Environmental Engineering Reference
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of surface mobility due to the high lateral field were also included in
modeling the noise of MOSFET transistors and more complex results
were obtained.
Switches in periodically switched linear circuits are realized using
NMOS transistors operated in the triode region to minimize and
the sub-threshold regions. CMOS pass-transistor gates with comple-
mentary clocks are also used extensively to maximize signal dynamic
range and to minimize the ON-resistance [107, 81], however, at the
expense of complex layout. In the triode region, because is small,
the channel can be approximated by a homogeneous conductor with
conductance given by
The thermal noise generated by the channel is computed in the same
way as that of resistors. When the transistor is in the sub-threshold
region, we follow the same treatment as that in CSIM [105] and BSIM
[108], and set Consequently, the noise is zero. A low-
frequency noise equivalent circuit of MOSFET switches is given in
Fig.11.26. This model has been used widely due to its simplicity
[109,
57,
110, 111].
Noise generated by the extrinsic part of the device includes the ther-
mal noise originating from the source and drain bulk resistances, and
polysilicon gate series resistance. Among them, the thermal noise
of the polysilicon gate series resistance predominates. To analyze
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