With which supply nwell and pwell (bias) will get connected

If bias analysis is OFF in your UPF.

  pwell of cell will be connected to same supply as primary ground supply.

  nwell of cell will be connected to same supply as primary power supply.

If bias analysis is ON in your UPF.

  pwell of cell will be connected to pwell supply mentioned in the primary supply set of domain.

  nwell of cell will be connected to nwell supply mentioned in the primary supply set of domain.

Example :

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Design :

====

module top(a,b,c,power,ground,nwell,pwell);

MUX  m1 (a,b,c,power,ground,nwell,pwell);

endmodule

UPF:

===

create_power_domain TOP

create_power_domain PD1 -elements {m1 }

create_supply_set SS1 -function {power VDD_1} -function {ground VSS_1}

create_supply_set SS1 -function {pwell VSS_1p} -update

create_supply_set SS1 -function {nwell VDD_1n} -update

create_power_domain PD1 -supply {primary SS1} -update

Result:

===

If bias analysis is OFF in your UPF.

  pwell will be connected to VSS_1

  nwell will be connected to VDD_1

If bias analysis is ON in your UPF.

  pwell will be connected to VSS_1p

  nwell will be connected to VDD_1n