1. What is internal size of RAM, ROM in 8051?
The Size of RAM : 128 Bytes (earlier or starting version of 8051, eg : AT89S51)
where as the later version of 8051(eg : AT89S52) has 256 Bytes of internal RAM.
The Size of ROM : 4KB on chip and it can be extended upto 64KB using the external
device (eg : EEPROM)
2. What is the difference between i=10 & i==10?
a=10' is used to assign the value of 10 in 'a' variable whereas 'a==10' compare the
value of 'a' variable with 10. Explanation: In "a=10", a is a variable that is initialized
by 10 value because in any programming language "=" stands for assignment operator
which is used to assign the value for any variable.
3. What is silicon BJT circuit?
A bipolar junction transistor (BJT) is a type of transistor that uses
both electrons and electron holes as charge carriers.
4. Compare DTL and TTL families of digital IC
5. What is job of loader in compiler?
Loader is a part of operating system and is responsible for loading executable files
into memory and execute them. It calculates the size of a program (instructions and
data) and creates memory space for it. It initializes various registers to initiate
execution.
6. Draw and explain Architecture of microcontroller 8051?
8051 microcontroller is designed by Intel in 1981. It is an 8-bit microcontroller. It is
built with 40 pins DIP (dual inline package), 4kb of ROM storage and 128 bytes of
RAM storage, 2 16-bit timers. It consists of are four parallel 8-bit ports, which are
programmable as well as addressable as per the requirement. An on-chip crystal
oscillator is integrated in the microcontroller having crystal frequency of 12 MHz.
Let us now discuss the architecture of 8051 Microcontroller.
In the following diagram, the system bus connects all the support devices to the CPU.
The system bus consists of an 8-bit data bus, a 16-bit address bus and bus control
signals. All other devices like program memory, ports, data memory, serial interface,
interrupt control, timers, and the CPU are all interfaced together through the system
bus
7. What is the SPI Protocol?
Serial Peripheral Interface or SPI is a synchronous serial communication protocol that
provides full – duplex communication at very high speeds. Serial Peripheral Interface
(SPI) is a master – slave type protocol that provides a simple and low cost interface
between a microcontroller and its peripherals.
8. Define Zener diode.
A Zener diode is a silicon semiconductor device that permits current to flow in either
a forward or reverse direction.
9. Can you execute bit Array in C language.
https://www.sanfoundry.com/c-program-implement-bit-array/#:~:text=It%20can
%20be%20used%20to,hardware%20to%20perform%20operations
%20quickly.&text=Here%20is%20source%20code%20of,run%20on%20a%20Linux
%20system.
10. Differentiate S-R and J-K flip flops.
The JK flip flop work in the same way as the SR flip flop work. The JK flip flop has
'J' and 'K' flip flop instead of 'S' and 'R'. The only difference between JK flip flop and
SR flip flop is that when both inputs of SR flip flop is set to 1, the circuit produces the
invalid states as outputs, but in case of JK flip flop, there are no invalid states even if
both 'J' and 'K' flip flops are set to 1.
11. Is the following statement valid: int *char = 25?
not valid. you cant use a c++ keyword as a variable name
12. Explain to us the internal structure of UART.
In UART, the mode of transmission is in the form of a packet. The piece that connects the
transmitter and receiver includes the creation of serial packets and controls those physical
hardware lines. A packet consists of a start bit, data frame, a parity bit, and stop bits.
13. Define the terms inductance, resistance and capacitance? Give the units of
measurement of each.
inductance:
the property of an electric conductor or circuit that causes an electromotive force to be
generated by a change in the current flowing.Inductance is measured in units called
henrys. The definition of one henry is simple: One henry is the amount
of inductance necessary to induce one volt when the current in coil changes at a rate
of one ampere per second.
resistance:
Resistance is the opposition that a substance offers to the flow of electric current. unit
of measurement: Ohm
capacitance:
the ratio of the change in an electric charge in a system to the corresponding change in
its electric potential.Capacitance is measured in units called farads (abbreviated F).
14. What is an ideal differential amplifier?
Differential Amplifier is a device that is used to amplify the difference in voltage of
the two input signals. Differential Amplifier is an important building block in
integrated circuits of analog system.
It typically forms input stages of operational amplifiers.
15. Discuss any Quist plot
Nyquist plots are the continuation of polar plots for finding the stability of the closed
loop control systems by varying ω from −∞ to ∞. That means, Nyquist plots are used
to draw the complete frequency response of the open loop transfer function
16. How does a half wave rectifier circuit work?
Half-wave rectifiers transform AC voltage to DC voltage. A halfwave rectifier circuit
uses only one diode for the transformation.
