How are the electrical pulses that are bits put onto the wire? What physical component on the NIC is actually sending these at seemingly impossible speeds?

I was thinking of how insane gigabit internet is when you think of the millions of bits that are sent in such a brief amount of time.

What physical component of the NIC / computer is actually “writing”/sending these onto the wire?

I compare it to Morse code via Telegraph. There must be some physical gate that sends the bit.

Thanks.