* recursive expansion of parametrized subcircuits

.param w1 1.5 w2 {w1*2}
.param l1 0.15 l2 'l1+0.1'

Xsub1a a b c sub1 w=w1 l=l1
Xsub1b a b c sub1 w=w2 l=l2

.subckt sub1 n1 n2 n3 w l
  * declares w and l parameters instead of nodes:
  w = 1.0
  l = 1.0
  .param w1 = w
  .param l1 = l
  Xsub2a n1 n2 n3 sub2 w=w1 l=l1 m=1
  .param w2 "w+0.0" l2 l*(0.5+0.5)
  Xsub2b n1 n2 n3 sub2 w=w2 l=l2 m=2
.ends 

.subckt sub2 n1 n2 n3 w=0.0 l=0.0 m=0
  Mnmos n1 n2 n3 n1 nmos w=w l=l m=m
.ends