Analog Electronics - 7BPH5C1 - Syllabus

 III YEAR – V SEMESTER

COURSE CODE: 7BPH5C1

CORE COURSE IX – ANALOG ELECTRONICS

Unit I              SEMICONDUCTOR DIODES AND REGULATED POWER SUPPLIES

Semiconductor – p-n junction diode – rectifiers – half and full wave rectifiers – bridge rectifier – efficiency – ripple factor – R-C and π section filter circuits.

Zener diode – characteristics – voltage regulator – regulated power supply using zener diode.

Unit II             TRANSISTORS AND BIASING

Transistor action – CB, CE & CC modes – comparison – amplifier in CE arrangement – load line analysis – cut – off and saturation  – Relation between α and β – Transistor biasing - base resistor bias - feedback resistor bias - voltage divider bias – JFET – construction and working  -  characteristic parameters.

Unit III           AMPLIFIERS

Single stage amplifier – Phase reversal – DC & AC equivalent circuits – Voltage gain – Classification of amplifiers – Input impedance of an amplifier - RC, transformer, direct coupled amplifiers – Comparison of different types of amplifiers.

Unit IV           OSCILLATORS

Transistor audio power amplifier – Difference between voltage and power amplifiers – Performance quantities of power amplifiers – Classification of power amplifiers – Expression for collector efficiency – Class A amplifier – Push – Pull amplifier.

Feedback principle – Negative and positive feedback – current  gain and voltage gain in negative feedback amplifier – Barkhasan condition for oscillation – damped and undamped oscillations –Hartley, Colpitt and  phase shift Oscillator.

Unit V             OPERATIONAL  AMPLIFIER

Characteristics of an ideal op-amp – virtual ground -  op-amp biasing – Non-inverting & Inverting amplifiers– Applications of op-amp – adder, subtractor, differentiator, integrator.

op-amp signal generators: Phase shift, Hartley, Square wave and triangular wave generators.

Text Books:

1. V.K.Mehta, Principles of Electronics, S.Chand & Co Ltd.,10^th Edition, New Delhi,  2007.
2. R.S.Sedha – Text Book of Applied Electronics, S.Chand & Co Ltd., II Edition, New Delhi,  2004.
3. Electronic Devices and Circuits –  Salivahanan and Suresh Kumar, Mc Graw Hill Edn. New Delhi, 2012

Books for Reference:

1. B.L. Theraja – Basic Electronics – S. Chand & Co, V Edition, New Delhi,  2009.
2. Malvino & Leach – Transistor Approximations – International Publication, New Delhi, – 2000.

Optics and Spectroscopy - 7BPH3C1 Syllabus

II YEAR – III SEMESTER

COURSE CODE: 7BPH3C1

CORE COURSE VI – OPTICS AND SPECTROSCOPY

Unit I              GEOMETRICAL OPTICS

Lens – Spherical aberration in lenses – Methods of minimizing spherical aberration – chromatic aberration in lenses – condition for achromatism of two thin lenses (in and out of contact) – Coma - Aplanatic lens – Eyepieces – Ramsden’s and Huygens’s eyepieces.  Dispersion – Angular and Chromatic dispersion – combination of prisms to produce i)dispersion without deviation ii) deviation without dispersion – Cauchy’s dispersion formula– Direct vision spectroscope – Theory of formation of rainbow.

Unit II             INTERFERENCE

Conditions for interference – colours of thin films – Air wedge – theory – determination of diameter of a thin wire by Air wedge – test for optical flatness – Newton’s rings – Determination of refractive index of a liquid.  Michelson’s Interferometer – theory and its Application (Measurement of wavelength and difference between wavelength of two close lines, thickness of mica sheet) – Jamin’s interferometers – determination of refractive index of gases

Unit III           DIFFRACTION

Fresnel’s  diffraction –Rectilinear propagation of light – zone plate –diffraction at circular aperture – opaque circular disc – Fraunhofer  diffraction at single slit – Double slit – Plane diffraction grating – theory and experiment to determine wavelength – overlapping of spectral lines. Rayleigh’s criterion for resolution – resolving power – resolving power of grating – resolving power of a prism.

Unit IV           POLARISATION

Double refraction – Huygens’s explanation of double refraction in uni axial crystals – Nicol Prism – Nicol Prism as polarizer  and analyzer – Polaroids and their uses – Quarter wave plates and Half wave plates.  Plane, elliptically and circularly polarized light – Production and detection – Optical activity– Fresnel’s explanation of optical activity – Specific rotatory power – determination using Laurent’s half shade polarimeter.

Unit V             SPECTROSCOPY

Microwave and infrared Spectroscopy – Rotation of molecules – Rotational Spectra – The  rigid  diatomic molecules, selection rules – the intensities of spectral lines – Infrared spectroscopy (outlines only) – Raman Spectroscopy – Quantum theory of Raman effect – Classical theory of Raman effect – Molecular Polarisability – pure rotational Raman spectra of linear molecules – vibrational Raman spectra – Applications.

Text Books:

1. Optics and Spectroscopy –     R.Murugeshan, S. Chand and co., 6^th Edition, New Delhi, 2008.
2. A text book of Optics – Subramanyam and Brijlal, S. Chand and co.., 22^nd  Edition, New Delhi 2004.
3. Elements of Spectroscopy – S.L. Gupta, V.Kumar and R.C.Sharma Pragati Prakashan, 13^th Edition, Meerut, 1997

Books for Reference:

1. Optics –  Sathyaprakash, Ratan  Prakashan Mandhir, VII^th Edition,  New Delhi, 1990.
2. Introduction to Molecular Spectroscopy –C.N.Banewell,TMH publishing co. IV Edition,  New Delhi, 2006.
3.  Molecular structure and spectroscopy – G.Aruldhass, PHI Pvt Ltd, , II Edition, New Delhi, 2007.

