EECS 142/242A

Course Overview
Spring 2025
Prof. Ali M. Niknejad
University of California, Berkeley
 Course Logistics
• Instructor: Ali Niknejad
(niknejad@berkeley.edu)
• Graduate Student Instructors:
• Hesham Beshary (discussion)
• Kunmo Kim (lab)
• Yahia Ibrahim (lab)
• Course websites:
• bCourses – HW posting and submission, video links
• Ed– for students to learn from each other, monitored by instructors
on a daily (not hourly) basis

• No office hours in the first week

Ali M. Niknejad University of California, Berkeley EE142/242A 2

 Textbook
• There is no required textbook for the course. Course
notes and a working PDF textbook for the course are
in development and a git repo will be shared with
students (feedback and corrections welcome!). The
following references may also be useful:
• Electromagnetics for High-Speed Analog and Digital
Communication Circuits, Ali Niknejad, Cambridge
University Press, 2007.
• RF Microelectronics, 2nd Edition, Behzad Razavi. Pearson
Education, Inc., 2012. This is a very complete reference
and is a great resource for the course.

Ali M. Niknejad University of California, Berkeley EE142/242A

 RF Book In Development
• Direct mirror of course notes
• Work in development, use at
your own risk !
• Look on bCourses for latest
copy. I’ll try to update it on a
weekly basis.
• Please do not share or post on
a public site since I plan to
publish it in the near future.

Ali M. Niknejad University of California, Berkeley EE142/242A

 Prerequisites
• Students directly from 105 to boost interest in radio
frequency circuit techniques
•105 students will definitely have a few extra challenges
since they will not be familiar with all topics. Such topics
and problems will be marked as optional and only
assigned to 242A student.
• 140:Very helpful background, especially differential
amplifiers, feedback, and stability.
• 120:More familiarity with signals and systems but
everything you need is covered in 16AB, 105
• (Frequency Domain and Transfer Functions, Bode)

Ali M. Niknejad University of California, Berkeley EE142/242A

 Course Logistics
• Grading policy:

142 242A
HW 25% 25%
Midterm 25% 25%
Lab 25% 25%
Final 25% 25%

• Exams: No clobbering
• Graduate and undergraduates on a different scale
• Late homeworks get 50% of credit if turned in before solutions are
posted. 25% after solutions posted. These are applied on top of the
grade.

Ali M. Niknejad University of California, Berkeley EE142/242A 6

 Homeworks
• Weekly (mostly) homework assignments
• Extra problems for 242A students
• Easier warmup problems for everyone to get familiar
with material followed by more challenging problems
• Main tool – Keysight Pathwaves Advanced Design
System (ADS), Cadence SpectreRF
• First HW / labs – Overview of tools, equipment, safety
• Discussion section on ADS tutorial
• Submission - bCourses

Ali M. Niknejad University of California, Berkeley EE142/242A

 Labs
• All students are required to complete several hands-
on laboratory assignments:
• Do pre-lab and background reading before attending lab
• Pre-lab invovles doing some calculations and simulations
• Labs are designed to reinforce abstract concepts from
class with real world examples
• You will design and build your own filters, amplifiers,
mixers, and oscillators using SMT (surface mount
tech) components on a PCB
• The first few labs will take much longer ... don’t
despair!

Ali M. Niknejad University of California, Berkeley EE142/242A

 Course Modules

•1: Introduction & Review

•2: Transmission Lines & Smith Chart
•3: Amplifier Design
•4: Distortion
•5: Noise
•6: Mixers
•7: Oscillators & Frequency Synthesis
•8: Power Amplifiers and Transmitters

Ali M. Niknejad University of California, Berkeley EE142/242A 9

 Course Prerequisites

• Basic knowledge of devices (FETs, BJT), I-V relations, C-V relations

• [review] Small signal models and key parameters (gain, bandwidth,
relation to fT) [fT not covered in 105]
• Linear analog circuits (single and multi-stage amplifiers, differential
amplifiers, feedback) [differential not covered in 105]
• Linear systems (impulse response function, frequency domain,
Fourier series and transforms, Laplace transforms)
• Optional: Probability and stochastic processes (noise and noise
transfer functions).

