Applied Electronics
UNIT-ITransistor: Transistor as an amplifier: low frequency,
single stage and multistage amplifier.Regulated Power Supply:
Capacitor filters for single-phase rectifiers. Application of
3-pinvoltage regulator Ics 78xx/79xx/317/337.
UNIT IIOPAMP: Introduction to operational amplifiers.
Applications of OPAMP: 1) Summingscaling, averaging, integrator and
differentiator; 2) OPAMP as comparator 3) Instrumentation Amplifier
and its applications.
UNIT-IIIDigital Electronics: 1) Combinational circuits:
multiplexers, demultiplexers, decoders,encoders. 2) Flip-flops':
S-R F/F, clocked S-R F/F, D F/F, J-K F/F, T F/F 3)
Counters:Asynchronous (ripple) counter, Asynchronous UP/DOWN
counter, Synchronous counter,Synchronous UP/DOWN counter. 4)
Registers: Serial-in, serial-out; Parallel-in, serial-out;
Serial-in, parallel out; Serial/parallel in, Serial/parallel
out.
UNIT-IVD/A converters: R/ 2R register ladder. D/A converter. A/D
converters: successive approx. A/D converter
UNIT-VMicroprocessor: Concept of microprocessor, software
architecture of 8086, Addressingmodes, Data transfer arithmetic
logical, Jump/Call, String instructions, Writing simpleassembly
language programmers, Technical details of serial and parallel
ports of IBMcompatible PC.
Text/Reference Books1. Millman, Halkias, Basic Electronics, Tata
McGraw-Hill.2. Coughlin and Driscoll, Operational Amplifiers and
Linear Integrated Circuits,Prentice Hall of India.3. Bray B.B.,
8086 486 Intel Microprocessor, Prentice Hall of India.4. Hall, D.,
8086 Microprocessor, Tata McGraw-Hill
Unit-1Transistor and Regulated Power Supply
Q.1 Define Regulator power supply with diagram?AnsA regulated
power supply is an embedded circuit; it converts unregulated AC
into a constant DC. With the help of a rectifier it converts AC
supply into DC. Its function is to supply a stable voltage (or less
often current), to a circuit or device that must be operated within
certain power supply limits. The output from the regulated power
supply may be alternating or unidirectional, but is nearly always
DC (Direct Current).
Q.2 What is rectifier? How to work of single phase half wave
rectifiers with filter capacitor.AnsRectifier circuits may be
single-phase or multi-phase (three being the most common number of
phases). Most low power rectifiers for domestic equipment are
single-phase, but three-phase rectification is very important for
industrial applications and for the transmission of energy as DC .
Single-phase Half-wave rectificationIn half wave rectification of a
single-phase supply, either the positive or negative half of the AC
wave is passed, while the other half is blocked. Because only one
half of the input waveform reaches the output, mean voltage is
lower. Half-wave rectification requires a single diode in a
single-phase supply, or three in a three-phase supply. Rectifiers
yield a unidirectional but pulsating direct current; half-wave
rectifiers produce far more ripple than full-wave rectifiers, and
much more filtering is needed to eliminate harmonics of the AC
frequency from the output.
Q.2 Describe single phase full wave rectifier with diagram?AnsA
full-wave rectifier converts the whole of the input waveform to one
of constant polarity (positive or negative) at its output.
Full-wave rectification converts both polarities of the input
waveform to pulsating DC (direct current), and yields a higher
average output voltage. Two diodes and a center tapped transformer,
or four diodes in a bridge configuration and any AC source
(including a transformer without center tap), Single semiconductor
diodes, double diodes with common cathode or common anode, and
four-diode bridges, are manufactured as single components. Voltage
regulators are found in almost every piece of electronic equipment,
and range from very low voltage types (e.g. 3.3V used for many
microprocessors) up to hundreds of volts as used in some valve
amplifiers and other equipment that relies on high voltages.
Not every voltage needs to be regulated. It is traditional to
supply opamps used in audio with regulated supplies (typically
15V), but this is primarily done to ensure low ripple (100 or
120Hz) and noise. Opamps don't care much if there's noise on the
supply, and they are perfectly happy even if the supply voltages
change a little while they are working. Provided their maximum
operating voltage is not exceeded and the supplies remain high
enough to allow the signal through without distortion, supply
variations will not result in significant output variations.
