Title:
【発明の名称】差動オーディオ線受信器
Document Type and Number:
Japanese Patent JPH10511517
Kind Code:
A
Abstract:
A bootstrapped audio line receiver that receives a differential-mode input signal from first and second differential lines and outputs a single-ended signal on an output line. The line receiver includes a differential amplifier and an input amplifier having differential output terminals and differential input terminals. The input amplifier is connected between the differential lines and the differential amplifier. The input amplifier provides a dc current path to a ground terminal while maintaining a high input impedance to ac signals at audio frequencies. The input amplifier also includes an rf filter that removes rf noise without adversely affecting the line receiver's common-mode noise rejection at audio frequencies. In one embodiment, the input amplifier includes two operational amplifiers connected for unity gain and having two bias resistors connected in series between each input terminals of the input amplifier and a ground terminal. A capacitor is connected from the output of each operational amplifier to a node between each set of series connected bias resistors and prevents the low impedance of the bias resistors from significantly degrading the line receiver's common-mode rejection ratio. Thus, the line receiver tolerates a wide range of balanced and unbalanced source impedances with a minimal deterioration of the line receiver's common-mode rejection ratio.
Inventors:
White Rock, William E.
Application Number:
JP52001896A
Publication Date:
November 04, 1998
Filing Date:
December 22, 1995
Export Citation:
Assignee:
White Rock, William E.
International Classes:
H03F3/347; H03F3/45; H04B1/10; (IPC1-7): H03F3/45; H04B1/10
Attorney, Agent or Firm:
Akira Asamura (3 outside)