Ali M. Niknejad University of California, Berkeley EE142/242A 10

 Applications
• RF transceivers for wireless communication
• WiFi, Bluetooth, 3G/4G/5G, satellite communication, etc.
• High speed data communication
• High speed links, clock and data recovery, equalization of channel
• Optical communication front-ends
• Radar and Sensors
• Autonomous driving, automatic cruise control
• Precision Instrumentation
• Medical Imaging
• MRI receivers
• Radio Astronomy
• Much of what we “see” is redshifted into the THz, mm-wave and RF
spectrum (evidence of the big bang)
Ali M. Niknejad University of California, Berkeley EE142/242A
 Module 1: Radio Transceiver Block
Diagram
Receiver

Transmitter
Antenna/Front-End

Synthesizer

Ali M. Niknejad University of California, Berkeley EE142/242A 12

 Module 2: Transmission Lines and Smith Chart

• Topics include the interface of high

frequency blocks using transmission
lines, interconnect, and filters.
• Transmission lines in both the time Antenna/Front-End
and frequency domain.
• Design of LC and transmission line
circuits for impedance matching.
• The Smith Chart as a visualization
aid.

Ali M. Niknejad University of California, Berkeley EE142/242A 13

 Module 3A: Wideband and High-
Frequency Amplifiers
• Review of frequency response
• Gain bandwidth product
• Feedback amplifiers
• Applications:
• Fiber optic front-end, Instrumentation, IF gain stages, UWB
• Tuned amplifiers and matching networks
• Review of RLC networks and resonance, Tuned amplifiers, Matching networks,
Capacitive and inductor transformers, Magnetic transformers

• Optimal amplifier design (maximum gain, stability,

matching, noise, linearity)
• Technology: CMOS, BJT, SiGe HBT (MESFET, JFET)

Ali M. Niknejad University of California, Berkeley EE142/242A 14

 Module 3B: (Power) Amplifier Design
• Output power capability
• Power gain, efficiency
• Different classes of operation
• “Linear” Amplifiers: Class A, B, C
• Switching mode amplifiers: Class D

Ali M. Niknejad University of California, Berkeley EE142/242A 15

 Module 4: Distortion in Circuits
• The transmitter Transmitter
spectrum is corrupted by
distortion generated by
active devices
• Source of distortion in electronic circuits
• Device characteristics and large signal models
• Distortion reduction techniques
• Measurement of distortion (harmonic, inter-modulation, cross-
modulation)
• Effect of feedback on distortion
• System distortion specifications
Ali M. Niknejad University of California, Berkeley EE142/242A 16
 Module 5: Noise in Electronic Systems
• The performance of a receiver is fundamentally
limited by the level of noise added to the signal
• Source of noise
• System Noise calculations
• Input/output referred noise
• Noise figure of an amplifier
• Low noise amplifier design (LNA)
• Noise figure of a cascade of amplifiers (or blocks)
• Link budgets
• Applications: Receiver
• LNA for receiver
• Instrumentation
• IF amplifiers
Ali M. Niknejad University of California, Berkeley EE142/242A 17
 Module 6: Mixers and Commutating Circuits
• Frequency translation/conversion in LTV circuits
• Voltage-switching mixers
• Current commutating mixers
• Balanced mixers
• Conversion gain, terminal impedances
• System specifications and transceiver architectures

• Mixers are used to up-

convert (Tx) and down-
concern (Rx) and
modulate the signal
to/from the antenna.
Ali M. Niknejad University of California, Berkeley EE142/242A 18
 Module 7A: Autonomous Circuits:
Oscillators
• Start-Up and Steady-State Analysis
• Amplitude and frequency stability
• Concept of negative resistance
• Oscillator topologies (Colpitts, Hartley, Clapp, Cross-
coupled,...)
• Waveform distortion
• Ring and relaxation oscillators
• Voltage Controlled Oscillators (VCOs)
• Introduction to Frequency Synthesis (PLLs)

