At UNSW, you'll touch basic circuit design. Albeit, Computer Engineering will go into much more depth of circuit design than Mechatronics.
Mechatronics is pretty much control systems. You can interface control systems with computing, electronics, mechanical systems, chemical reactions, etc.
Electrical is pretty broad in that you can choose multiple different paths. However, it is expected that you learn and become proficient with many aspects of circuit design. You can do control systems as part of Electrical but of course if you take this route then you will learn the Electrical and simple Mechanical aspects behind them (yes you do some mechanics in later years of Electrical).