5ECB0 Electronics I

Area: Electronics

Topics: Semiconductors and PN Junctions · MOSFET · Transistor Amplifiers · Current Mirrors · Differential Amplifiers · Operational Amplifiers · Oscillators and Waveform Generators

Related courses: Electronics II - 5ECC0 · Biopotential and Neural Interface Circuits - 5XCC0 · Photonics - 5XTB0

Carriers

Topic: Semiconductors and PN Junctions

Intrinsic: electron-hole pair generated from thermal energy
Doped: n-type (donor, n) and p-type (acceptor, p) fixed (local) charge, globally neutral

and
and

Current

Drift current: directional, ~E
Diffusion current: ~concentration difference

P-N junction

Topic: Semiconductors and PN Junctions

Equilibrium: diffusion of majority carriers, forming depletion region with E () that cause drift that balance diffusion
Reverse bias: temperature dependent, V independent, drift current
Forward bias: V dependent, diffusion current
Reverse Bias: Capacitors, Forward Bias: Diodes

Small signal

Resistance:
Capacitance:
- Depletion:
- Diffusion:

Op-Amps

Topic: Operational Amplifiers

Inverting

Ideal:
and

Non-Inverting

Ideal:
and

Voltage follower where no resistances on Non-inverting → Amplify Current while keeping the voltage the same.

Difference Amplifiers

Topic: Differential Amplifiers

Difference

Common Mode

Diodes

Topic: Semiconductors and PN Junctions

Bias analysis:

V source = SC
Capacitors = OC

Small Signal Analysis:

I source = OC
V source = SC
Capacitors = SC
Inductance = OC
Diodes = R

Primary goal to analyze diode circuits and precision rectifier.
full wave (bridge) and precision rectifier: and respectively when
half wave rectifier:

MOSFET/MOST

Topic: MOSFET

When we say for example means current is S→G since that’s how charge flows.

Saturation: Fully Turned, behaves as a voltage controlled current source. When Vds > Vov (Vov=Vgs-Vt)
Triode: Partially turned on, behaves as voltage controlled resistor. When Vds < Vov.
For P-Channel just use absolute brackets ||.
Application of voltage onto the Body of MOSFET → can modulated the channel width, as it changes .

Small

Conductance:

: mobility
: oxide capacitance
: process trans-conductance parameter
W, L: width, length of MOST
: overdrive voltage
→ Voltage controlled resistor with small

Tapered channel

Triode:
- Voltage controlled Resistor
edge of saturation

Saturation: when
-Voltage controlled Current source

Channel length modulation:

@ (early voltage):

⇒ Early Voltage

Output resistance:

Body effect:

Amplifier

Topic: Transistor Amplifiers

Channel-length modulation:

Small signal model:

V source: SC
I source: OC

Hybrid- model:

r_o
CM+Body effect

T model:

Body effect:
Maximum swing:
Input resistance:

Configurations

Topic: Transistor Amplifiers

Common source:

Gain:
Add for negative feedback:
Ideal gain:

Very high/inf , high
High V gain
Add CD for low

Common gate:

Ideal:
Real:

Low, controllable impedance matching with low impedance sources (cables…) >< Input severely attenuated
High
cascode amp

Common drain (source follower)

Very high, inf , low, controllable
~1 gain
Last stage for low

Current steering

Topic: Current Mirrors

Load curve: I-V of Q2 ()
When MOSFETS (identical W/L)→Current Mirror:

Cascode (CG + CS):

Common mode:

Differential mode:

Virtual GND is established at D → no bypass C to GND in SSA

→ Current source: → cascode

CMRR:

Summary for EC2

Limiters

Topic: Oscillators and Waveform Generators
[!NOTE] (Passive) Limiter Circuits

amplitude dependent gain
Hard Limiter (clipper): higher amplitude → higher attenuation → distortion
Soft Limiter: less distortion:

(ideal diode),

(ideal diode with voltage source (0.7V))

(ideal diode with voltage source and resistor)

exponential model: where at