CMOS Technology
Characterization
for Analog and RF Design
Author : Behzad Razavi
Presenter : Kyungjin Yoo
Index
I.
II.
III.
IV.
Introduction
Motivation and Issues
Characterization for analog design
Characterization for RF design
I.

Introduction
CMOS: inadequate for analog and RF design?




Sophisticated set of characteristics


Limited active, passive devices
Optimized technology for digital design
Poor characterization and modeling
speed, noise, linearity, loss, matching, and dc
characteristics
Technology characterization methods
II.

Motivation and Issues
Tradeoff difference

digital CMOS technology vs. analog circuits
speed  power dissipation
II.

Need for analog characterization



Motivation and Issues
Inaccurate modeling, lack of modeling
Rapid migration of digital circuits
Difficulties





Various systems
Difficult to measure
Difficult to incorporate in simulations
Time and effort
Modification for next generation
III. Characterization
for analog design
A.
B.
C.
D.
E.
F.
DC Behavior
AC Behavior
Linearity
Matching
Temperature Dependent
Noise
A. DC Behavior



Have measured I-V
data points
Subthreshold characteristics of MOSFET
Output resistance of short-channel MOS
transistors
B. AC Behavior

device level




and
must be measured under bias conditions
Nonlinearity of MOS gate-channel capacitance
Capacitance of the n-well to the substrate
circuit level


Frequently used building blocks as test vehicles (e.g.
ring oscillators)
Voltage comparator for intrinsic speed of the technology
C. Linearity

Passive devices



.
Coefficients
be measured
must
Active devices


Minimize the nonlinearity
by adequate open-loop
gain
Quantify the overall
nonlinearity using Fig.10
D. Matching
E. Temperature Dependence

Basic device parameters


Other quantities


Output resistance, subthreshold conduction,
capacitance
Transconductance, on-resistance, threshold
voltage, ac properties
DC and AC temperature dependencies of
devices must be measured and
incorporated in simulations
IV.
A.
B.
C.
Characterization for RF design
Device Properties
Noise
Circuit Properties
A. Device Properties




Limit active devices, More passive monolithic
devices
Inductors - measured data for parameters
Varactors
Transformers
B. Noise

Thermal noise of submicrometer
MOS transistor
long-channel
approximation




Capacitive coupling of the drain
noise current to the gate
Modulation of the threshold voltage
by the body thermal noise
1/f noise of MOSFET’s
Values to be measured
are too small to be sensed
C. Circuit Properties

Dependent on



Overall transceiver architecture
Intended wireless standard
Issues in today’s RF CMOS design




Variability of device and circuit parameters with
process and temperature
Matching properties
Frequency divider
Power Amplifiers
Thank you !
Q&A