How is this directly coupled- output of stage 1 directly connected to input of stage 2. Explain with diagrams?

A buck-boost converter operates with an input battery. It converts +12 V to –12 V at apower level of about 75 W. the switching frequency is 120 kHz. The switches have200 ns switching time. The battery has an internal series resistance of 0.2  and seriesinductance of 200 nH. (a) What is the operating value of the duty ratio? What power is lost in the battery resistance? (b) Propose an interface structure to improve operation and decrease losses. What are the duty ratio and battery         resistance loss with your interface in place?

I need a diagram of a circuit by the transform and rectification block, using the bridge rectifier circuit (2W10). It can be a source of any value. You don't need to do any calculations, just a drawing of how this circuit will look, please.