Implementing MOSCAP in FPGA (or another digital IC)

Hi,
Can I implement MOSCAP in an FPGA? I mean can I connect drain and source of a transistor to gnd and gate to another node? It can be another device other than FPGA. Thank you.

You should enlighten yourself more about a generic FPGA structure.
Here is some info from Arrow - https://www.arrow.com/en/research-and-events/articles/fpga-basics-architecture-applications-and-uses

Now think how is it possible to "connect drain and source of a transistor to gnd and gate to another node?" in an FPGA structure!

It seems transistor level arrangement is impossible?

What's "possible" depends on how much money
you bring.

An FPGA piece-part sitting on the shelf has all of
its routing done, and a "switch matrix" superimposed
to allow a degree of configurability. But this is at
CLB scale, not loose transistors, and putting a logic
sized series switch in between a decoupling cap
and its current loop will degrade any benefit.

But if you came to (say) Xilinx with 2 wheelbarrows
of large unmarked bills, they'd probably let you touch
Metal1 and contact masks.

As a practical matter I'd play with various external
caps first and only consider deeper digging if that
did not pan out (keeping in mind that the "best"
capacitor might be an effective AC shunt, or
a resonant tank element - critically damped
(ESL+PCB_L)*(C+PCB_C) is the power integrity
ticket; what's the (ESR+PCB_R) that makes it so?