VLSI Questions and Answers – BiCMOS Logic Gates

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This set of VLSI Multiple Choice Questions & Answers (MCQs) focuses on “BiCMOS Logic Gates”.

1. The BiCMOS are preferred over CMOS due to ______________
a) Switching speed is more compared to CMOS
b) Sensitivity is less with respect to the load capacitance
c) High current drive capability
d) All of the mentioned
View Answer

Answer: d
Explanation: These are the 3 advantages of BiCMOS over CMOS.
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2. The transistors used in BiCMOS are __________
a) BJT
b) MOSFET
c) Both BJT and MOSFETs
d) JFET
View Answer

Answer: c
Explanation: BiCMOS is a combination of both MOSFET and BJT.

3. The high current driving capability of the BiCMOS is due to __________
a) NMOS in saturation mode
b) PMOS in saturation mode
c) CMOS
d) BJT
View Answer

Answer: d
Explanation: BJT has the high current driving capability.

4. In BiCMOS inverter, the BJT used are __________
a) Only Npn BJT
b) Only Pnp BJT
c) Both npn and pnp BJT
d) Multi emitter npn BJT
View Answer

Answer: a
Explanation: npn BJTs are used in BiCMOS inverter.

5. Which of the following is the drawback of the BiCMOS circuits?
a) Sensitivity is less load capacitance
b) Bipolar transistors are used for driving current to the load capacitance but not for the logic operations
c) Increased fabrication Complexity
d) All of the mentioned
View Answer

Answer: c
Explanation: The other 2 are the merits of BiCMOS, Increased fabrication Complexity is a demerit of BiCMOS circuits.
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6. The Bipolar Transistor is fabricated on __________
a) Same substrate of nMOS
b) N-well in p Substrate
c) P-well in n Substrate
d) Same substrate of pMOS
View Answer

Answer: a
Explanation: BiCMOS is fabricated on the same substrate of nMOS.

7. The n-well created for Bipolar Transistor in BiCMOS is used as __________
a) Substrate
b) Collector
c) Emitter
d) None of the mentioned
View Answer

Answer: b
Explanation: The created nWell is used as Collector region for BiCMOS.

8. The n-well collector is formed by __________
a) Lightly doped n-type epitaxial layer on p-Substrate
b) Heavily doped n-type epitaxial layer on p-Substrate
c) Lightly doped n-type diffused layer on p-Substrate
d) Heavily doped n-type diffused layer on p-Substrate
View Answer

Answer: a
Explanation: To make the doping concentration less than the emitter.

9. The collector contact region is doped with higher concentration of n-type impurities due to __________
a) It creates a depletion region at the contact surface
b) It creates a low conductivity path between collector region and contact
c) It reduces contact resistance
d) It can withstand high voltages as compared to collector region
View Answer

Answer: c
Explanation: The collector contact region is doped with higher concentration of n-type impurities reduces contact resistance.
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10. Which is the proper BiCMOS inverter circuit?
a) vlsi-questions-answers-bicmos-logic-gates-q10a
b) vlsi-questions-answers-bicmos-logic-gates-q10b
c) vlsi-questions-answers-bicmos-logic-gates-q10c
d) vlsi-questions-answers-bicmos-logic-gates-q10d
View Answer

Answer: c
Explanation: None.

11. In the following diagram of BiCMOS, the labels a, b, c, d denote?
vlsi-questions-answers-bicmos-logic-gates-q11
a) A = Collector, B = Base, C = Source, D = Drain
b) A = Emitter, B = Base, C = Drain, D = Source
c) A = Emitter, B = Collector, C = Source, D = Drain
d) A = Collector, B = Emitter, C = Drain, D = Source
View Answer

Answer: c
Explanation: None.

12. What is the work of BJT in BiCMOS?
a) Current controlled Voltage source
b) Voltage controlled Current source
c) Current controlled current source
d) Voltage controlled current source
View Answer

Answer: b
Explanation: The Current Ic and Ie are controlled by base emitter bias voltage.

13. In BiCMOS, the analysis of the operation of BJT is well explained by ___________
a) RC Model
b) Emitter resister model
c) Ebers Moll Model
d) Hybrid model
View Answer

Answer: c
Explanation: None.
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14. The Ebers Moll equivalent circuit of BJT operating in forward active region is?
a) vlsi-questions-answers-bicmos-logic-gates-q14a
b) vlsi-questions-answers-bicmos-logic-gates-q14b
c) vlsi-questions-answers-bicmos-logic-gates-q14c
d) None of the mentioned
View Answer

Answer: b
Explanation: None.

15. The transfer characteristics of BiCMOS inverter is?
a) vlsi-questions-answers-bicmos-logic-gates-q15a
b) vlsi-questions-answers-bicmos-logic-gates-q15b
c) vlsi-questions-answers-bicmos-logic-gates-q15c
d) None of the mentioned
View Answer

Answer: a
Explanation: None.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn