Sine wave to square wave
The simplest way to meet your design criteria is with a high-speed mid-reference comparator... like so:







simulate this circuit &ndash; Schematic created using CircuitLab

The precise value of the resistors is not important so long as they are matched. Lower values will be more stable vs. temperature and manufacturing variation, while higher values will be more energy efficient.

I've made a number of assumptions here that you will need to ensure are valid in your application:


You have sufficient gain-bandwidth-product (GBP) in the Op-amp you select. If you don't need any gain (x1) then you need at least 30MHz GBP.
The voltage of your sine-wave signal is also mid-reference (it's "zero" is halfway between your V+ and V- used with the Op-Amp.
Your input signal's dynamic range fits within the input range of the Op-Amp.