Title:
HUMIDITY MEASURING DEVICE
Document Type and Number:
WIPO Patent Application WO/2006/057054
Kind Code:
A1
Abstract:
A humidity measuring device comprising an H bridge circuit (10b) for applying an AC voltage to a humidity sensor (10a) by four switches (SW11-14), a resistor drive circuit (11b) for applying a voltage to a reference resistor (11a) by two switches (SW15, SW16), MOS transistors (MN1, MN2) for fixing the operating voltages of these circuits, a current mirror circuit which transmits currents flowing through the H bridge circuit (10b) and the resistor drive circuit (11b) and includes MOS transistors (MP1-4), diode-connected bipolar transistors (QP1, QP2) for converting currents transmitted by the current mirror circuit into voltages and compressing them logarithmically, and a differential amplifier (AMP1) for amplifying the difference of voltages compressed logarithmically.
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Inventors:
MINAMIHATA SHIGEAKI (JP)
Application Number:
PCT/JP2004/017705
Publication Date:
June 01, 2006
Filing Date:
November 29, 2004
Export Citation:
Assignee:
HITACHI ULSI SYS CO LTD (JP)
MINAMIHATA SHIGEAKI (JP)
MINAMIHATA SHIGEAKI (JP)
International Classes:
G01N27/02
Foreign References:
| JPH0712768A | 1995-01-17 | |||
| JP2001281183A | 2001-10-10 | |||
| JPH11108869A | 1999-04-23 | |||
| JP2001244800A | 2001-09-07 | |||
| JPH07311169A | 1995-11-28 | |||
| JP2002034286A | 2002-01-31 | |||
| JPH10239264A | 1998-09-11 |
Attorney, Agent or Firm:
Tsutsui, Yamato (3F Azeria Bldg.,, 1-1, Nishi-shinjuku
8-chome,, Shinjuku-k, Tokyo 23, JP)
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