EE101A
Circuits I
Jeff Stribling
Stanford University
Fall 2025
J. Stribling
EE101A – Stanford University, Fall 2025
1
Lecture 1
• Course Overview
• Basic Circuit Quantities
• Circuit Abstractions
READINGS:
Lecture Note 0 (on Canvas)
Hambley 1.1-1.3, 1.6
Scherz & Monk 2.2, 2.3, 2.5, 2.7, 2.8, 2.13, 2.16
J. Stribling
EE101A – Stanford University, Fall 2025
2
Electronics Curricula
J. Stribling
Power Electronics
Analog Electronics
Digital Electronics
AC-DC Converter,
DC-DC Converters
CS, CD Amplifiers
CMOS Logic Gates
Nodal Analysis
Superposition,
Thevenin, Norton
Component
Models
V, I, P
KCL, KVL
Passive
Components
R, L, C
EE101A – Stanford University, Fall 2025
Device Models
Active Devices
Diode, MOSFET
Semiconductor
3
About your teaching staff
• Safacan Kok (CA): Master’s student in Electrical Engineering from Singapore and
Turkey. He completed his undergrad at Nanyang Technological University, where
he TAed analog and digital electronics courses. He is also a second time CA for
EE101A. At Stanford, his specialization is analog/mixed-signal circuit design and
high-voltage power electronics, and he has also worked on capacitive sensing
systems for soft robotics. For fun, he enjoys soccer, hiking, and road trips!
• Eli LeChien (CA): Master's student from West Lafayette, Indiana and second-time
EE101 CA. He completed his undergrad at Purdue and has done two Tesla
internships in manufacturing and design. At Stanford, his concentration is controls
& optimization, and he does research in the Smart Sensing Systems lab building
circuitry for oceanographic sensing. Outside of academics, he enjoys spikeball,
lifting weights, and hiking - he's been to about 15 national parks, with Angel's
Landing at Zion being his favorite hike!
J. Stribling
EE101A – Stanford University, Fall 2025
4
About your teaching staff
• Chris Lann (CA): Master’s student from Bellingham, WA. Completed his
undergrad at Stanford last year. He took EE101A in 2023, and has continued along
with Stanford’s analog and RF circuit analysis/design classes. His concentration is
in circuits and has been working at the Aerospace Corporation applying this to
satellite R&D. At Stanford, Chris enjoys hanging out in Lab64, surfing, golf, and
rooting for the Seahawks.
• Elijah Kim (CA): Elijah is a coterm studying EE and CS. He loves building all
sorts of projects from rockets to robots. In his free time, you can catch him hiking,
cooking, and driving a motorized couch around campus. Come chat with him about
engineering clubs, startups, novel computing technologies, and cool spots to
explore on campus.
J. Stribling
EE101A – Stanford University, Fall 2025
5
About your teaching staff
• Jeff Stribling (Lecturer): Local. Very Local. Born at Stanford Hospital. UC
Berkeley EECS undergrad, Stanford Ph.D. (EE). Spent 25 years in telecom before
returning to Stanford, currently running the lab64 Makerspace. Officially Italian
now! Loves puzzles and puzzlehunts, backpacking, and the number 17. And of
course, teaching.
J. Stribling
EE101A – Stanford University, Fall 2025
6
EE101A Weekly Schedule
• Find a partner, and sign up for ONE lab
session by the end of the week.
• Note: Lab 0 is optional but if you do it, it
must be this week (in any lab section that
works)
J. Stribling
EE101A – Stanford University, Fall 2025
7
Syllabus highlights – but read it please!
• Contacts:
• CAs:
Safacan Kok, safacan@stanford.edu
Eli LeChien, lechien@stanford.edu
Chris Lann, clan@stanford.edu
Elijah Kim, elijahkim@stanford.edu
• Lecturer: Dr. Jeff Stribling, stribs@stanford.edu
• Websites:
• Canvas: https://canvas.stanford.edu/courses/212381
• Gradescope: https://www.gradescope.com/courses/1098750
• Ed Discussion: https://edstem.org/us/courses/84108
• Lectures: Tuesdays and Thursdays, 10:30AM-11:50AM
• Books:
th
• Hambley, EE Principles and Applications, 7 ed.
• Sedra & Smith, Microelectronic Circuits, 8th ed.
• Scherz and Monk, Practical Electronics for Inventors, 4th ed.
• Help: Office hours! Review Session! EdDiscussion!
J. Stribling
EE101A – Stanford University, Fall 2025
8
Administrative To Dos
• Read Handouts:
• Lecture Note 0 (a review)
• Prof. David Miller’s math primer
• Prof. Tom Lee’s EE-centric history of radio
• Wye-Delta (or Y-Δ) Transformations
• Find a lab partner and sign up for a laboratory slot
• Training (before attending lab):
• Complete EE Lab Safety Training (w/ quiz)
• Complete Solder Training (w/ quiz)
• Ensure you are auto enrolled in Canvas, Gradescope and EdDiscussion
• Turn on Canvas notifications
J. Stribling
EE101A – Stanford University, Fall 2025
9
Objectives of Electrical Engineering Design
Electromagnetics
Control
Electronics
Gather, store, process, transport
and present INFORMATION
Photonics
Distribute, store, and convert
ENERGY between various forms
Computers
Power
Communication
J. Stribling
Signal Processing