Ali M. Niknejad University of California, Berkeley EE142/242A 19

 Module 7B: Frequency Synthesis
• Since carrier frequencies are used for RF modulation, a
transmitter and receiver need to synthesize a precise and stable
reference frequency. Since the reference frequency changes
based on which “channel” is employed, the synthesizer must be
tunable. Think of the tuning “knob” on an radio receiver.
• The reference signal is generated by a voltage-controlled
oscillator (VCO) and “locked” to a much more stable reference
signal, usually provided by a precision quartz crystal resonator
(XTAL).
• A phase-locked loop (PLL) synthesizer is a feedback system
employed to provide the locking and tuning.

Ali M. Niknejad University of California, Berkeley EE142/242A 20

 Overview of
Communication Systems
 Block Diagram of Communication System

• A typical communication system can be partitioned into a

transmitter, a channel, and a receiver.
• In this course we will study the circuits that interface from the
channel to the receiver/transmitter. These circuits are at the
“front-end'” of the transceiver and operate at high frequency.

Ali M. Niknejad University of California, Berkeley EE142/242A

 Source Data
• Most information sources are baseband (BB) in nature, where
we arbitrarily define the bandwidth BW as the highest
frequency of interest. This usually means that beyond the BW
the integrated energy is negligible compared to the energy in
the bandwidth.
• The bandwidth of some common signals:
• High fidelity audio: 20 kHz
• Telephone: 5 kHz
• Uncompressed analog video: ∼ 10 MHz
• 802.11 b/g WLAN: 22 MHz 802.11 n/a/ax 20/40/80/160 MHz
• HD Video (HDMI 1.3+) ~ 340 MHz
• The source is often compressed to conserve bandwidth. Lossless
compression (LZW like Zip files) or lossy (like MP3, JPEG, or MPEG video)
can be used depending on the application.

Ali M. Niknejad University of California, Berkeley EE142/242A

 Data Communication (LAN)
• When sending high speed data through a
cable, we have to deal with several non-
idealities:
• Attenuation, Dispersion, Reflections →
Inter Symbol Interference
• Attenuation is frequency dependent and
causes dispersion, especially at higher
frequencies. The phase response of the line
is also not perfectly linear (constant group
delay), and this causes more dispersion.
• Equalization is used at the source and
Dispersionless Phase Dispersion
Propagation Propagation receiver to compensate for the non-ideality
of the line. But the “channel” has to be
characterized first.

Ali M. Niknejad University of California, Berkeley EE142/242A

 Wireless Propagation
• Wireless links use antennas to convert wave energy on
a transmission line to free-space propagating waveform
(377 ohms in free-space).
• Think of an antenna as a transducer with a given input
impedance, efficiency, gain/directivity. The more gain,
the more directive the antenna. Efficient antennas are
~ λ (free space propagation wavelength).
GTX GRX

PTX PRX

R
Friis transmission equation
  
2
PTX A – antenna aperture
PRX = GTX Aeff , RX = PTX GTX   GRX G – antenna gain
4R 2
 4R  η – radiation efficiency
4Aeff 4Aphys
G= =

2 2

Ali M. Niknejad University of California, Berkeley EE142/242A
 Antenna Gain

• Patch antenna is a resonator that radiates broadside

• It can be implemented on a planar surface, such as a PCB
• Note that it cannot radiate into PCB (due to ground plane),
so it radiates up and has “gain” (more radiation up than
omnidirectional antenna)

Ali M. Niknejad University of California, Berkeley EE142/242A

 Antenna Array

Peak Directivity 16.1 dBi

Peak Gain 15.0 dBi
Peak Realized Gain 14.5 dBi
Radiated Power 35.9 mW
Accepted Power 38.7 mW
Incident Power 40.0 mW
Radiation Efficiency 93%

• An array of antennas have more gain since they power

combine in space preferentially when the radiation is in
phase. If all driven with same power, they will radiate
broadside in phase.
• Note even if we split input power by 4, there’s net gain !

