how to set up in spectre to make crystal oscillator start up

[arsenal]

i have setup a crystal oscillator using inverter
and the netlist is shown as below:

m0 xo xi vdd vdd pch_33 l=0.5u w=2u m=1
m1 xo xi 0 0 nch_33 l=0.5u w=1u m=1
c1 xi 0 16p
c2 xo 0 16p
rf xo xi 1meg
v0 vdd 0 pwl 0 0 100u 3
xi0 xi xi xtal

.subckt xtal n1 n2
rs n1 n5 55k
ls n5 n7 11.233e3 ic=1e-7
cs n2 n7 2.1f
c2 n2 n1 1.1p
.ends xtal

and i have simulated the open loop gain and it's about 16dB, and the
gm at steady state is about 500uS(<gmmax and >gmcrit), however,
after powerup, the oscillator will enter the steady state(xo and xi
remains at about 1.45) and never oscillate.  and i have used
option accurate and method=gear, and transient step is 1ns)
So anyone help me!!Thanks a lot

 

[okguy]

Did you check your phase margin so that it can oscillate?
How long is your simulation? It usually takes ms to start... to speed it
up, you can set an initial current in the crystal inductor.

 

[arsenal]

sure, i have checked the gain which is higher than critical gain and
less than the max gain and is enough for oscilation to startup,
and i have set initial current of the inductor,anyway, the oscillation
will stop after some time.
so what shall i do? how can i setup the hspice options for oscillation
to startup?
thanks