provide link to rss per category

Hi.
I’m using the following php to provide an rss feed:

<a href="<?php bloginfo('rss2_url'); ?>" target="_new">rss feed</a>

What I’d like to do is have this link reflect the current category – so if we are on the blog index – provide rss from all categories (default setting) and if a user clicks into a category then this link would provide rss for only that category.

Is this possible with a bit of get_the_category_by_ID($cat) and all that?

Thanks.