance based on the detected magnitude. The circuit is composed of the terminal I1 of the amplifier SA and a negative feedback loop connected between the terminals I1 and 12 of the amplifier SA and, when the input voltage at the terminal I1 exceeds a reference value, the circuit adjusts the terminal voltage of the amplifier to the reference value by connecting variable bias impedances R6, PNP1, R7, and PNP2 between the input terminal and the terminal VBAT of the amplifier SA.
Inventors:
EDEI RUI MARII UIROTSUKUSU
YOHAN GABURIERU AUGUSUTO FUERU
YOHAN GABURIERU AUGUSUTO FUERU
Application Number:
JP33639992A
Publication Date:
November 12, 1993
Filing Date:
December 16, 1992
Export Citation:
Assignee:
ALCATEL NV
International Classes:
H03G5/16; H03F3/45; H04M3/22; H04M19/02; (IPC1-7): H03G5/16
Attorney, Agent or Firm:
Takehiko Suzue