jawlin2
Newbie level 4
how to simulate op amp noise
Hi All,
When I used .noise to simulate the output noise of a op amp (DC gain=80dB, GBW=50MHz) using HSPICE, I had a unreasonably high noise, about 521mV at 100MHz. My partial code and result are as below. Is the code or result correct? If not, please help to fix the code. Thank you.
Partial code:
***input
E1 vp vicm vid avss 0.5
E2 vn vicm vid avss -0.5
vicm vicm avss dc 0.9v
vid vid avss ac 1v
***stimulus
.ac dec 10 1 100meg
.noise v(vout) vid 10
Partial result:
frequency = 100.0000x hz
**** total output noise voltage = 273.3595a sq v/hz
= 16.5336n v/rt hz
transfer function value:
v(vout)/vid = 422.0727m
equivalent input noise at vid = 39.1724n /rt hz
**** the results of the sqrt of integral (v**2 / freq)
from fstart upto 100.0000x hz. using more freq points
results in more accurate total noise values.
**** total output noise voltage = 521.6792m volts
**** total equivalent input noise = 363.4873u
Hi All,
When I used .noise to simulate the output noise of a op amp (DC gain=80dB, GBW=50MHz) using HSPICE, I had a unreasonably high noise, about 521mV at 100MHz. My partial code and result are as below. Is the code or result correct? If not, please help to fix the code. Thank you.
Partial code:
***input
E1 vp vicm vid avss 0.5
E2 vn vicm vid avss -0.5
vicm vicm avss dc 0.9v
vid vid avss ac 1v
***stimulus
.ac dec 10 1 100meg
.noise v(vout) vid 10
Partial result:
frequency = 100.0000x hz
**** total output noise voltage = 273.3595a sq v/hz
= 16.5336n v/rt hz
transfer function value:
v(vout)/vid = 422.0727m
equivalent input noise at vid = 39.1724n /rt hz
**** the results of the sqrt of integral (v**2 / freq)
from fstart upto 100.0000x hz. using more freq points
results in more accurate total noise values.
**** total output noise voltage = 521.6792m volts
**** total equivalent input noise = 363.4873u
