Amplifiers – With distributed parameter-type coupling means – Distributed amplifier
Patent
1996-08-22
1998-05-12
Mullins, James B.
Amplifiers
With distributed parameter-type coupling means
Distributed amplifier
330254, H03F 360, H03G 330
Patent
active
057511900
ABSTRACT:
A gain-controlled amplifier has a transistor amplifier circuit and a transistor output circuit. The transistor amplifier circuit has an emitter coupled transistor pair for performing signal amplifying and another emitter coupled transistor pair which function as a current sink. The collectors of the transistors of both pairs are coupled to each other. The four transistors of the two pairs have substantially the same collector-emitter voltage vs. collector current characteristic. The output circuit is dc-coupled to the transistor amplifier circuit. An input signal to be amplified is fed to the base of a transistor which is connected to the coupled emitters of the amplifying pair of transistors. A current source is connected to the coupled emitters of the current sink pair transistors. The source current is substantially the same as the current flowing in the coupled emitters of the amplifying pair transistors. During the gain control operation, when current swings from one to the other transistor of the amplifying pair, the respective one of the current sink pair of transistors takes current and thus, the dc level of the collector of the amplifying pair of transistors is stable, with the result that the transistors of the output circuit are not saturated or cut-off. The amplifier gain is controlled by the voltage difference between a reference voltage and a variable gain control voltage which are fed to the bases of the amplifying pair transistors. The gain-controlled amplifier may be utilized in a distributed amplifier with an automatic gain control function.
REFERENCES:
patent: 3891937 (1975-06-01), Bockermann et al.
patent: 5646578 (1997-07-01), Loh et al.
Maulbetsch, "Hi-Fi-Gerat MIT Fernbedienung" Funksham, vol. 49, No. 19, pp. 899,900, Sep. 9, 1977.
Freundorfer Alois Peter
Nguyen The Linh
de Wilton Angela C.
Mullins James B.
Northern Telecom Limited
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