A halfwave rectifier is defined as a type of rectifier that allows only one-half cycle of
an AC voltage waveform to pass while blocking the other half cycle.
17. Explain KVL & KCL with physical significance.
The KVL states that the algebraic sum of the voltage at node in a closed circuit is equal to
zero. The KCL law states that, in a closed circuit, the entering current at node is equal to the
current leaving at the node.
18. Explain the advantages of CMOS compared to TTL.
The advantage of the CMOS over the TTL chips is that the CMOS has a higher
density of logic gates within the same material. TTL chips consume more power as
compared to the power consumed by the CMOS chips even at rest.
19. Sturation Current
The limiting current through an ionized gas or an electron tube such that further
increase of voltage produces no further increase in current.
20. saturation voltage, collector-emitter (VCE(sat))
The voltage between the collector and emitter terminals under conditions of base
current or base-emitter voltage beyond which the collector current remains essentially
constant as the base current or voltage is increased.
21. What is threshold voltage threshold?
The threshold voltage, commonly abbreviated as Vth, of a field-effect transistor is the
value of the gate–source voltage when the conducting channel just begins to connect
the source and drain contacts of the transistor, allowing significant current to flow.
22. Cut-off voltage
In electronics, the cut-off voltage is the voltage at which a battery is considered fully
discharged, beyond which further discharge could cause harm. Some electronic
devices, such as cell phones, will automatically shut down when the cut-off voltage
has been reached.
23. What is characteristic of Ideal OPAMP? Important Interview questions on OPAMP
Ans Characteristic of ideal OPAMP are
1. Infinite voltage gain
2. Zero output impedance
3. infinite input impedance
4. Infinite slew rate
5. Characteristics not drifting with temperature
6. Infinite bandwidth
24. What is an Operational Amplifier (Op-amp)?
An operational amplifier is an integrated circuit that can amplify weak electric signals.
An operational amplifier has two input pins and one output pin. Its basic role is to amplify
and output the voltage difference between the two input pins.
25. Pin Diagram
The pin configuration of the IC 741 operational amplifier is shown below. The op amp 741
pin diagram and the functionality of each pin are explained clearly in the below section.
IC 741 Pin Diagram
Power Supply Pins: Pin 4 and 7
Pin 4 and pin 7 are the negative and positive voltage power supply terminals. The power
which is required for the IC to function is received from both these pins. The voltage level
between these pins can be in the range of 5 – 18V.
Output Pin: Pin 6
The output which is delivered from the IC 741 op amp is received from this pin. The output
voltage that is received at this pin is based on the feedback approach that is used and the
voltage level at the input pins.
When the voltage value at pin 6 is high, this corresponds that output voltage is similar to the
+ve supply voltage. In the same way, when the voltage value at pin 6 is low, this corresponds
that output voltage is similar to the -ve supply voltage.
Input Pins: Pin 2 and Pin 3
These are the input pins for the operational amplifier. Pin 3 is considered as the inverting
input while pin 3 is considered as the non-inverting input pin. When the voltage value at pin 2
>> pin 3 which means that inverting input has a high value of voltage, then the output signal
is low.
In the same way, when the voltage value at pin 3 >> pin 2 which means that non- inverting
input has a high value of voltage, then the output signal is high.
Offset Null Pins: Pin 1 and Pin 5
As before discussed, this operational amplifier has an increased level of voltage gain.
Because of this, even minimal variations in the voltages at both non-inverting and inverting
inputs those are happened because of the abnormalities in the constructional procedure or
other anomaly’s will show an impact on the output.
In order to overcome this, an offset value of the voltage to be applied at pin 1 and pin 5, and
this generally accomplished by a potentiometer.
Not Connected Pin: Pin 8
It is just a pin that is used to fill up the empty pin in the IC 741 Op Amp. It has no connection
with any of the internal or external circuits.
26. Function of Opamp
The fundamental function of an op-amp is to greatly amplify the differential between
the two inputs, and output the result. If input at V(+) is greater than at V(−), the op-
amp will amplify and output a positive signal; if V(−) is greater, the op-amp will
output an amplified negative signal.
27. Electronic oscillator
An electronic oscillator is an electronic circuit that produces a periodic, oscillating
electronic signal, often a sine wave or a square wave or a triangle wave
28. A Negative-feedback amplifier (or feedback amplifier) is an electronic amplifier that
subtracts a fraction of its output from its input, so that negative feedback opposes the
original signal
29.
