Hardware Interview Questions

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I will be continuosly adding the Electronics/ Hardware/ Analog/ Digital interview questions which i can. I will add the answers real soon. due to time constraints i am not able to do that. If some one wants to contribute to questions or answers you are welcome.

You can reach me at :kothamasu@gmail.com

1) How does a Mosfet works.

2) what are different types of BJT configurations and when do we use them.

3) what is the difference between TTL and CMOS ( even others also like ECL etc).

4) What is noise margin.

5) Which is the most important pin the microcontroller.

6) Explain about Ground Bounce and Vcc Sag.

7) what is EMI and what are different types of it.

8) one question on any kind of sensors you are aware of Ex: hall sensor etc.

9) what is LVDT.

10) how do we select the correct value of decoupling capacitor (or) what is the purpose of using a decoupling capacitor.

11) what is parasitic capacitance & what are the effects of it.

12) what is the difference between microprocessor and micro controller.

13) what are different types of micro processor architectures

14) difference between by pass capacitor and decoupling capacitor

15) how do you select an op amp ( this can apply to other components also)

16) Single ended and Differential signals.

17) How do you decide the layer stack up on PCB.

18) Filter Design : Analog and Digital Filters, different types of filters.

19) what is signal integrity.

20) what is meta stability.

21) Difference between CPLD and FPGA

22) Difference between DDR and DDR2 RAM.

23) what is termination. what are the different types of terminations.

24) When do you need to use an heat sink and how do you decide on that.

25) what is the difference between clock buffer and clock driver.

26) What is Jitter.

27) what is gain bandwidth product

28) Define settling time of op amp.

29) what is slew rate of op amp, define common mode rejection ratio and input offset voltage.

30) what is the difference between static response and dynamic response.

31) what is an integrator and differentiator.

32) define the parameters of an ADC or types of ADC etc.

33) what is sample and hold circuit.

34) what is a comparator.( some questions related to schmitt trigger or positive feed back of op amp)

35) what is Fan Out.

36) Different types of Voltage regulators. ( Linear, Switching etc..)

37) How do you create a basic delay circuit.

38) what is characteristic impedance.

39) what is ringing, undershoot and overshoot of a signal why do they occur and how to reduce them.

40) what is latch up.

41) what are the parameters to be taken into consideration while selecting a mosfet.

42) what are the different modes of operation of mosfet and BJT ( Linear & Switching and Cut off)

43) how do you implement a current source using BJT or MOSFET.

44) what is hysteresis. and what are the advantages and disadvantages of it.

45) what are the effects of vias on PCB.

46) how do you design a voltage to frequency converter.

47) 8051 architecture.

48) Ethernet communication

49) Different types of serial communications ex. I2C

50) Different types of memory devices ( ROM, RAM,SRAM and EEPROM etc)

51) How to select an Opto coupler.

52) what is the main advantage of using a bridge rectifier rather than using a full wave rectifier.

53) what are the applications of zener diode.

54) what are the applications of schottky diode.

55) why do we need a Gate Driver for Mosfet in Switching operations.

56) what is pulse width modulation. give any examples.

57) how does SMPS ( Switch mode power supply works)

58) what does it mean by PID control.

59) what are different types of Flip flops.

60) what is meant by quiescent current and what is the significance of it.

61) How does an instrumentation amplifier differs from normal operational amplifier

62) What are snubbers and how does they protect switching circuits.

63) What is sampling time and how to fix it.

64) What is Rogowski coil and what are its advantages over normal current transformer.

65) What is Ringing, Overshoot and Undershoot how to reduce them.

66) what is a relaxation oscillator.

67) what is hysteresis.

68) what are the different applications of comparators.

69) how does a Unijunction Transistor works.

70) how does programable unijunction transistor works.

71) what are the differences between ASIC, FPGA and CPLD.

72) how to select a network processor.

73) what is the difference between radiated emissions and conducted emissions how to detect and reduce them.

74) what are the different types of negative resistance devices and what are their applications.

75) What is the major application of Zener Diode.

76) When do we use Schottky diode.

77) what are the different types of flip flops.

78) what is the difference between flip flop and latch.

79) what are the types of errors in ADC and DAC's.

80) what is Setup and Hold time of flip flop.

81) what is Race condition in flip flops.

82) What is the difference between RISC and CISC processors.

83) What is tri-state logic.

84) What is the difference between Hardware reset and Software reset.

85) How do you determine the response time of any circuit.[loop response]

86) What is an integrator how do design it.

87) What is a Differentiator design it.

88) What factors will impact the characteristic impedance of the PCB (Dielectric property of insulating material, Seperation between the planes, thickness of the trace.)

89) What are the advantages of using differential signal routing in PCB.

90) How do we make sure that the impedance matching between driver and reciever are maintained.

91) Different types of terminations and their advantages and disadvantages.

92) What is meant by microstip and stripline.

93) How do you decide the placement of components on PCB. i.e. where to route power signals, where to route clock signals, how to route digital signals and analog signals.

94) Why do we need a tie.

95) If suppose you have designed a PCB in which you have selected BGA components what is the care you take when routing. (hint:- Connect all ground pins of BGA IC through thermal Pad).

96) If you have decided to go for only two layer board how do you route power, signal and ground layers.

97) why do we need to route gnd in planes rather than a trace.

98) If we have both analog and digital circuitary on PCB what care we will take while grounding.(How doe we connect those grounds.i.e.through Ferrite bead or Jumper)

99) what does it mean by positive layer and negative layer.

100) What is meant by Solder Mask and Solder Paste.

101) How to decide on what components should be present in top layer and what compnents should be place in bottom layer.

102) what is meant by Reflow Soldering and when do we perform it.

103) what is meant by Wave Soldering what are the advantages and disadvantages of it.

