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1. WO1994029951 - METHODS AND APPARATUS FOR MICROPHONE PREAMPLIFICATION

Publication Number WO/1994/029951
Publication Date 22.12.1994
International Application No. PCT/US1994/006257
International Filing Date 02.06.1994
IPC
H03F 3/183 2006.01
HELECTRICITY
03BASIC ELECTRONIC CIRCUITRY
FAMPLIFIERS
3Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
181Low-frequency amplifiers, e.g. audio preamplifiers
183with semiconductor devices only
H03F 3/187 2006.01
HELECTRICITY
03BASIC ELECTRONIC CIRCUITRY
FAMPLIFIERS
3Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
181Low-frequency amplifiers, e.g. audio preamplifiers
183with semiconductor devices only
187in integrated circuits
CPC
H03F 3/183
HELECTRICITY
03BASIC ELECTRONIC CIRCUITRY
FAMPLIFIERS
3Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
181Low frequency amplifiers, e.g. audio preamplifiers
183with semiconductor devices only
H03F 3/187
HELECTRICITY
03BASIC ELECTRONIC CIRCUITRY
FAMPLIFIERS
3Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
181Low frequency amplifiers, e.g. audio preamplifiers
183with semiconductor devices only
187in integrated circuits
Applicants
  • APPLE COMPUTER, INC. [US]/[US]
Inventors
  • HEYL, Lawrence, Frederick
  • FARRAR, Douglas, Mann
Agents
  • FERNANDEZ, Dennis, S.
Priority Data
08/071,51303.06.1993US
Publication Language English (EN)
Filing Language English (EN)
Designated States
Title
(EN) METHODS AND APPARATUS FOR MICROPHONE PREAMPLIFICATION
(FR) PROCEDE ET DISPOSITIF DE PREAMPLIFICATION DES MICROPHONES
Abstract
(EN)
Preamplifying circuitry amplifies sound signals for input into a computer system. A first stage common-emitter amplifier (16) provides high-gain amplification of the input signal, while a second stage amplifier (18) comprising an operational amplifier is suitable for driving a cable with the amplified sound signal. A low-cost constant voltage source (14) comprising a diode (26) and an operational amplifier (21a) supplies a voltage reference to both amplifier stages (16, 18) with a very high rejection of system noise. The circuitry and methods provide a low-cost, easily manufactured preamplifier suitable for sound input in desktop computing devices.
(FR)
Les circuits du préamplificateur amplifient les signaux son en entrée du système informatique. Un premier étage constitué d'un amplificateur (16) à émetteur commun, procure au signal d'entrée un fort gain. Un second étage d'amplification (18) comportant un amplificateur opérationnel permet le passage du signal son amplifié par un câble. Une source de tension (14) peu coûteuse constituée d'une diode (26) et d'un amplificateur opérationnel (21a) délivre une tension de référence aux deux étages d'amplification (16, 18) avec une importante réjection des bruits système. Ces circuits et ces procédés permettent de réaliser à bon compte et facilement des préamplificateurs des sons en entrée pour les systèmes informatiques de bureau.
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