User`s guide

10
-
12 AC Analyses
Anal
y
zin
g
Noise in Probe
Probe supports these output variable formats, which you can use
to view traces for device noise contributions and total input or
output noise at every frequency in the analysis.
*. To find out more about the equations that describe noise behavior, refer to the appropriate device type in the
Analog Devices
chapter in the online
MicroSim PSpice A/D Reference Manual
.
To view this...
Use this output
variable...
Which is represented by this
equation
*
...
F
licker noise for a device NFID(
device_name
)
NFIB(
device_name
)
noise ∝
Shot noise for a device NSID(
device_name
)
NSIB(
device_name
)
NSIC(
device_name
)
For diodes and BJTs:
noise ∝
For GaAsFETs, JFETs, and
MOSFETs:
noise ∝
Thermal noise for the RB, RC, RD, RE,
RG, or RS constituent of a device,
respectively
NRB(
device_name
)
NRC(
device_name
)
NRD(
device_name
)
NRE(
device_name
)
NRG(
device_name
)
NRS(
device_name
)
noise ∝
Thermal noise generated by equivalent
resistances in the output of a digital
device
NRLO(
device_name
)
NRHI(
device_name
)
noise ∝
Total noise for a device NTOT(
device_name
) Sum of all contributors in
device_name
Total output noise for the circuit NTOT(ONOISE)
RMS-summed output noise for the
circuit
V(ONOISE) RMS sum of all contributors
Equivalent input noise for the circuit V(INOISE)
For a break down of noise output
variables by supported device
type, see
Table 17-9 on
page 17-52.
k
f
I
a
f
f
b
-----
⋅
2 qI
4kT
Id
Vd
------
2
3
---
⋅⋅
4kT
R
---------
4 kT
R
---------
NTOT device()
device
∑
NTOT ONOISE()()
VONOISE()
gain
--------------------------------