I use one of these _http://store.apple.com/uk/product/MC748ZM/A/apple-composite-av-cable with a 3GS.
Dont know if it would do with a 3S but sure there must be a similar version out there.

There is also used to be a component version available which apple no longer seem to sell but can be sourced through google.
The choice would depend on how you want to connect up to your Bravia and the inputs it has available.


There are also problems with iPhone to TV so I have jailbroken mine and installed an app called 'DisplayOut' to help.

Hope this helps you out.