Radio Frequency Integrated Circuit Design - Webs

A Brief Review of Technology
The transconductance is given by the derivative of the current with respect
to the input voltage. For the simple square law equation, this becomes
g m = di DS
= �C
dv ox�
GS
W
L � (v GS − VT )(1 + �v DS ) (3.32)
This can also be shown to be equal to (note the � term has been left out)
W
g m = 2�Cox √ L IDS
In the triode region of operation, current is given by
61
(3.33)
i DS = �Cox�W L ��vGS − VT − v DS
2 �v DS (1 + �v DS ) (3.34)
In practice, for RF design, short-channel devices are used. The equations
for these devices are poor; thus, it is necessary to use simulators to find the
curves. However, even the more complex models used in the simulators are
also typically poor, especially in modeling output conductance and phase shift
at high frequency. Thus, measurements are needed to verify any designs or to
refine the models.
References
[1] Taur, Y., and T. H. Ning, Fundamentals of Modern VLSI Devices, Cambridge, England:
Cambridge University Press, 1998.
[2] Plummer, J. D., P. B. Griffin, and M. D. Deal, Silicon VLSI Technology: Fundamentals,
Practice, and Modeling, Upper Saddle River, NJ: Prentice Hall, 2000.
[3] Sedra, A. S., and K. C. Smith, Microelectronic Circuits, 4th ed., New York: Oxford
University Press, 1998.
[4] Terrovitis, M. T., and R. G. Meyer, ‘‘Intermodulation Distortion in Current-Commutating
CMOS Mixers,’’ IEEE J. of Solid-State Circuits, Vol. 35, No. 10, Oct. 2000,
pp. 1461–1473.
[5] Roulston, D. J., Bipolar Semiconductor Devices, New York: McGraw-Hill, 1990.
[6] Streetman, B. G., Solid-State Electronic Devices, 3rd ed., Englewood Cliffs, NJ: Prentice
Hall, 1990.
[7] Muller, R. S., and T. I. Kamins, Device Electronics for Integrated Circuits, New York: John
Wiley & Sons, 1986.