Q.4 What is voltage regulator? Show the block diagram of the IC
voltage regulator AnsVoltage regulators are found in almost every
piece of electronic equipment, and range from very low voltage
types (e.g. 3.3V used for many microprocessors) up to hundreds of
volts as used in some valve amplifiers and other equipment that
relies on high voltages.
Not every voltage needs to be regulated. It is traditional to
supply opamps used in audio with regulated supplies (typically
15V), but this is primarily done to ensure low ripple (100 or
120Hz) and noise. Opamps don't care much if there's noise on the
supply, and they are perfectly happy even if the supply voltages
change a little while they are working. Provided their maximum
operating voltage is not exceeded and the supplies remain high
enough to allow the signal through without distortion, supply
variations will not result in significant output variations.
However, this is generally considered unacceptable. The supplies
to opamps should be regulated, because no opamp has an infinite
PSRR, and it degrades at high frequencies as the open loop gain
falls due to internal (or external) frequency compensation. In many
cases, a simple zener diode regulator may be sufficient, but these
are inefficient and are considered very 'low tech' by modern
standards. Q.5 How to work 78xx IC in voltage regulator? Show the
pin diagram of 7805 IC.Ans78xx series ICs do not require additional
components to provide a constant, regulated source of power, making
them easy to use, as well as economical and efficient uses of
space. Other voltage regulators may require additional components
to set the output voltage level, or to assist in the regulation
process. Some other designs (such as a switched-mode power supply)
may need substantial engineering expertise to implement. 78xx
series ICs have built-in protection against a circuit drawing too
much current. They have protection against overheating and
short-circuits, making them quite robust in most applications. In
some cases, the current-limiting features of the 78xx devices can
provide protection not only for the 78xx itself, but also for other
parts of the circuit.7805 is a voltage regulator integrated
circuit. It is a member of 78xx series of fixed linear voltage
regulator ICs. The voltage source in a circuit may have
fluctuations and would not give the fixed voltage output. The
voltage regulator IC maintains the output voltage at a constant
value. The xx in 78xx indicates the fixed output voltage it is
designed to provide. 7805 provides +5V regulated power supply.
Capacitors of suitable values can be connected at input and output
pins depending upon the respective voltage levels. Pin Diagram:
7805 Voltage Regulator IC pin diagram, PinOut...
..
Unit-IIOPAMP
Q.1 What is operation amplifier with inverting and non-inverting
terminal. Show the symbolic diagram? Ans Operational amplifier
(op-amp) is a DC-coupled high-gain electronic voltage amplifier
with a differential input and, usually, a single-ended output. In
this configuration, an op-amp produces an output potential
(relative to circuit ground) that is typically hundreds of
thousands of times larger than the potential difference between its
input terminals. Operational amplifiers had their origins in analog
computers, where they were used to do mathematical operations in
many linear, non-linear and frequency-dependent circuits. The
popularity of the op-amp as a building block in analog circuits is
due to its versatility. Due to negative feedback, the
characteristics of an op-amp circuit, its gain, input and output
impedance, bandwidth etc. are determined by external components and
have little dependence on temperature coefficients or manufacturing
variations in the op-amp itself.
Op-amps are among the most widely used electronic devices today,
being used in a vast array of consumer, industrial, and scientific
devices. Many standard IC op-amps cost only a few cents in moderate
production volume; however some integrated or hybrid operational
amplifiers with special performance specifications may cost over
$100 US in small quantities. Op-amps may be packaged as components,
or used as elements of more complex integrated circuits.
The op-amp is one type of differential amplifier. Other types of
differential amplifier include the fully differential amplifier
(similar to the op-amp, but with two outputs), the instrumentation
amplifier (usually built from three op-amps), the isolation
amplifier (similar to the instrumentation amplifier, but with
tolerance to common-mode voltages that would destroy an ordinary
op-amp), and negative feedback amplifier (usually built from one or
more op-amps and a resistive feedback network).
Q.2 Explain characteristics of operation amplifier?Ans Op-amp
characteristics-:1 Ideal op-ampsAn equivalent circuit of an
operational amplifier that models some resistive non-ideal
parameters.
An ideal op-amp is usually considered to have the following
properties:
Infinite open-loop gain G = vout / 'vin Infinite input impedance
Rin, and so zero input current Zero input offset voltage Infinite
voltage range available at the output Infinite bandwidth with zero
phase shift and infinite slew rate Zero output impedance Rout Zero
noise Infinite Common-mode rejection ratio (CMRR) Infinite Power
supply rejection ratio.
