common source amplifier

Hi I have a common source amp by active load pmos . I analyse that by hspice. my hand calcoulation for zero and pole is 1=107meg p2=9.44gig and zero= 588gig but .pz analyse give me 5 pole and 4 zero that are not match by my hand calculation? circuit have 2 node then soulde have just 2 pole but.....

common source
.option post accurate

.lib 'E:\mm0355v.l'tt

m1 out g1 0 nmos nch w=60u l=.35u
m2 out g2 vdd pmos pch w=180u l=.35u
m3 g2 g2 vdd pmos pch w=180u l=.35u

Rs in g1 10k

cload out 0 .315p

vdd vdd 0 3.3

i g2 0 1m

.AC lin 700 0.001HZ 20E9HZ

vin in 0 ac=1 dc=.7
.pz v(out) vin
.tf v(out) vin
.Op
.END



***************************************************
****** pole/zero analysis hspice


input = 0:vin output = v(out)

poles (rad/sec) poles ( hertz)
real imag real imag
-55.7539 0. -8.87351 0.
-175.692x 0. -27.9623x 0.
-439.273x 0. -69.9125x 0.
-3.80354g 0. -605.353x 0.
-15.8946g 0. -2.52971g 0.

zeros (rad/sec) zeros ( hertz)
real imag real imag
-56.5843 0. -9.00568 0.
-307.564x 0. -48.9504x 0.
-12.8402g 0. -2.04358g 0.
465.704g 0. 74.1191g 0

Did you check the DC operation (hand vs simulation) ?

Pole/zero hspice analysis results are based on the circuit's DC operating point by the muller method. If something is wrong there, you may get messed up results ...

further check here:

**broken link removed**