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Machine translation
1. (WO1981002232) ELECTRICAL AMPLIFIER
Latest bibliographic data on file with the International Bureau   

Pub. No.:    WO/1981/002232    International Application No.:    PCT/SE1980/000025
Publication Date: 06.08.1981 International Filing Date: 28.01.1980
IPC:
H03F 3/08 (2006.01), H03F 3/45 (2006.01), H03F 3/68 (2006.01)
Applicants:
Inventors:
Priority Data:
SE80/00025 28.01.1980 WO
Title (EN) ELECTRICAL AMPLIFIER
(FR) AMPLIFICATEUR ELECTRIQUE
Abstract: front page image
(EN)Outer offset voltages for electrical amplifiers with high input impedance are difficult to obtain with preservation of the high impedance both for the resistive and capacitive part. One solution of the problem is to connect photo diodes (1) in series to the input of the amplifier (5) and illuminate these with the light from a lamp (9), which intensity varies with the voltage (10) of the lamp. A resistor (11) is connected in parallel with the photo diodes. From the connector (15) for the input voltage, AC voltages are fed directly to the input of the amplifier (5) by a bypassing capacitor (19). Due to the small dimensions of the diodes (1), capacitor (19) and resistor (11) the leakage capacitance will be very small. Further amplifiers (6, 7 and 8) can be given outer offset voltages by means of the light from the same lamp. By means of small shields (23, 24) photo diodes in different amplifiers can be shaded making the outer offset voltages individually adjustable.
(FR)Il est difficile d"obtenir des tensions decalees exterieures pour des amplificateurs electriques a haute impedance d"entree en preservant une haute impedance tant pour la partie resistive que pour la partie capacitive. Une solution du probleme consiste a connecter des photodiodes (1) en serie a l"entree de l"amplificateur (5) et a illuminer ces photodiodes avec la lumiere provenant d"une lampe (9), dont l"intensite varie avec la tension (10) de la lampe. Une resistance (11) est connectee en parallele aux photodiodes. A partir du connecteur (15) pour la tension d"entree, des tensions de courant alternatif sont envoyees directement a l"entree de l"amplificateur (5) au moyen d"un condensateur de deviation (19). Etant donnees les faibles dimensions des diodes (1), du condensateur (19) et de la resistance (11) la capacite de fuite est tres faible. On peut envoyer a d"autres amplificateurs (6, 7 et 8) des tensions externes de compensation au moyen de la lumiere emise par la meme lampe. Au moyen de petits ecrans (23, 24) les photodiodes des differents amplificateurs peuvent etre couverts, ce qui permet de regler individuellement les tensions de compensation.
Designated States:
Publication Language: English (EN)
Filing Language: English (EN)