These ideals can be summarized by the two "golden rules":
I. The output attempts to do whatever is necessary to make the
voltage difference between the inputs zero. II. The inputs draw no
current.
The first rule only applies in the usual case where the op-amp
is used in a closed-loop design (negative feedback, where there is
a signal path of some sort feeding back from the output to the
inverting input). These rules are commonly used as a good first
approximation for analyzing or designing op-amp circuits.
None of these ideals can be perfectly realized. A real op-amp
may be modeled with non-infinite or non-zero parameters using
equivalent resistors and capacitors in the op-amp model. The
designer can then include these effects into the overall
performance of the final circuit. Some parameters may turn out to
have negligible effect on the final design while others represent
actual limitations of the final performance that must be
evaluated.
2) Real op-amps
Real op-amps differ from the ideal model in various aspectsReal
operational amplifiers suffer from several non-ideal effects:
3) Finite gain Open-loop gain is infinite in the ideal
operational amplifier but finite in real operational amplifiers.
Typical devices exhibit open-loop DC gain ranging from 100,000 to
over 1 million. So long as the loop gain (i.e., the product of
open-loop and feedback gains) is very large, the circuit gain will
be determined entirely by the amount of negative feedback (i.e., it
will be independent of open-loop gain). In cases where closed-loop
gain must be very high, the feedback gain will be very low, and the
low feedback gain causes low loop gain; in these cases, the
operational amplifier will cease to behave ideally.
4) Finite input impedances The differential input impedance of
the operational amplifier is defined as the impedance between its
two inputs; the common-mode input impedance is the impedance from
each input to ground. MOSFET-input operational amplifiers often
have protection circuits that effectively short circuit any input
differences greater than a small threshold, so the input impedance
can appear to be very low in some tests. However, as long as these
operational amplifiers are used in a typical high-gain negative
feedback application, these protection circuits will be inactive.
The input bias and leakage currents described below are a more
important design parameter for typical operational amplifier
applications.
5) Non-zero output impedance Low output impedance is important
for low-impedance loads; for these loads, the voltage drop across
the output impedance effectively reduces the open loop gain. In
configurations with a voltage-sensing negative feedback, the output
impedance of the amplifier is effectively lowered; thus, in linear
applications, op-amp circuits usually exhibit a very low output
impedance indeed. Low-impedance outputs typically require high
quiescent (i.e., idle) current in the output stage and will
dissipate more power, so low-power designs may purposely sacrifice
low output impedance.
6) Input current Due to biasing requirements or leakage, a small
amount of current (typically ~10 nanoamperes for bipolar op-amps,
tens of picoamperes (pA) for JFET input stages, and only a few pA
for MOSFET input stages) flows into the inputs. When large
resistors or sources with high output impedances are used in the
circuit, these small currents can produce large unmodeled voltage
drops. If the input currents are matched, and the impedance looking
out of both inputs are matched, then the voltages produced at each
input will be equal. Because the operational amplifier operates on
the difference between its inputs, these matched voltages will have
no effect. It is more common for the input currents to be slightly
mismatched. The difference is called input offset current, and even
with matched resistances a small offset voltage (different from the
input offset voltage below) can be produced. This offset voltage
can create offsets or drifting in the operational amplifier.
7) Input offset voltage This voltage, which is what is required
across the op-amp's input terminals to drive the output voltage to
zero, In the perfect amplifier, there would be no input offset
voltage. However, it exists in actual op-amps because of
imperfections in the differential amplifier that constitutes the
input stage of the vast majority of these devices. Input offset
voltage creates two problems: First, due to the amplifier's high
voltage gain, it virtually assures that the amplifier output will
go into saturation if it is operated without negative feedback,
even when the input terminals are wired together. Second, in a
closed loop, negative feedback configuration, the input offset
voltage is amplified along with the signal and this may pose a
problem if high precision DC amplification is required or if the
input signal is very small.[nb 2]
8) Common-mode gain A perfect operational amplifier amplifies
only the voltage difference between its two inputs, completely
rejecting all voltages that are common to both. However, the
differential input stage of an operational amplifier is never
perfect, leading to the amplification of these common voltages to
some degree. The standard measure of this defect is called the
common-mode rejection ratio (denoted CMRR). Minimization of common
mode gain is usually important in non-inverting amplifiers
(described below) that operate at high amplification.
9) Power-supply rejection The output of a perfect operational
amplifier will be completely independent from ripples that arrive
on its power supply inputs. Every real operational amplifier has a
specified power supply rejection ratio (PSRR) that reflects how
well the op-amp can reject changes in its supply voltage. Copious
use of bypass capacitors can improve the PSRR of many devices,
including the operational amplifier.