Ali M. Niknejad University of California, Berkeley EE142/242A

 Radiation Patter (Fan)

• The radiation pattern of

an individual element is
“squeezed” in the
direction of the array to
provide more directional
gain.
• By adjusting the phase of
each element, we can
move the solid angle of
peak radiation

Ali M. Niknejad University of California, Berkeley EE142/242A

 Spectrum Regulation
• Since efficient transmission and signal propagation requires an antenna with physical
dimension of ~λ (wavelength), higher frequencies are favorable for portable applications.
For instance, at 3GHz, the free-space wavelength is 10cm (λ = c/f)
• Reason: Physically small antennas have small radiation resistance, which translates into low
efficiency (since the physical resistance can be smaller or comparable to the radiation resistance)
• In the U.S., the FCC regulates spectrum usage [AM band ~ 1000 kHz, FM band ~ 100 MHz,
UHF ~ 500 MHz, Cell phones 800 MHz - 1.9 GHz, WiFi 2.4 GHz (ISM band)]. Emerging
bands: TV bands, 3-10 GHz UWB, 60 GHz.
• Several new bands for 5G mm-wave radios include 24 GHz, 28 GHz, 39 GHz, and other bands (lots
more spectrum)
• Typically each band is further divided into several channels so that spectrum can be
shared. Channel spacing is set by the signal bandwidth.
• While spectrum was traditionally highly regulated and licensed, in the past two decades
we have witnessed an explosion in wireless communication (cordless phones, Bluetooth,
WiFi) using unlicensed bands (such as the ISM -- Industrial, Scientific, and Medical -- in
the 900 MHz and 2.4/5 GHz)

Ali M. Niknejad University of California, Berkeley EE142/242A

 Don’t throw out the Baby with the
bathwater!

• Near/Far Problem: Nearby jammer makes it difficult

to listen to a far away desired signal.
Ali M. Niknejad University of California, Berkeley EE142/242A
 Interference
• In order to detect a signal in the presence of noise, the signal
must meet a certain SNR (signal-noise-ratio) requirement.
Typically this is ~10dB for many simple modulation schemes. For
an analog signal, the ear/eyes can also tolerate a certain amount
of noise (try it!).
• Note that the desired signal is often much weaker than other
signals. In addition to out of band interfering signals, which can
be easily filtered out, we also must contend with strong in-band
interferers. These nearby signals are often other channels in the
spectrum, or other users of the spectrum.
• The dynamic range of a wireless signal is VERY large, on the
order of 80 dB. The signal strength varies a great deal as the user
moves closer or further from a base-station (access point).
• Due to multi-path propagation and shadowing, the signal
strength varies in a time varying fashion.

Ali M. Niknejad University of California, Berkeley EE142/242A

 Multi-Path Propagation
• In addition to contending
with interfering signals
and noise, wireless
propagation is marred by
multi-path propagation
and fading
• There are multiple paths
from source to destination
(LOS and NLOS)
• The delay spread is a
measure of the amount of
time we must wait after
the first RX signal to
process most of the
energy of the signal

Ali M. Niknejad University of California, Berkeley EE142/242A

Transceiver Overview
 Simple AM Transmitters (TX)

• Need an oscillator (carrier frequency) and a mechanism to vary amplitude

of a sinusoidal signal (a multiplier works).
• For digital OOK, this seems trivial (MOS switch for instance), but there are
important issues (such as feedthrough, matching, loss).
• A multiplier, or “mixer”, can also accomplish this task by multiplying the
amplitude signal with a carrier signal.
• For long range transmission, a Power Amplifier (PA) is needed to boost the
signal power.
• In order to provide a stable and precise frequency, a crystal (XTAL)
resonator is used in a phased-locked loop.

