introduction to electronics -...

Ching-Yuan Yang

National Chung Hsing UniversityDepartment of Electrical Engineering

Introduction to Electronics

Read Chapter 1 & Chapter 2, Section 2.1-2.3

Sedra/Smith’s Microelectronic Circuits

1-1 Ching-Yuan Yang / EE, NCHUElectronics (I)

Electronic Circuits (一)

Prof. Ching-Yuan Yang (楊清淵)

Room 823 Electrical Engineering Building

Email: [email protected]

Website: http://web.nchu.edu.tw/~analog/

Text book: Microelectronic Circuits, 5e, by Sedra/Smith (Oxford 2004)

Course Assessment:

15% Assignments

80% Three Term examinations

5% Other

Course Contents:

Introduction (Ch1, Ch2)

Diodes (Ch3)

Bipolar Junction Transistors (Ch5)

MOS Field-Effect Transistors (Ch4)


Brief history of electronics

Identification of the electron by J.J. Thomson late in the 19th

century and the measurement of its electric charge by Robert A. Millikan in 1909.

Invention of vacuum tube in 1906 by Lee De Forest

Invention of the transistor in 1947 by John Bardeen, Walter H. Brattain, and William B. Shockley of the Bell Lab.

Invention of integrated circuits (IC) independently by Jack Kilbyof Texas Instruments in 1958 and by Jean Hoerni and Robert Noyce of Fairchild Semiconductor in 1959.

Discover of Moore's law (1965): The number of transistors per silicon chip doubles every 18 months.


Examples of analog IC

−Gyroscope systemSingle-chip gyroscopic sensor

Tiny

Robust

Lower power

Angular-rate-to-voltage transducer

−BiCMOS process

−Chip area: 3mm × 3mm

−Power: 30mW @ 5V

−Product by Analog Devices, USA


Signal source

A fundamental function of electronic circuits is to process signals.

Signals contain information about a variety of things and activities in our physical world. Example - information about weather: air temperature, humidity, pressure, etc.

To process the information by electronic systems, the signal must first be converted into an electric signal, i.e., a voltage or current, by a device called “transducer”.

A electric signal source can be represented by either (a) Thévenin or (b) Norton forms:


Analog and digital signals

represents the physical signal in the world around us. A analog signal is continuous both in time and magnitude.

is a sequence of numbers. A digital signal is discrete both in time and amplitude.

Analog signal :

Digital signal :

Discretized or digitized signal :

Digital signal can be converted from analog signal. As shown in Figure, at equal intervals along the time axis, the analog signal is measured (sampled).


Analog and digital signals

Binary number system is most commonly used to represent the discretizedsignal because it results in the simplest possible digital signals and circuits.

The digital signals in binary systems need have only two voltage levels, which can be labeled low and high (0 and 1). If we use N binary digits (bits) to represent each sample of the analog signal, then the digitized sample value can be expressed as

where b0, b1, …, bN-1 , denote the N bits and have values of 0 or 1,

b0 = least significant bit (LSB),

bN-1 = most significant bit (MSB).

For example the D corresponding to 15 is 1+2+4+8 , or (1 1 1 1).

0 1 10 1 12 2 2N

ND b b b −−= + + +


Introduction to amplifiers

Amplifier Gains

Ov

I

vA

v≡Voltage gain ( ) (V/V)

Oi

I

iA

i≡Current gain ( ) (A/A)

L O Op

I I I

P v iA

P v i≡ =

load power ( )Power gain ( ) (W/W)

input power ( )

Gains defined above are ratios of similarly dimensioned quantities and thus are dimensionless numbers.Historically, electronic engineers are used to express gain with a logarithmic measure as

v

i

p

A

A

A

=

=

=

Voltage gain in decibels 20 log dB

Current gain in decibels 20 log dB

Power gain in decibels 10 log dB

Power is related to voltage (or current) squared.


Introduction to amplifiers (cont’)

dc power delivered to the amplifier:

Pdc = V1I1 + V2I2

If the power dissipated in the amplifier circuit is denoted Pdissipated, the power-balance equation for the amplifier can be written as

Pdc + PI = PL + Pdissipated

PI : the power drawn from the signal source

PL : the power delivered to the load

It measures how much dc power is converted to the power on the load.

Amplifier power supply

Amplifier efficiency

LP

Pη ≡ ×

dc

100



Amplifier saturation

In order to avoid distorting the output signal waveform, the input signal swing must be kept within the linear range of operation:

Iv v

L Lv

A A− +≤ ≤



Concept of biasing

Practically, an amplifier also exhibits nonlinearities of various magnitudes.

A simple technique for obtaining linear amplification is to biasthe circuit to operate at a point near the middle of the transfer characteristic. The point Q is known as the quiescent point, the dc bias point, or simply the operating point.

( ) ( )

( ) ( )I I i

O O o

v t V v t

v t V v t

= +

= +

( ) ( )o v iv t A v t=

Ov

I

dvA

Qdv=

at


IEEE symbol convention

Total instantaneous signal: iCIncremental instantaneous signal: icDC/Biasing level: IC

Incremental peak level: Ic

C C ci I i= +


Circuit models for amplifiers


Digital logic inverter

The logic inverter is the most basic element in digital circuits.

Noise Margin for high inputs:

Noise Margin for low inputs:

The VTC of an ideal inverter:

NMH = VOH − VIH

NML = VIL − VOL

Voltage transfer characteristic (VTC):


Digital logic inverter – implementation

Basis of transistor-transistor logic (TTL)

Transistor switches


Digital logic inverter – implementation (cont’)

No static current flow

Basis of CMOS logic

Complementary switches


Digital logic inverter – implementation (cont’)

The fastest inverter

Complementary outputs

Basis of Emitter-Coupled Logic (ECL)

Current steering


Operational amplifier

Circuit symbol:

Equivalent circuit of the ideal op amp:

Infinite input impedance

Zero output impedance

Zero common-mode gain

Infinite open loop gain A

Infinite bandwidth


Operational amplifier (cont’)

Inverting closed-loop configuration:



Noninverting closed-loop configuration:



Voltage follower:


Circuit simulation using SPICE

SPICE: Simulation Program with Integrated Circuited Emphasis

An open-source program developed by the U.C. Berkeley (1970s)

Computer programs to simulate the operation of electronic circuits

PSpice is a commercial PC version available from Cadence

Others: ISPice, HSpice, …

It is not our objectively to teach how SPICE works nor the intricacies of using it effectively.

Our objective is twofold:

To describe the models that are used by SPICE to represent the various electronic devices

To illustrate how useful SPICE can be in investigating circuit operation

In this course, ….

SPICE

introduction to electronics -...

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