The Effect Of DC Offsets On A Miller Integrator

* op-amp subcircuits

.subckt ideal_opamp 1 2 3
* connections:      | | |
*              output | |
*             +ve input |
*               -ve input           
Iopen1 2 0 0A
Iopen2 3 0 0A
Eoutput 1 0 2 3 1e6
.ends ideal_opamp

.subckt dc_opamp 1 2 3
* connections:   | | |
*           output | |
*          +ve input |
*            -ve input           
IB1   4 0 DC 200nA
IB2   3 0 DC 200nA
IOS/2 3 4 DC 5nA
VOS    4 2 DC 5mV
Xdc_free_opamp 1 4 3 ideal_opamp
.ends dc_opamp

** Main Circuit **

* inverting amplifier
Vi 3 0 DC 0
Xopamp 1 0 2 dc_opamp
R1 3 2 1k
C2 2 1 10uF
** Analysis Requests **
.TRAN 500ms 10s 0s 500ms UIC
** Output Requests
.PLOT TRAN V(1)
.probe
.end