I came across the following statement
"The output impedance and the minimum required |Vds| of M2 is less strongly coupled than the value and voltage drop of a resistor. The voltage |Vds2,min| = |Vgs2-Vth2| can be reduced to even a few hundred milivolts by simply increasing the width of M2."
The circuit is M1(nmos) and M2(pmos) connected thru their drain where Vout is measured. M2 is connected to Vdd at source where M1 is connected to GND at source. Vb is applied at M2's gate while Vin is apply at M1's gate.
May I know what is the meaning of coupling here means? I often bump into the term 'coupling' but I do not know what does it mean.
Thank you all