We'd need to know the model number of your Sharp TV to ensure it has the necessary resolution support. Some early HDMI equipped TVs only supported 1080i and 540i via the HDMI input.
I just looked at the specs for the Roku SD, and I see it is a simple standard definition player, with no HDMI output at all. There is no current Roku player that has analog outputs like yours has. Unless your Sharp TV supports 720p and/or 1080p with an HDMI input, there is no Roku (or any other player for that matter) that will work on it.
You are probably aware, but your Roku is so old it is no longer supported, and very few existing channels will work on it. Yeah, it's time to upgrade. Hopefully you don't need a TV update too.
Dan
Roku Stick (3600), Ultra (4640), Ultra (4670), Ultra (4800), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.