Hi, I am simulating differential cascode OTA with Hspice.  I meet one problem when I do .pz simulation. and
hspice give me following message in the list file:


* project opa_cascode_test_3                                                  
 ******   pole/zero analysis              tnom=  25.000 temp=  25.000        
******  

     input =  0:vin+                 output = v(out+                          


     input =  0:vin+                 output = v(out+                          

**warning** pole analysis stopped - iterno .gt.    100
         xreal=    4.52848E-14 ximag=   -1.11504E-12
***** no poles found *****     coeffd = -3.013e-01    
**warning** zero analysis stopped - iterno .gt.    100
         xreal=    4.12406E-14 ximag=   -1.30545E-12
***** no zeros found *****     coeffn = -8.185e+03    

***** constant factor = -8.185e+03      *****
csdfcntl: error in cio Write funtion
csdfcntl: error in cio Write funtion


Can you help me? thanks a lot!

Best regards!

lianming1