104) what are different types of connectors.(i mean through hole and SMD and what care you need to take while placing them. usually place near to the end of PCB and never route any power signals below it.)

105) what are different types of gerbers.( Hint:-Basic gerber and Extended gerber the difference is in basic gerber all apertures are linked in different files where in in extended gerber all apertures are linked in a single file.)

106) On which side of the board soldering should be done first.

107) what are the different types of dielectric material used in PCB.( Hint:- FR4,HFR4).

108) different kinds of Vias in PCB ( normal via,blind via and burried via).

109) what is pulse width modulation and give some examples where we can use that concept.

110) what are different types of filters(single ended and differential filters you can also think in the way like low pass,high pass, band pass and band reject filters).

111) how does impedance mismatch in signal path effect.

114) why we should not route right angled traces.(right angled traces will act as antenna)

115) why do we call BJT as current controlled device and MOSFET as voltage controlled device.

116) what are active and passive devices.

117) what are the differences between positive and negative feed back in amplifiers.

118) what are the advantages of using darlington pair of transistors.

119) what does it mean by light pipes give some examples where they can be used.

120) what are the different types of semiconductors (Hint:-direct band gap and indirect band gap)

121) what is thyrister and what are the applications of it.

122) Can you explain the applications of Zener diode, Tunnel diode, Schottky diodes.

123) what is the advantge of bridge rectifer when compared to full wave rectifier.(Hint:- The ouput polarity of bridge rectifier is always same irrespective of input polarity, hence when ever we change the supply polarity by mistake the output circuitary will not get effected)

124) what is Clipping and Clamping design a circuit which does the same.

125) why do we need to use heat sinks on certain components. what is the criterion to select a heat sink. (Hint:- Power dissipation is the main culprit)

126) why do we operate a MOSFET or BJT in saturation when we use them for switching purpose.

127) what is quiscent current.

128) what are the different types of oscillators.

129) what is thermal run away.

130) can you exaplain briefly on different types of packages of ICs. ( Ex: TO-92 etc..)

131) what is IGBT and what are the advantages of it.

132) what are different types of MOSFETs ( Hint:- Depletion type and Enhancement type)

133) How do we overcome common mode noise.( explain any preventive measures to be taken to avoid it)

134) what are the different types of noise.

135) What are buffers. what is the importance of using bufferes in any circuit. ( Hint:- Buffers usually will have high input impedance and low output impedance hence it will support to connect more loads at the output and it maintains the input voltage)

136) what are the different types of Analog to Ditial Converters.

137) what are the different types of Digital to Analog Converters.

138) what are the applications of unijunction transistor.

139) Can you give some examples of Voltage to Current converters.

140) What is offset voltage and why do we need to care about it while selecting an Op Amp.

141) What is meant by Thermocouple and how do what are the cares we need to take while carpturing the output of thermocouple and processing it.

142) what are different types of power supplies. (Hint:- Unregulated, regulated,linear, ripple regulated and switching).

143) What is Power Budgeting and How do we perform it. What are the things we will take into consideration while performing power budgeting.

144) what is PLL. Did you any time worked on Voltage controlled oscillators.

145) What is the most important Pin in any microcontroller. (Hint:- reset)

146) what is the difference between serial and parallel communication.

147) what is the difference between RS-232,RS-485 etc...

148) what care you should take while interfacing any microprocessor to memory.

149) what are different types of memory. ( Hint:-Static, dynamic etc.)

150) How do you select a SDRAM.

151) what is EEPROM.

153) Can you explain in brief about the difference between Switches and Bridges. and what are the advantages of each and when to use them.

154) What is JTAG. Did use any time used JTAG to debug any circuit and how it is useful.

155) Did you use any kind of Isolation Amplifiers.

156) How do you generate square wave from sine wave.

157) do you know what is mono stable multi vibrator and astable multi vibrator.

158) How do you provide transient voltage suppression.

159) Did you any time used digital or analog multiplexer.

160) how do you convert serial data to parallel data and vice versa.

161) What do you mean by Charge Pump.

162) what are the considerations to be taken while selecting a micro controller for a specific application.

163) How unity power factor circuit works.

164) what are the different grounding methods available in PCBs.

165) what is space vector control method. how is it different from pulse width modulation.

166) How is schmitt trigger comparator circuit is better than normal comparator circuit.

167) What is the difference between Hardware, Software and Firmware for particular application.

168) What is thermostat and its applications.

169) How to select magnetic shielding for particular components and why do you need shielding.

170) What is feed forward method and how is it helpful in predictive control circuits.

171) What are the different types of switched mode power supplies and what are their power ratings.

172) Why we should sepearte digital and analog grounds in a PCB.

173) How a MOV (metal oxide varistor) or TVS helps in protecting circuits.

174) How do you design sample EMI Filters.

175) What are the major causes for Radiated Emission. (Hint:- clock harmonics, improper terminations etc..)

176) What is wetting voltage.

177) What is dry contact.

178) what happens when a solder is dry solder.

179) what is a chattering contact.

180) What is the difference between hardware reset and software reset.

181) how to you implement line monitoring in any circuit.

182) what are the advantages/dis advantages of using NAND/NOR Flash.

183) What is the difference between SDRAM and DDR RAM.

184) What is memory banking.

185) How to set gain of an amplifier what are the parameters you need to consider while deciding gain.

186) How do you determine the stability of any system.(Hint:- Pole,zero etc..)

187) what is lead/ lag compensation.

188)How to improve/decrease the slew rate of OpAmp.

189) what are the different types of processor architectures (Hint:-Von neumann,Harvard )

190) what is the difference between 8085 and 8086. what are the major changes done to 8086.

191) what is miller effect.

Please Sign my guest book you can provide answers to the above questions or can provide any other questions. Appriciate great help.