EE101A – Stanford University, Fall 2025
10
Goals for the Course
• Broaden your knowledge base
• Build a foundation
• based on theory fundamentals
• honed by hands on laboratory exercises
• Satisfy a core requirement
• Have fun! Major in EE! Learn to appreciate the number 17!
J. Stribling
EE101A – Stanford University, Fall 2025
11
Charge and the electron
• Electricity (and the electron) powers all electronics
• Discovery (ies) of the electron
• Charge of the electron
• Sign of the electron charge
• Units for charge
J.J. Thomson
Cathode Ray Experiment (1897)
J. Stribling
Robert Millikan
Oil Drop Experiment (1913)
EE101A – Stanford University, Fall 2025
Charles-Augustin de Coulomb
Unit of electric charge (1881)
12
Basic Circuit Quantities
• Current – charge that passes through a cross sectional area of a
conductive path per unit time.
dq ( t )
i (t ) =
dt
t
q ( t ) =  i ( t  ) dt  + q ( t0 )
t0
• Current is measured in amperes (A), or amps.
coulomb
ampere =
second
André-Marie Ampère
Unit of current (1881)
J. Stribling
EE101A – Stanford University, Fall 2025
13
Basic Circuit Quantities
• Voltage – measured between two points A and B, it is the difference in
energy levels for a unit charge located at each point,
or the work needed to move a charge from B to A.
dw
v AB = −  E  d  =
dq
P
• Voltage is a potential difference (like gravitation).
• Voltage is measured in volts (V) and is often referred
to as electric potential or potential difference.
joule
volt =
coulomb
Alessandro Giuseppe Antonio Anastasio Volta
Unit of voltage (1881)
J. Stribling
EE101A – Stanford University, Fall 2025
14
Basic Circuit Quantities
• Power – generally, the rate of energy transfer; here
applied to elements in a circuit.
dw ( t ) dw ( t ) dq ( t )
p (t ) =
=
= v (t ) i (t )
dt
dq
dt
• Power is measured in watts (W).
watt = volt  ampere
t
• Energy – the integral of power. w ( t ) = t p ( t  ) dt  + w ( t0 )
• Energy is measured in joules (J).
James Watt
Unit of power (1889)
0
kg  m 2
joule =
= watt  s = coulomb  volt
2
s
J. Stribling
EE101A – Stanford University, Fall 2025
James Prescott Joule
Unit of energy (1889)
15
Example Currents and Voltages
Example currents:
• 10 kA = lightning strike
• 100 to 800 A = drawn from electric vehicle (EV)
battery while driving
• 200 A = modern home peak current rating
• 40 A = EV charging at home
• 10 A = washer or dryer
• 1 to 5 A = cell phone or laptop charger
• > 0.1 A = current harms a person
• 100 mA = cell phone during typical use
• 10 mA = typical LED (light-emitting diode)
• 10 μA = write/erase current of DRAM memory cell
• 10 fA = smallest current measured by best
instruments in our lab
• 1.6 aA = 10 electrons per second
• 10-25 A = leakage of one Flash memory cell (solidstate drive) = few electrons / year
J. Stribling
Example voltages:
• 100 MV = lightning strike
• 100 kV = high-voltage transmission lines
• 10 kV = static electricity spark
• 400 V = EV car battery
• 110 to 240 V = wall outlets around the
world (root-mean-square AC voltage)
• 5 to 15 V = cell phone or laptop charger
• 10 V = Flash memory write/erase voltage
• 5 V = USB port voltage
• 1.5 V = AAA battery
• 0.5 to 1 V = modern microprocessor
• 50 mV = neuron action potential
• 1 mV = smallest voltage measured by your
DMM
• 100 μV = WiFi antenna
• 100 nV = noise floor of FM antenna
EE101A – Stanford University, Fall 2025
16
Circuits and Systems
• A circuit comprises devices connected by conductors to perform some
function, typically elementary “building blocks”.
• e.g., voltage transformers or signal amplifiers (we will study in EE101A/B)
• A system is a (potentially) complex interconnection of circuits which
interact to achieve an overall objective/function
• e.g., computers, vehicles, robots (we won’t broadly cover systems in EE101A)
J. Stribling
EE101A – Stanford University, Fall 2025
17
Analog vs. Digital
• Analog signals in time (or frequency)
that can take on infinite values of
voltage/current
• Digital signals take on finite
values such as logic “0” or “1”
EE101A
focus: analog
circuits
e.g., music audio out from a smartphone (EE102A/B)
e.g., music stored on a smartphone (EE108)
What about the signals in
(a) and (b) to the right?
J. Stribling
EE101A – Stanford University, Fall 2025
18
AC/DC
• Two types of analog signals we will study in EE101A:
• Direct current (or DC). Examples?
• Alternating current (or AC). Examples?
I (t ) = Im
Im
T
im
i ( t ) = im sin ( t )
1 
f = =
T 2
• Notational convention
AC/DC
Named after a label on
a sewing machine (1973)
• Upper-case letters (including subscript) used for DC signals: VA , I B
• Lower-case letters (including subscript) used for AC signals: va , ib
• Lower-case letters and upper case subscripts) used for AC/DC signals: v A , iB
J. Stribling
EE101A – Stanford University, Fall 2025
19
Circuit Abstractions
• We all love Maxwell’s equations:

E =
0
B = 0
B
E 

E = −
  B = 0  J + 0

t

t


James Clerk Maxwell
Maxwell’s Equations (1861)
• Not practical to study and understand the behavior of circuits based on every
electron according to James, so disappointingly, we will avoid them. Visit (or
enroll in) EE116 for deeper studies around E, B, J, and q.
• In EE101A, we’ll reduce those complex models based on simplified rules and
building blocks through the concept of circuit abstractions.
• Blocks? Resistors, capacitors, inductors, diodes, transistors, supplies
• Rules? Descriptions of behavior in the face of magnetic & electric fields, charges, etc.
J. Stribling
EE101A – Stanford University, Fall 2025
20
Lumped-element Circuit Abstractions
• Assumptions
• Circuits with electrically isolated components connected by
ideal wires
• Elements are very small compared to E&M wavelengths
(meters or more!)
Benjamin Franklin
Pranked us (1747)
Now, we can look at voltages across and currents through various
“lumps” (elements), rather than electric fields and magnetic fields.
We wish to characterize V = f ( I ) or I = f (V ) for some
device. We could plot it on a VI curve (or IV curve)
Notice the current flows from the anode to the cathode.
Which way do the electrons flow? Wha?
J. Stribling
EE101A – Stanford University, Fall 2025
21
Passive Sign Convention (PSC)
• Helps us to maintain a consistent sign convention for power.
• PSC:
• Always label the currents as going into the positive terminal of a device.
• Take V and I as defined above and determine (through some means) their
values, plus P = VI
• Note: It is entirely possible that the values for V and I to turn out negative!
That’s OK!
If P > 0, power is absorbed by the (lumped) element
If P < 0, power is supplied by the (lumped) element
J. Stribling
EE101A – Stanford University, Fall 2025
22
PSC example & Tellegen’s Theorem
+
0.5 V −
3
Battery −
12 A
−
+
+
1V
−
1 V 1 −1 V 2
+
5A
9A
+
0.5 V 4
−
8A
What is the total
power absorbed?
What is the total
power supplied?
What is the total
power in the circuit?
Tellegen’s Theorem stems from the conservation of
energy leading to the conservation of power
J. Stribling
EE101A – Stanford University, Fall 2025
Bernard Tellegen
Tellegen’s Theorem (1952)
23
The Resistor
Our first example of an idealized two-terminal lumped element
+
V
I
I
R
Ohm’s law: V = IR
-
slope = 1/R
V
Resistance is futile, but it is also measured in ohms (Ω)
volt
ohm =
So, what is the power seen in a resistor?
ampere
Georg Simon Ohm
Ohm’s Law (1827)
Unit of resistance (1881)
Resistors can be made from carbon, metal, doped semiconductors, metal
oxides…but in each case must be (nearly) ohmic—with a linear IV curve.
J. Stribling
EE101A – Stanford University, Fall 2025
24
The Resistor, continued
In EE101A labs, we will use
carbon film resistors
Practical considerations:
• R depends on temperature (why?)
• Temperature coefficient of resistivity
(TCR) up to ~ −0.1%/°C
R (T ) = R0 (1 + TCR  T )
• P is limited (why?)
Resistor color code identifies value of R
J. Stribling
EE101A – Stanford University, Fall 2025
25
A Closer Look at the Resistor
Individual electrons are going in all directions.
But with an applied E > 0, they acquire a vd < 0.
−qE
Average velocity: vd =