10 Temperature effects All parameters change with temperature.
Temperature drift of the input offset voltage
Q.3Write short note of summing scaling of operation
amplifier?AnsThe Summing Amplifier is a very flexible circuit based
upon the standard Inverting Operational Amplifier configuration. As
its name suggests, the summing amplifier can be used for combining
the voltage present on multiple inputs into a single output
voltage.
We saw previously in the Inverting Operational Amplifier that
the inverting amplifier has a single input voltage, ( Vin ) applied
to the inverting input terminal. If we add more input resistors to
the input, each equal in value to the original input resistor, Rin
we end up with another operational amplifier circuit called a
Summing Amplifier, summing inverter or even a voltage adder circuit
as shown below.summing amplifier formula-
However, if all the input impedances, ( Rin ) are equal in
value, we can simplify the above equation to give an output voltage
of:Summing Amplifier ckt
Q.4 Write short notes of Differentiator operation
amplifier?AnsThe Op-amp Differentiator Amplifier-The basic Op-amp
Differentiator circuit is the exact opposite to that of the
Integrator Amplifier circuit that we looked at in the previous
tutorial. Here, the position of the capacitor and resistor have
been reversed and now the reactance, Xc is connected to the input
terminal of the inverting amplifier while the resistor, R forms the
negative feedback element across the operational amplifier as
normal.
This Operational Amplifier circuit performs the mathematical
operation of Differentiation, that is it produces a voltage output
which is directly proportional to the input voltages rate-of-change
with respect to time. In other words the faster or larger the
change to the input voltage signal, the greater the input current,
the greater will be the output voltage change in response, becoming
more of a spike in shape.
As with the integrator circuit, we have a resistor and capacitor
forming an RC Network across the operational amplifier and the
reactance ( Xc ) of the capacitor plays a major role in the
performance of a Op-amp Differentiator.
Q.5 Write short note of integrating amplifier?AnsThe Op-amp
Integrating Amplifier Operational amplifier can be used as part of
a positive or negative feedback amplifier or as an adder or
subtractor type circuit using just pure resistances in both the
input and the feedback loop. But what if we were to change the
purely resistive ( R ) feedback element of an inverting amplifier
to that of a frequency dependant impedance, ( Z ) type complex
element, such as a Capacitor, C. What would be the effect on the
op-amps output voltage over its frequency range.
By replacing this feedback resistance with a capacitor we now
have an RC Network connected across the operational amplifiers
feedback path producing another type of operational amplifier
circuit commonly called an Op-amp Integrator circuit as shown
below.Op-amp Integrator Circuit
Unit-3
Q.1 Describe the BCD to Decimal encoder?AnsThe BCD-Decimal
decoder converts each BCD code to its decimal equivalent.BCD to
decimal decoders takes a 4 bit BCD as an input and produces 10
outputs to the decimal digits. The technique employed is also used
in developing the 3-line-to-8-line decoder. The logic diagram of a
BCD to decimal decoder using AND gates. When each output goes to
HIGH when its corresponding BCD code is applied at its input.
Decimal to BCD encoder using OR gatesQ.2 Explain multiplexer and
De-multiplexer with the help of truth table and logic
diagrams?AnsMultiplexer-Multiplexer are also known as DATA
SELECTORS. The term 'Multiplexer' means "many into one". MUX is a
combinational logic circuit designed to switch one of several input
lines through to a single common output by the use of a control
signal. Multiplexer operate like very fast acting multiple position
rotary switches connecting or controlling multiple input lines
called "channels" one at a time to the output.Multiplexer is a
method by which multiple analog signals or digitals data streams
are combined into one signal over a shared medium. Schematic symbol
for multiplexer is The Block diagrams of multiplexer with n input
lines, m select signals one output line. if the no. of n input
lines is equal to 2m, the m select lines are required to select one
of the n input lines.