Notes for IV and V Unit - Left out in the Material

Click HERE to download Notes for IV and V Unit of Digital Electronics 4BPH6C2

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CD – LASER RW Systems

CD stands for Compact Disk and denotes an optical storage medium used to store video, audio and data. CD-ROM disks can be written once and only read thereafter. CD ROM drive uses LASER technology to read data from it.  A semiconductor LASER generates a high intensity light wave of stable wavelength = 780 nm. A lens system is used to direct the LASER towards the disk over approximately 1 micron diameter spot as shown in the figure.

The intensity of the reflected light from metallic reflection layer, received by photo sensors gives the information of binary data stored in CD. There are two different surfaces called land and bit from which reflection occurs. The pit is approximately 0.12 micron deep compared to land and reflected intensities are about 25 % and more than 70 % respectively (Figure b).  

Every time laser beam travels from land to pit or pit to land there is a change in intensity of reflected light.  This change is read as binary digit 1 and a constant intensity reflected light is interpreted as 0. The pit width is such that there is at least 2 and at most 10 zeroes between every 1.  This is achieved by converting every 8-bit byte into a 14-bit value, a process called Eight to Fourteen Modulation (EFM).  Such arrangements make it easy for the read laser to detect bits and synchronization. Data corresponding to a small portion of the track is shown above label in Figure a.

CD-RW

CD-RW or CD-Read Write gives user facility to write and erase data many times. CD-RW uses an active layer of Ag-In-Sb-Te alloy that has a poly crystalline structure making it reflective (reflectivity 25 %). Writing data on disk uses highest power of laser that heats up selected spots to 500°C – 700°C.  At this temperature the chemical structure liquefies losing its polycrystalline structure and on cooling solidifies to an amorphous state that has reduced reflectivity of 15 %. The reading process is like CD-ROM and CD-R that notes the differences in reflectivity of the storage surface.

To reverse the phase or erase data, the laser operates at a lower power setting and heats the active material to nearly 200°C. This reverses the material from its amorphous to its polycrystalline state and then becomes reflective again.  This is illustrated in the following figure.

Flash Memory Notes

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Flash Memory (Memory Stick)

Flash memory storage is a form of non-volatile memory that was born out of a combination of the traditional EPROM and E²PROM.

In essence it uses the same method of programming as the standard EPROM and the erasure method of the E²PROM.

One of the main advantages that flash memory has when compared to EPROM is its ability to be erased electrically. However it is not possible to erase each cell in a flash memory individually unless a large amount of additional circuitry is added into the chip. This would add significantly to the cost and accordingly most manufacturers dropped this approach in favor of a system whereby the whole chip, or a large part of it is block or flash erased.

Today most flash memory chips have selective erasure, allowing parts or sectors of the flash memory to be erased. However any erasure still means that a significant section of the chip has to be erased.

Flash memory is able to provide high density memory because it requires only a few components to make up each memory cell. In Each Flash memory cell consists of the basic channel with the source and drain electrodes separated by the channel about 1 µm long. Above the channel in the Flash memory cell there is a floating gate which is separated from the channel by an exceedingly thin oxide layer which is typically only 100 Å thick. It is the quality of this layer which is crucial to the reliable operation of the memory.

Above the floating gate there is the control gate. This is used to charge up the gate capacitance during the write cycle.

The Flash memory cell functions by storing charge on the floating gate. The presence of charge will then determine whether the channel will conduct or not. During the read cycle a "1" at the output corresponds to the channel being in its low resistance or ON state.

Programming Flash memory

Programming the Flash memory cell involves a process known as hot-electron injection. When programming the control gate is connected to a "programming voltage". The drain will then see a voltage of around half this value while the source is at ground. The voltage on the control gate is coupled to the floating gate through the dielectric, raising the floating gate to the programming voltage and inverting the channel underneath. This results in the channel electrons having a higher drift velocity and increased kinetic energy.

Collisions between the energetic electrons and the crystal lattice dissipate heat which raises the temperature of the silicon. At the programming voltage it is found that the electrons cannot transfer their kinetic energy to the surrounding atoms fast enough and they become "hotter" and scatter further afield, many towards the oxide layer. These electrons overcome the 3.1 eV (electron volts) needed to overcome the barrier and they accumulate on the floating gate. As there is no way of escape they remain there until they are removed by an erase cycle.

The erase cycle for Flash memory uses a process called Fowler-Nordheim tunneling. The process is initiated by routing the programming voltage to the source, grounding the control gate and leaving the drain floating. In this condition electrons are attracted towards the source and they tunnel off the floating gate, passing through the thin oxide layer. This leaves the floating gate devoid of charge.

Generally the erase process is only made to last a few milliseconds. When complete each Flash memory cell in the block is checked to ensure it has been completely erased. If not a second erase cycle is initiated.

Flash memory access

Flash memory is different to most other types of electronic memory in that while reading data can be performed on individual addresses on certain types of flash memory, erase and write activities may only be performed on a block of a Flash memory. A typical block size will be 64, 128, or 256 kB. In order to accommodate this, the low level control software used to drive Flash memories, needs to take account of this if the read and write operations are to be performed correctly.

Flash memory technology is able to provide a very high density form of memory.

Flash Memory Advantages

•         Non-volatile memory
•          Easily portable (e.g. USB memory sticks, camera flash cards, etc)
•          Mechanically robust

Flash Memory Disadvantages

•          Higher cost per bit than hard drives
•          Slower than other forms of memory
•          Limited number of write / erase cycles
•          Data must be erased before new data can be written
•          Data typically erased and written in blocks