How to check which version of SQLite PDO use?

I used this code before I move to PDO:

    if (class_exists('SQLiteDatabase')) {
        return 'jargon.db';
    } else if (class_exists('SQLite3')) {
        return 'jargon3.db';
    } else {
        throw new Exception('SQLite not installed');
    }

How can I do the same using PDO