DE-MULIPLEXER-De-multiplexer are also known as DATA
DISTRIBUTORS. The term "de-multiplex" means one into many. A
de-multiplexer is a circuit that has one input and more than one
output. it is used when a circuit to send a signal to one of many
devices, its similar to decoder is used to select among many
devices while a de-multiplexer is used to send a signal among many
devices.Schematic Symbols
The block diagram of de-multiplexer has one input lines, m
select signals and n output signals. the select are used to
determine to which output data input is connected , As the
de-multiplexer take one signal input data line and then switches it
to any one of a no, of individual output lines one at a time. the
de-multiplexer convert a serial data signal at the input to a
parallel data at its output lines. its known as serial to parallel
convertor.BLOCK DIAGRAMS-
Q.3What is distinguish between Encoder and Decoder.AnsEncoder-
An encoder performs the inverse operation of a decoder. hence, the
process perform by encoder is called encoding. so, an encoder is a
combinational logic circuit that converts an active input signal
into a coded output signal.it has n input lines and m output lines,
it encodes this active input to an coded binary with m bits. The
number of outputs is less than the number of inputs. The block
diagrams of an encoder is as fellow:DECODER-A decoder is a
combinational circuit that changes a code into a set of signals. it
is a called a decoder because it does the reverse of encoding.
decoders are simple to design. A decoder is similar to
de-multiplexer but without any data input. A common decoder is line
decoder which takes an n-digit binary no. and decodes it into 2nd
output data lines, such that each output lines will be activated
for only one of the possible combinational of inputs.In digital
electronics, a decoder can take the form of a multiple-input,
multiple-output logic circuit that converts coded input into coded
outputs, where the input and output codes are different. if the no.
of inputs and outputs are equal is greater than the no. of
inputs.
Q.4 What is FLIP-FLOP? Name of all type of flip-flop. Explain
R-S flip-flop?AnsFLIP-FLOP- Flip-flop are the electronics device
used in the digital world for a variety of fields. These are used
to store data temporarily. to multiply or divide, to count
operation, or to receive and transfer information when used
properly. its bi-stable multi-vibrators. Types of flip-flop-:1. R-S
flip flop2. J-K flip flop3. D flip flop4. T flip flop5. Master flip
flop
R-S flip flop-
Q.5 What is D flip flop. Explain with diagram?Ans
Unit-IV
Q.1What is R\2R ladder?Ans An R-2R Ladder is a simple and
inexpensive way to perform digital-to-analog conversion, using
repetitive arrangements of precision resistor networks in a
ladder-like configuration. A string resistor ladder implements the
non-repetitive reference network. R-2R resistor ladder network
(digital to analog conversion, or DAC). A basic R-2R resistor
ladder network is shown in Figure 1. Bit4 MSB (most significant
bit) to Bit0 LSB (least significant bit) are driven from digital
logic gates. Ideally, the bits are switched between 0 volts
(digital 0) and Vref (digital 1). The R-2R network causes the
digital bits to be weighted in their contribution to the output
voltage Vout. In this circuit 5 bits are shown, giving 32 possible
outputs. Depending on which bits are set to 1 and which to 0 the
output voltage (out) will be a stepped value between 0 volts and
(Vref minus the value of the minimum step, Bit0). For a digital
value VAL, of a R-2R DAC of N bits of 0 V/Vref, the output voltage
Vout is: Vout = Vref VAL / 2NIn the example shown, N = 5 and hence
2N = 32. With Vref = 3.3 V (typical CMOS logic 1 voltage), Vout
will vary between 00000, VAL = 0 and 11111, VAL = 31.Minimum
(single step) VAL = 1, we have Vout = 3.3 1 / 32 = 0.1 voltsMaximum
output (11111 VAL = 31, we have Vout = 3.3 31 / 25 = 3.2 volts The
R-2R ladder is inexpensive and relatively easy to manufacture since
only two resistor values are required (or 1, if R is made by
placing a pair of 2R in parallel, or if 2R is made by placing a
pair of R in series). It is fast and has fixed output impedance R.
