For grins, here is another one to try.? It shows one way to control SPICE's internal timestep while not imposing a harshly small Maximum Timestep across the whole simulation (which would make it crawl):
V1 A 0 PULSE(0 1 4m {Trf} {Trf} 1m 2m)
V2 B 0 SIN (0 1 1000T 4m 0 0 1000)
.step param Trf list 1f 10f 11f 20f 50f 100f 1p
.meas T0 WHEN V(A)=0.01 rise=1
.meas T1 WHEN V(A)=0.99 rise=1
.meas Td param T1-T0
.tran 0 10m
.options plotwinsize=0
Measurement: td
? step t1-t0
? ? ?1 1.01915e-015? <-- 1.02 fs
? ? ?2 9.80032e-015? <-- 9.8 fs
? ? ?3 1.07796e-014? <-- 10.8 fs
? ? ?4 1.95998e-014? <-- 19.6 fs
? ? ?5 4.90007e-014? <-- 49.0 fs
? ? ?6 9.79997e-014? <-- 98.0 fs
? ? ?7 9.8e-013? <-- 0.98 ps
Andy
