Can anyone tell me if there is any special software used to produce such block-diagrams? I have used Visio and Simulink but none was satisfying like this one.
You can make it with MS Visio. A sample:
But do not expect it's easy. You cannot draw it by dragging symbols from preset stencils + typing texts + inserting connection lines. You must do it by using Visio like a normal vector drawing program.
That's not Visio's strong area. Visio is a tool for structured multilevel documentation. The drawing tools in Visio support it, but they are not good for arty visual designs with complex curves and rich colorings. Multilevel means that in Visio one can for ex. make clicking a block to open the internals of that block.
As well you can take Inkscape, which has better drawing tools. Visio soon runs out of steam if you need finer forms than your current diagram has.
Of course, in vector drawing programs you can build a template which contains a good collection of needed shapes and text symbols. They can be placed into a custom symbol palette (=a custom stencil in Visio). After creating it drawing is much faster.