| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable gain differential amplification circuit exhibiting good linearity to a differential input voltage. SOLUTION: The differential amplification circuit comprises a first differential MOS transistor M1 and a second differential MOS transistor M2, a first constant current source 11 connected with the source of the first differential MOS transistor M1 and a second constant current source 12 connected with the source of the second differential MOS transistor M2, and a variable resistor element 20 connected between the sources of the first differential MOS transistor M1 and the second differential MOS transistor M2. The variable resistor element 20 comprises twelve P channel type MOS transistors M3-M14 connected in series and having gates being applied with a DC control voltage VCNT commonly through an operational amplifier 16. COPYRIGHT: (C)2006,JPO&NCIPI
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