A hard 180_x inversion pulse can be replaced by a composite pulse consisting of the 270_x180_-x90_x element. An example is the 1D INADEQUATE experiment using composite pulses (inadcp1d)

Easy implementation on AVANCE spectrometers.

A typical 180 pulse is written as:

...
p1*2 ph1
...
ph1=0

In this case, the composite inversion element would be:

...
p1*3 ph1
p1*2 ph2
p1 ph1
...
ph1=0
ph2=2
where p1 is the 90 pulse.