發本書Parasitic-Aware Optimization of CMOS RF Circuits

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1.
In the near future, people’s daily activities will be dominated with
portable wireless devices. To make compact and energy efficient mobile
communicating equipment such as mobile phones, wireless modems, twoway
radios, etc., integrated circuit technology (IC) is necessary because it
not only reduces the size, weight, and power consumption of such devices, it
enables manufacturers to include greater functionality at lower costs. Figure
1-1 shows a general system-on-chip (SOC) solution that comprises digital,
analog, micro-electro-mechanical systems (MEMS), and radio frequency
(RF) circuit blocks. By implementing a sensor in conjunction with an RF
front end, the SOC can receive or transmit data from external sources. The
digital circuitry on the chip consists of CPU, DSP, and memory blocks, and
is used for data processing. Analog-to-digital converters (ADC) and digitalto-
analog converters (DAC) enable the communication of information
between the digital and analog circuits.
It was not long ago that all RF circuits were implemented using gallium
arsenide (GaAs) or bipolar junction transistor (BJT) technologies. CMOS
technology was not viable due to its low values of breakdown voltage,
small-signal transconductance, and unity current gain frequency
Moreover, the lossy silicon substrates contributed a plethora of parasitic
elements to the monolithic passive components that made CMOS inferior to
its bipolar and GaAs counterparts.
However, because CMOS has dominated the world of digital ICs for
more than a quarter century and has achieved a very high level of integration,

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Chapter 4
OPTIMIZATION OF CMOS LOW NOISE
AMPLIFIERS
1. LOW NOISE AMPLIFIER
The low noise amplifier is the first block in the receiver chain and is used
to amplify the weak RF signal arriving from the external antenna, duplexer
switch, and band select filter. Since the signal from the antenna is very weak,
the amplifier is required to add small noise yet provide high gain; hence, the
name low noise amplifier. To minimize the various noise contributions of
the amplifier circuits, the noise source needs to be carefully analyzed and
subsequently optimized.
1.1 Noise
Two different types of noise sources exist in low noise amplifiers:
thermal noise generated by resistors, including parasitic resistances, and
noise generated by the active devices.
1.1.1 Thermal noise
The basic thermal noise equations are (Fig. 4-1) [1]

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Chapter 7
OPTIMIZATION OF CMOS RF POWER
AMPLIFIERS
1. RF POWER AMPLIFIERS
The main purpose of the PA is to amplify the transmit signal so that it
can reach the receiver at a specified distance. Depending on the distance
between transmitter and receiver, the output power of PA is determined, and
depending on the method of modulation, the type of power amplifier is
decided. If the modulation scheme used is highly linear such as Binary Phase
Shift Keying (BPSK), a linear PA is required. Since the PA dissipates a lot
of the power, high efficiency is necessary to improve the battery life for
mobile wireless systems. Also if the power efficiency is low, the temperature
of the chip will be increased which degrades the performance and an
expensive and bulky cooling system may be required. So, the power
efficiency and linearity of the PA are very important. Usually, a linear PA
has lower power efficiency than a nonlinear PA. There are several types of
PAs, class-A, B, AB, C, D, E, and F. Class-A, B, AB are highly linear PAs,
while class-C is somewhat nonlinear PA. Class-D, and Class-E are highefficiency
nonlinear switching PAs. Class-F is a high efficiency nonlinear
PA obtained by creating a square-wave overdrive voltage using harmonic
shaping. First, Class-A, B, AB, C amplifiers are discu