Amplifiers – With semiconductor amplifying device – Including differential amplifier
Reexamination Certificate
2005-08-16
2005-08-16
Choe, Henry (Department: 2817)
Amplifiers
With semiconductor amplifying device
Including differential amplifier
C330S133000
Reexamination Certificate
active
06930549
ABSTRACT:
A variable gain amplifier of low amplitude distortion, and low noise, having a large variable range, is provided. A variable gain differential amplifier that controls a gain by use of bias current is used as each of unit amplifiers (VGAs) making up the variable gain amplifier. A large variable gain range is obtained by series-connecting a plurality of the variable gain differential amplifiers. An attenuator is installed on the input side of the unit amplifier (VGA) at least in the initial stage. By doing so, it becomes possible to prevent amplitude distortion from occurring to the respective VGAs. An attenuator utilizing voltage division by capacitors, generating no noise, is used for lowering noise. Further, the variable gain amplifier is provided with a fixed gain amplifier installed in the final stage as necessary in order to obtain a total gain as desired. With the use of the variable gain amplifier as a variable gain amplifier for output power control of a polar loop transmitter, an excellent function for output power control can be achieved without causing significant deterioration in distortion characteristic and noise characteristic thereof.
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Taizo Yamawaki, Masaru Kokubo, Kiyoshi Irie, Hiroaki Matsui, Kazuaki Hori, Takefumi Endou, Hiroshi Hagisawa, Tomio Furuya, Yoshimi Shimizu, Makoto Katagishi and Julian Robert Hildersley, “A 2.7-V GSM RF Tranceiver IC”, IEEE Journal of Solid-State Circuits, vol. 32, No. 12, Dec. 1997, pp. 2089-2096.
Peter B. Kenington, “High Linearity RF Amplifier Design”, Artech House, Inc., 1979, pp. 160-165.
Hikasa Kazuhiko
Kajiwara Hisayoshi
Toyota Kenji
Yamawaki Taizo
A. Marquez, Esq. Juan Carlos
Choe Henry
Fisher Esq. Stanley P.
Reed Smith LLP
Renesas Technology Corporation
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