Title:
【発明の名称】インピーダンス回路網を用いる可変利得増幅器
Document Type and Number:
Japanese Patent JP2002519920
Kind Code:
A
Abstract:
A circuit includes a transconductance device which converts an input signal voltage to a signal current. An output terminal is coupled to receive signal current from the transconductance device. A gain-control circuit has an impedance network coupled to the output terminal to maintain a constant impedance at the output terminal and selectively steers current from the transconductance device through at least first and second different nodes of the impedance network to vary the current supplied to the output terminal. The circuit has reduced noise figure degradation as compared to known current steering circuits by controlling gain without dumping signal current directly to the supply and without changing the impedance at the output terminal. The circuit is particularly useful in the RF section of radio receivers and transmitters, such as in cellular phones.
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Inventors:
Keng, El Fong
Application Number:
JP2000557541A
Publication Date:
July 02, 2002
Filing Date:
June 10, 1999
Export Citation:
Assignee:
Konin Krekka Philips Electronics NV
International Classes:
H03G1/00; H03G1/04; H03G3/10; H03F1/08; (IPC1-7): H03G3/10; H03F1/08; H03G1/04
Attorney, Agent or Firm:
Kazuo Sato (3 others)