VARIABLE GAIN TYPE DIFFERENTIAL AMPLIFYING CIRCUIT, AND MULTIPLYING CIRCUIT

Title:

VARIABLE GAIN TYPE DIFFERENTIAL AMPLIFYING CIRCUIT, AND MULTIPLYING CIRCUIT

Document Type and Number:

Japanese Patent JP2003168938

Kind Code:

A

Abstract:

To provide a variable gain type differential amplifier which can materialize high gain and reduced noise at input of a feeble signal even in high frequency regiond, and also can materialize distortion reduction at input of a large signal, and a multiplying circuit using it.

Two FETs 7 and 8 are connected in series between the nodes N1 and N2 connected to the emitters of transistors 1 and 2. An FET 91 is connected between the node between the FETs 7 and 8 and a grounding terminal. The gates of the FETs 7 and 8 are connected to a control terminal NG, which receives control voltage AGC via resistors 11 and 12, respectively. The gate of the FET 9 is connected to a control terminal NG2, which receives control voltage AGC2 via a resistance 13. The control voltages AGC1 and AGC2 change complementarily. The FETs 7, 8, and 9 constitute a variable resistance circuit 20.

Inventors:

BABA SEIICHI

Application Number:

JP2001363754A

Publication Date:

June 13, 2003

Filing Date:

November 29, 2001

Export Citation:

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Assignee:

SANYO ELECTRIC CO

International Classes:

G06G7/16; H03D7/14; H03F1/32; H03F3/45; H03G3/10; (IPC1-7): H03G3/10; G06G7/16; H03D7/14; H03F1/32; H03F3/45

Attorney, Agent or Firm:

Fukushima Shoto

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