Install SQLite extension in Yii2

Good day I am trying to connect my application in Yii2 with a database in SQLite but I present this error: The configuration for the "db" component must contain a "class" element.

This is my configuration file

return ['components' => [      
    'db' => [
        'class' => 'yii\db\Connection',
        'dsn' => 'sqlite:/softwareoperacional.db',
    ],
  ], 
];