Triple modular redundancy (TMR) in hardware
ASICs are custom, so you can do what you want. Some FPGAs and CPLDS have built in "rad-hard" (RADiation-HARDened) versions that resist the errors rather than have fault tolerance.

But most FPGAs don't have that feature. On the last space FPGAs I worked on had 3 big FPGAs (Xilinx) for redundancy. A small rad-hard Actel FPGA to perform the  TMR comparison.

Xilinx does have a tool for adding TMR within certain FPGAs.