Ali M. Niknejad University of California, Berkeley EE142/242A

 Simple AM Receivers (RX)

• A filter is used to “tune” the receiver to the desired band. An amplifier is

usually needed since the signal is too weak to be detected.
• Detection occurs in analog or digital domain (an analog-to-digital “ADC”
converter is needed).
• A mixer can be used to ``down-convert’’ the signal or to directly
demodulate the signal:

Ali M. Niknejad University of California, Berkeley EE142/242A

 Simple FM Transmitter/Receiver

• A voltage controlled oscillator (VCO) is an oscillator that uses a varactor (variable

capacitor) to adjust the oscillation frequency. A ring oscillator can also perform
this task (vary delay per stage by adjusting the current or voltage in the inverter
stages)
• A differentiator converts “FM” into “AM”. In a narrowband of frequencies, a
circuit with a linear frequency response (the skirt of an LC tank) can be used to
perform this task.
• A Limiting Amplifier can be used to remove any residual AM before conversion.

Ali M. Niknejad University of California, Berkeley EE142/242A

 A Modern Receiver

• This is a generic super-heterodyne receiver. There are

several important active and passive blocks in this system.
Passive blocks include the antenna, switches, and filters.
Active building blocks include:
• LNA: Low noise amplifier
• LO: “Local” Oscillator
• VGA: Variable Gain Amplifier (or PGA for programmable gain amplifier)
• ADC: Analog to Digital Converter
• DSP: Digital Signal Processor
Ali M. Niknejad University of California, Berkeley EE142/242A
 A Superheterodyne Transmitter

• This is a generic heterodyne transmitter. In addition to

passive antenna (often shared with receiver through a
switch or duplexer) and filters, we have the following
important active building blocks:
• DAC: Digital to Analog Converter
• Mixer: Up-conversion mixer
• VGA: To select desired output power (not shown)
• LO: Local Oscillator (Generated by a frequency synthesizer)
• PA: Power Amplifier
Ali M. Niknejad University of California, Berkeley EE142/242A
 Received Signal Strength

• The power in communication systems is often measured in the dBm scale, or the
log power measured relative to a 1 mW reference. E.g. a power level of 10 mW
can be expressed as 10 dBm.
• On your laptop or cellular phone, you can often see the signal strength expressed
in dBm units.
• Amplification of weak signals is a major goal of a communication system.
Amplification is not easy since the signals are often only marginally larger than
the intrinsic noise. Additionally, high gain for the interference signals can easily
“rail” our amplifiers unless we carefully filter them out.
• Say your WLAN on your laptop is receiving a signal with strength −70dBm. This
corresponds to a power of P = 1E-7 mW = 1E-10 W=100pW. The voltage on the
antenna can be approximated by

• where, is the antenna impedance.

Ali M. Niknejad University of California, Berkeley EE142/242A

 Receiver Selectivity: Filtering
• A cell phone can work with very smaller signals. For
instance for P = -100 dBm, or P = 1E-13 W, we have

• This is indeed a tiny signal. We need a voltage gain of about

100dBV to bring this signal into the range for baseband
processing.
• Now imagine an interference signal of strength -40dBm, or
about 3mV. This may seem like a small signal, but it
effectively limits the gain of our system to about 1000!
Unless we employ a very high resolution ADC (expensive,
bulky, power hungry), we must filter out this interference.

Ali M. Niknejad University of California, Berkeley EE142/242A

 Filtering in Receivers

Ali M. Niknejad University of California, Berkeley EE142/242A

 Transmitter Spectrum

• The transmitter must amplify the modulated signal and deliver it to

the antenna (or cable, fiber, etc) for transmission over the
communication medium.
• Generating sufficient power in an efficient manner for transmission is
a challenging task and requires a carefully designed power amplifier.
Even the best RF power amplifiers do this with only about 60%
efficiency at RF frequencies.
• The transmitted spectrum is also corrupted by phase noise and
distortion. Distortion products corrupt the spectrum for other users
and must be filtered out.

Ali M. Niknejad University of California, Berkeley EE142/242A