The R-2R ladder operates as a string of current dividers whose
output accuracy is solely dependent on how well each resistor is
matched to the others. Small inaccuracies in the higher significant
bit resistors can entirely overwhelm the contribution of the less
significant bits.Q.2 Write the short notes on digital to analog
conversion.Ans Figure 1: n-bit R-2R resistor ladderA basic R-2R
resistor ladder network is shown in Figure 1. Bit an-1 MSB (most
significant bit) to Bit a0 LSB (least significant bit) are driven
from digital logic gates. Ideally, the bits are switched between 0
volts (logic 0) and Vref (logic 1). The R-2R network causes the
digital bits to be weighted in their contribution to the output
voltage Vout. In this circuit 5 bits are shown (bits 4-0), giving
(25) or 32 possible analog voltage levels at the output. Depending
on which bits are set to 1 and which to 0, the output voltage
(Vout) will be a corresponding stepped value between 0 volts and (
Vref minus the value of the minimum step, Bit0). The actual value
of Vref (and 0 volts) will depend on the type of technology used to
generate the digital signals. For a digital value VAL, of a R-2R
DAC of N bits of 0V/Vref, the output voltage Vout is:Vout = Vref
VAL / 2NIn the example shown, N = 5 and hence 2N = 32. With Vref =
3.3V (typical CMOS logic 1 voltage), Vout will vary between 00000,
VAL = 0 and 11111, VAL = 31.Minimum (single step) VAL = 1, we
haveVout = 3.3 1 / 32 = 0.1 voltsMaximum output (11111) VAL = 31,
we haveVout = 3.3 31 / 25 = 3.2 voltsThe R-2R ladder is inexpensive
and relatively easy to manufacture since only two resistor values
are required (or 1, if R is made by placing a pair of 2R in
parallel, or if 2R is made by placing a pair of R in series). It is
fast and has fixed output impedance R. The R-2R ladder operates as
a string of current whose output accuracy is solely dependent on
how well each resistor is matched to the others. Small inaccuracies
in the higher significant bit resistors can entirely overwhelm the
contribution of the less significant bits. This may result in
non-monotonic behavior at major crossings, such as from 01111 to
10000. Depending on the type of logic gates used and design of the
logic circuits, there may be transitional voltage spikes at such
major crossings even with perfect resistor values. These can be
filtered, with capacitance at the output node for instance (the
consequent reduction in bandwidth may be significant in some
applications). Finally, the 2R resistance is in series with the
digital output impedance. High output impedance gates (e.g., LVDS)
may be unsuitable in some cases. For all of the above reasons (and
doubtless others), this type of DAC tends to be restricted to a
relatively small number of bits, although integrated circuits may
push the number of bits to 14 or even more, 8 bits or fewer is more
typical.Q.3Explain Successive approximation ADC with block
diagram?AnsA successive approximation ADC is a type of
analog-to-digital converter that converts a continuous analog
waveform into a discrete digital representation via a binary search
through all possible quantization levels before finally converging
upon a digital output for each conversion.Block diagram
Successive Approximation ADC Block DiagramKey DAC =
Digital-to-Analog converter EOC = end of conversion SAR =
successive approximation register S/H = sample and hold circuit Vin
= input voltage Vref = reference voltageQ.3 Show the algorithm of
Successive approximation ADC ?AnsThe successive approximation
Analog to digital converter circuit typically consists of four
chief sub circuits:1. A sample and hold circuit to acquire the
input voltage (Vin).2. An analog voltage comparator that compares
Vin to the output of the internal DAC and outputs the result of the
comparison to the successive approximation register (SAR).3. A
successive approximation register sub circuit designed to supply an
approximate digital code of Vin to the internal DAC.4. An internal
reference DAC that, for comparison with VREF, supplies the
comparator with an analog voltage equal to the digital code output
of the SARin.The successive approximation register is initialized
so that the most significant bit (MSB) is equal to a digital 1.
This code is fed into the DAC, which then supplies the analog
equivalent of this digital code (Vref/2) into the comparator
circuit for comparison with the sampled input voltage. If this
analog voltage exceeds Vin the comparator causes the SAR to reset
this bit; otherwise, the bit is left a 1. Then the next bit is set
to 1 and the same test is done, continuing this binary search until
every bit in the SAR has been tested. The resulting code is the
digital approximation of the sampled input voltage and is finally
output by the SAR at the end of the conversion
(EOC).Mathematically, let Vin = xVref, so x in [-1, 1] is the
normalized input voltage. The objective is to approximately
digitize x to an accuracy of 1/2n. The algorithm proceeds as
follows:1. Initial approximation x0 = 0.2. ith approximation xi =
xi-1 - s(xi-1 - x)/2i.
where, s(x) is the sign-function(sign(x)) (+1 for x 0, -1 for x
< 0). It follows using mathematical induction that |xn - x|
1/2n.As shown in the above algorithm, a SAR ADC requires:1. An
input voltage source Vin.2. A reference voltage source V ref to
normalize the input.3. A DAC to convert the it approximation xi to
a voltage.4. A Comparator to perform the function s(xi - x) by
comparing the DAC's voltage with the input voltage.5. A Register to
store the output of the comparator and apply xi-1 - s(xi-1 -
x)/2i.
Q.4 What is Charge-redistribution successive approximation ADC ?
