| 摘要 |
A variable gain amplifier contains first and second amplifying elements for signal amplification, which are differentially connected to a first constant current source. Third and fourth amplifying elements for gain control are differentially connected to a signal input terminal connected to a second constant current source. Fifth and sixth amplifying elements for gain control are differentially connected to a signal input terminal connected to a third constant current source. In addition, an output terminal of the first amplifying element is connected to the second constant current source and an output terminal of the second amplifying element is connected to the third constant current source. The first constant current source is connected to a high potential terminal of a power source and the second and third constant current sources are connected to a low potential terminal of the power source.
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