| 摘要 |
The variable gain amplifier of the invention includes an input node pair, a first output node pair, a voltage-current converter, a plurality of first resistances, a first current source, a second current source, a second output node pair, a third output node pair and a switch circuit. A differential signal supplied to the input node pair is amplified with a predetermined gain (first gain) and output from the second output node pair. The differential signal is also amplified with a gain (second gain) corresponding to the resistance value between one interconnection node and another interconnection node, among the interconnection nodes connecting the plurality of first resistances, connected to the third output node pair via the switch circuit, and output from the third output node pair. The second gain can be changed by changing the two interconnection nodes connected to the third output node pair via the switch circuit.
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