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In cmos, both p and n type mosfets have their bulk connected to their source. Then p-types sources are strictly connected to vdd, and n-types sources to gnd.

1: Why not have bulk connected directly to vdd/gnd for p and n respectively?

and

2: Does having bulk connected to source have any effect on mosfets in series, like in a cmos nand gate?

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    \$\begingroup\$ If you want to connect bulk directly to Ground or Vdd, independent of the Source connection, you'd need another pin on the part. \$\endgroup\$ – Peter Bennett Aug 28 '17 at 0:31
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No, in actual CMOS logic — i.e., monolithic ICs — the substrates of both kinds of transistors ARE connected directly to the corresponding supply rails. It is only discrete transistors that normally connect the substrate to the source.

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