Echoing An '&' Character?

I'm trying to figure out how to include an '&' character in a php echo. I'm not looking for the html & a m p ; special character, but the actual character, since i'm trying to do this: Code:

echo "<A HREF"/download.php?type=wallpaper&file=$filename">Download</A>";

instead it returns a link such as this: Code:

/download.php?type=wallpaperfile=wallpaper.zip