AnsOne of the most common implementations of the successive
approximation ADC, the charge-redistribution successive
approximation ADC, uses a charge scaling DAC. The charge scaling
DAC simply consists of an array of individually switched
binary-weighted capacitors. The amount of charge upon each
capacitor in the array is used to perform the aforementioned binary
search in conjunction with a comparator internal to the DAC and the
successive approximation register.1. First, the capacitor array is
completely discharged to the offset voltage of the comparator, VOS.
This step provides automatic offset cancellation(i.e. The offset
voltage represents nothing but dead charge which can't be juggled
by the capacitors).2. Next, all of the capacitors within the array
are switched to the input signal, vIN. The capacitors now have a
charge equal to their respective capacitance times the input
voltage minus the offset voltage upon each of them.3. In the third
step, the capacitors are then switched so that this charge is
applied across the comparator's input, creating a comparator input
voltage equal to -vIN.4. Finally, the actual conversion process
proceeds. First, the MSB capacitor is switched to VREF, which
corresponds to the full-scale range of the ADC. Due to the
binary-weighting of the array the MSB capacitor forms a 1:1 charge
divider with the rest of the array. Thus, the input voltage to the
comparator is now -vIN plus VREF/2. Subsequently, if vIN is greater
than VREF/2 then the comparator outputs a digital 1 as the MSB,
otherwise it outputs a digital 0 as the MSB. Each capacitor is
tested in the same manner until the comparator input voltage
converges to the offset voltage, or at least as close as possible
given the resolution of the DAC.Q.5Use with non-ideal analog
circuits?AnsWhen implemented as an analog circuit - where the value
of each successive bit is not perfectly 2^N (e.g. 1.1, 2.12, 4.05,
8.01, etc.) - a successive approximation approach might not output
the ideal value because the binary search algorithm incorrectly
removes what it believes to be half of the values the unknown input
cannot be. Depending on the difference between actual and ideal
performance, the maximum error can easily exceed several LSBs,
especially as the error between the actual and ideal 2^N becomes
large for one or more bits. Since we don't know the actual unknown
input, it is therefore very important that accuracy of the analog
circuit used to implement a SAR ASince we know that binary count
sequences follow a pattern of octave (factor of 2) frequency
division, and that J-K flip-flop multivibrators set up for the
"toggle" mode are capable of performing this type of frequency
division, we can envision a circuit made up of several J-K
flip-flops, cascaded to produce four bits of output. The main
problem facing us is to determine how to connect these flip-flops
together so that they toggle at the right times to produce the
proper binary sequence. Examine the following binary count
sequence, paying attention to patterns preceding the "toggling" of
a bit between 0 and 1:
UNIT-V
Q.1 What is microprocessor ?AnsMicroprocessor is a computer
processor that incorporates the functions of a computer's central
processing unit (CPU) on a single integrated circuit (IC), or at
most a few integrated circuits.[2] The microprocessor is a
multipurpose, programmable device that accepts digital data as
input, processes it according to instructions stored in its memory,
and provides results as output. It is an example of sequential
digital logic, as it has internal memory. Microprocessors operate
on numbers and symbols represented in the binary numeral system.The
integration of a whole CPU onto a single chip or on a few chips
greatly reduced the cost of processing power. The integrated
circuit processor was produced in large numbers by highly automated
processes, so unit cost was low. Single-chip processors increase
reliability as there are many fewer electrical connections to fail.
As microprocessor designs get faster, the cost of manufacturing a
chip (with smaller components built on a semiconductor chip the
same size) generally stays the same.Before microprocessors, small
computers had been implemented using racks of circuit boards with
many medium- and small-scale integrated circuits. Microprocessors
integrated this into one or a few large-scale ICs. Continued
increases in microprocessor capacity have since rendered other
forms of computers almost completely obsolete (see history of
computing hardware), with one or more microprocessors used in
everything from the smallest embedded systems and handheld devices
to the largest mainframes and supercomputers.Q.2) Show pin diagram
of 8086 microprocessor?
