How can I simplify a complex fraction in order to get something of the shape
(a + I b)/(c + I d)?
Note that I would not like Mathematica to further simplify it by multiplying both sides by c - I d.
R1 + 1/(I w C1 + 1/(R2 + 1/(I w C2)))
When I //Simplify it, only the lower fraction gets simplified. I obtain
R1 + 1/(I C1 w + (C2 w)/(-I + C2 R2 w))
R1 - I/((C1 + C2) w) - ( I C2^2 R2)/((C1 + C2) (-I C1 - I C2 + C1 C2 R2 w))
//ComplexExpand separates the whole expression in real and imaginary parts, as expected.