FILTER CIRCUIT AND SEMICONDUCTOR INTEGRATED CIRCUIT

Title:

FILTER CIRCUIT AND SEMICONDUCTOR INTEGRATED CIRCUIT

Document Type and Number:

WIPO Patent Application WO/2013/008354

Kind Code:

A1

Abstract:

A filter circuit comprising: a filter main body circuit wherein a first resistance terminal pair having a first variable resistance is connected to a first output terminal pair for a first transconductance amplifier; a replica circuit wherein a second resistance terminal pair having a second variable resistance is connected to a second output terminal pair for a second transconductance amplifier; a first potential imparting unit that applies a first potential to one terminal of the second output terminal pair and outputs a first current; a second potential imparting unit that applies a second potential to the other terminal in the second output terminal pair and outputs a second current; and a control unit that compares the first current and the second current and outputs a control signal. The filter circuit applies the control signal to a second control terminal having the second variable resistance and forms a feedback loop, and also applies the control signal to a first control terminal having the first variable resistance. As a result, the second variable resistance can be accurately controlled such that the composite conductance, formed by the parasitic output conductance of the second transconductance amplifier and the output conductance of the second variable resistance, is 0 or in a positive desired correction state, and good filter characteristics can be achieved.

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Inventors:

WATANABE SEIJI

Application Number:

PCT/JP2012/000200

Publication Date:

January 17, 2013

Filing Date:

January 16, 2012

Export Citation:

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Assignee:

PANASONIC CORP (JP)
WATANABE SEIJI

International Classes:

H03H11/04

Domestic Patent References:

WO2008010331A1

2008-01-24

Foreign References:

JPH10209809A	1998-08-07
JPH06342561A	1994-12-13
JPH07212187A	1995-08-11

Attorney, Agent or Firm:

NAKAJIMA, Shiro et al. (JP)
Shiro Nakajima (JP)

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Claims:

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