Intel 8086 registers
1918171615141312111009080706050403020100(bit position)
Main registers
AHALAX (primary accumulator)
BHBLBX (base, accumulator)
CHCLCX (counter, accumulator)
DHDLDX (accumulator, other functions)
Index registers
0000SISource Index
0000DIDestination Index
0000BPBase Pointer
0000SPStack Pointer
Program counter
0000IPInstruction Pointer
Segment registers
CS0000Code Segment
DS0000Data Segment
ES0000ExtraSegment
SS0000Stack Segment
Status register
----ODITSZ-A-P-CFlags
Q.3 Explain addressing modes of 8086?AnsIn computer programming,
addressing modes are primarily of interest to compiler writers and
to those who write code directly in assembly language. Immediate
Mode The immediate mode is the simplest form of addressing. The
operand is part of the instruction and therefore no memory
reference, other than the instruction, is required to retrieve the
operand. This fast mode is used to define constants or set initial
variable values. Immediate mode has a limited range because it is
restricted to the size of the address field, which for most
instruction sets is small compared to word length.Direct Mode In
direct mode, the address field contains the address of the operand.
It requires a single memory reference to read the operand from the
given location. However, direct mode provides only limited address
space. Indirect Mode Indirect mode address fields contain the
operand's address pointer, which in turn contains the full-length
address of the operand. Unlike direct and immediate addressing,
indirect mode has a large address space but is slower because
multiple memory access is required to find the operand.Register
Mode Register mode is similar to direct mode. The key difference
between the two modes is that the address field of the instruction
refers to a register rather than a memory location. Register
addressing does not have an effective address -- three or four bits
are used as the address field to reference registers.Register
Indirect Mode Similar to indirect addressing, in this mode the
operand is inside a memory cell pointed to by contents of a
register. The register contains the effective address of the
operand. This mode has a large address space, but it's limited to
the width of the registers available to store the effective
address.Displacement Mode Displacement mode consists of three
variations: relative addressing; base register addressing; and
indexing addressing. This mode can be considered a combination of
direct and register indirect addressing. The address holds two
values -- base value and a register that contains an integer
displacement that is added or subtracted from the base to form the
effective address in memory.Stack Mode Stack mode, also known as
implicit addressing, consists of a linear array of locations
referred to as last-in first-out queue. The operand is on the top
of the stack. The stack pointer is a register that stores the
address of top of stack location.Q.4 Distinguish between the serial
port and parallel port of IBM?AnsA serial port is a serial
communication physical interface through which information
transfers in or out one bit at a time. Throughout most of the
history of personal computers, data was transferred through serial
ports to devices such as modems, terminals and various
peripherals.While such interfaces as Ethernet, FireWire, and USB
all send data as a serial stream, the term "serial port" usually
identifies hardware more or less compliant to the RS-232 standard,
intended to interface with a modem or with a similar communication
device.Modern computers without serial ports may require
serial-to-USB converters to allow compatibility with RS 232 serial
devices. Serial ports are still used in applications such as
industrial automation systems, scientific instruments, point of
sale systems and some industrial and consumer products. Server
computers may use a serial port as a control console for
diagnostics. Network equipment (such as routers and switches) often
use serial console for configuration. Serial ports are still used
in these areas as they are simple, cheap and their console
functions are highly standardized and widespread. A serial port
requires very little supporting software from the host system. a
serial port is a serial communication physical interface through
which information transfers in or out one bit at a time. Throughout
most of the history of personal computers, data was transferred
through serial ports to devices such as modems, terminals and
various peripherals.
A parallel port is a type of interface found on computers
(personal and otherwise) for connecting peripherals. In computing,
a parallel port is a parallel communication physical interface. It
is also known as a printer port or Getronics port. It was an
industry de facto standard for many years, and was finally
standardized as IEEE 1284 in the late 1990s, which defined a
bi-directional version of the port. Today, the parallel port
interface is seeing decreasing use because of the rise of Universal
Serial Bus (USB) devices, along with network printing using
Ethernet.The parallel port interface was originally known as the
Parallel Printer Adapter on IBM PC-compatible computers. It was
primarily designed to operate a line printer that used IBM's 8-bit
extended ASCII character set to print text, but could also be used
to adapt other peripherals. Graphical printers, along with a host
of other devices, have been designed to communicate with the
system.Q.5 Show the architecture of the 8086 microprocessor.Ans
8086 employ parallel processing. 8086 contain two processing
unit-the bus interface unit and execution unit. The bus interface
unit is the path that 8086 connects to external devices. The system
bus includes an 8-bit bidirectional data bus for 8086(16 bits for
the 8088), a 20-bit address bus, and the signal needed to control
transfers over the bus. Components in BIU Segment register The
instruction pointer Address generation adder bus control logic
instruction queueComponents in EU Arithmetic logic unit, ALU Status
and control flags General-purpose registers Temporary-operand
registers