m
q 2 n
E
Current: I = qnA vd = A
m

 A V 
I =   
   L 
=
1

q
E
τ = scattering time between collisions
~ 0.1 ps → τ = f(T). Why?
m = electron mass
n = electron density
EE 116 will have much more depth on this if you are interested!
J. Stribling
EE101A – Stanford University, Fall 2025
26
Resistance and Resistivity
L
Resistance of an arbitrary block is defined as:
L L
L
R=
=
= Rsh
A HW
W
R
R
H
W
Where ρ is the resistivity of the material (measured in Ωm)



is the sheet resistance and is measured in or
Rsh =
H
J. Stribling

EE101A – Stanford University, Fall 2025
sq
27
Material resistivities
Note the huge
variation in ρ
~1029
Germanium
Paper
J. Stribling
4.7  10−3
Why is there
such variation
in silicon?
1010
EE101A – Stanford University, Fall 2025
28
Conductance and Conductivity
1
• Conductance is defined as the reciprocal of the resistance: G =
R
• Conductance is measured in siemens (S), or less frequently, mhos (℧)
I
Ohm’s law, redux: I = GV
slope = 1/R
G
V
1
• Conductivity is the reciprocal of resistivity:  =

1
S
• Conductivity is measured in
=
m m
J. Stribling
EE101A – Stanford University, Fall 2025
Ernst Werner von Siemens
Unit of conductance (1971)
29
The Independent Voltage Source
Another lumped circuit abstraction
I
I
Independent voltage sources ideally:
+ V
+ V
0
• Have a fixed voltage V = V0 that is
- 0
independent of I.
• Have P = V0 I usually operating such
that P < 0 (supplying power)
Quadrant I: charging
Practically, however:
Quadrant IV: discharging
• V drops for larger | I |
• Models include a series resistance Rs
(more later!)
• I is limited
J. Stribling
EE101A – Stanford University, Fall 2025
I
0
V0
V
I
V0
0
V
30
Thought Experiment
What happens in this circuit?
J. Stribling
EE101A – Stanford University, Fall 2025
31
Independent Voltage Sources, continued
There are two main types of independent voltage source
i(t)I
• DC voltage sources (as shown on slide 29). Independent of I and t
+
-
• E.g., a battery
Vv(t)
0
• AC voltage sources v(t) independent of i but dependent on t.
• E.g., our common wall outlet.
(V )
Consider a sinusoidal AC voltage
source v ( t ) = Vm sin ( t ) across a resistor R
Vm is the peak value or amplitude;
Vpp is the peak-to-peak voltage (2Vm)
What’s the period? Frequency? i(t)? p(t)?
Pavg?
J. Stribling
EE101A – Stanford University, Fall 2025
v(t)
time (ms)
32
Root-mean-square Voltage
If we had a DC voltage source with the same amplitude Vm = 1V as the
previous example, what would be the power absorbed by R? Is it the
same?
No! The root-mean-square voltage (Vrms) is an equivalent DC voltage
level that yields the same Pavg as our (sinusoidal) AC voltage source
2
2
V
V
If Pavg (DC) = Pavg (AC) then rms = m and
Vrms =
R
1
2
Vm
2R
p(t)
True for Sinusoid
sources
AC wall outlets are 120 V (rms), 60 Hz
so Vm = 170 V
AC current is similar: I rms = 12 I m
J. Stribling
Graph
Assumes
R=1Ω
EE101A – Stanford University, Fall 2025
time
2
Vrms
Pavg =
R
33
The Independent Current Source
+
Independent current sources ideally:
• Have a fixed current I = − I 0 that is
I0
V
independent of V.
• Have P = − I 0V usually operating such
that P < 0 (supplying power)
Quadrant III: charging
Practically, however:
Quadrant IV: discharging
• | I | drops for larger |V |
+
• Models include a parallel resistance Rp
(more later!)
I0
V
v(t)
i(t)
• V is limited
There are also AC current sources!
J. Stribling
EE101A – Stanford University, Fall 2025
I
V
-I0
I
0
V
-I0
34