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PZ analysis in spectre and hspice

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alvays

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spectre pz analysis

INDEX: pz analysis; hspice; spectre; pole and zero

I just do the pz analysis with spectre(analog simulation environment) and hspice on the same circuit: a two stage op amp with differential input and single output
Their bode plot same as each other, but the report are different:
Hspice's report is correspondance with the bode
But spectre's report is wrong, also I can only get 2 poles and 2 zeros( How can I set the options?).

Anybody comes to this before? Or I have set the options of pz in spectre wrong?

HSPICE:
poles (rad/sec) poles ( hertz)
**********************************************************************
real imag real imag
0. 0. 0. 0.
-5.0734k 0. -807.4560 0.
-23.2417x 0. -3.6990x 0.
-139.6991x 0. -22.2338x 0.
-533.9424x 0. -84.9796x 0.
-935.9903x 0. -148.9675x 0.
-1.4271g 0. -227.1237x 0.
zeros (rad/sec) zeros ( hertz)
**********************************************************************
real imag real imag
0. 0. 0. 0.
-137.5430x 0. -21.8906x 0.
-762.5724x 0. -121.3672x 0.
-1.2621g 0. -200.8615x 0.
-1.4666g 0. -233.4214x 0.
2.0379g 0. 324.3371x 0.
2.8481g 0. 453.2941x 0.

SPECTRE
freq=100
Poles(Hz)
Real Imaginary Qfactor
Pole_1 -1.01495e-05 0.00000e+00 5.00000e-01
Pole_2 -1.57046e+03 0.00000e+00 5.00000e-01
Zeros(Hz)
Real Imaginary Qfactor
Zero_1 3.26548e-10 0.00000e+00 -5.00000e-01
Zero_2 -4.82145e+07 0.00000e+00 5.00000e-01
Network function gain(magnitude)= 5.06194e-01
 

pz spectre

it seems that the spectre has delete the pole and zero whose value is nearly the same.
 

pz analysis

hihi,

how do you run the poles and zero analysis in spectre? please advise

thanks
 

I have the problem, too.
My Spectre pz analysis results doesn't match Bode's plot.
My simulation is for LDO circuits.
Poles (Hz)

Real Imaginary Qfactor

Pole1 -3.18776e-02 0.00000e+00 5.00000e-01

Zeros (Hz) at V(Vout1V2,REGVSS)/V0

Real Imaginary Qfactor

Zero1 -3.15705e-01 0.00000e+00 5.00000e-01

Constant factor = 2.02118e-01

DC gain = 2.00170e+00
 

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