11. Increasing fan-out ____________ the propagation delay.
A. increases
B. decreases
C. does not affect
D. exponentially decreases
Answer: A
In the CMOS inverter, increasing the fan-out also increases the propagation delay. Fan-out is a term that defines the maximum number of digital inputs that the output of a single logic gate can feed.
12. Fast gate can be built by keeping ________
A. low output capacitance
B. high on-resistance
C. high output capacitance
D. input capacitance does not affect the speed of the gate
Answer: A
A fast gate can be built by keeping the output capacitance small and by decreasing the on-resistance of the transistor.
13. The transconductance of a bipolar is given by ______________
A. (kT/q)/Ic
B. Ic/(kT/q)
C. (q/KT)/Ic
D. Ic/(q/KT)
Answer: B
Transconductance gm of a bipolar transistor is given by gm = Ic/(kT/q). Transconductance is the electrical characteristic relating the current through the output of a device to the voltage across the input of a device.
14. Transconductance depends on the process.
A. true
B. false
Answer: B
Transconductance gm is independent of the process.
15. gm is ______ on input voltage Vbe.
A. inversely proportional
B. proportional
C. exponentially dependent
D. is not dependent
Answer: C
Transconductance gm is exponentially dependent on input voltage Vbe (base to emitter voltage).
16. gm is _______ to Ic.
A. directly proportional
B. inversely proportional
C. not dependent
D. exponentially proportional
Answer: A
Transconductance gm is directly proportional to Ic, collector current.
17. Transconductance is a __________
A. weak function
B. strong function
C. weak and strong function
D. none of the mentioned
Answer: A
Transconductance gm is a weak function of transistor size.
18. gm of bipolar is less than gm of MOS.
A. true
B. false
Answer: B
Transconductance gm of bipolar is greater than gm of MOS if inputs are controlled by equal amounts of charge.
19. Which of the following is true when inputs are controlled by equal amounts of charge?
A. Cg(MOS) = Cbase(bipolar)
B. Cg(MOS) greater than Cbase(bipolar)
C. Cg(MOS) lesser than Cbase(bipolar)
D. Cs(MOS) lesser than Cbase(bipolar)
Answer: A
Cg(MOS) = Cbase(bipolar) when inputs are controlled by equal amounts of charge, and then gm(bipolar) >> gm(MOS).
20. Which has better I/A?
A. CMOS
B. bipolar
C. nMOS
D. pMOS
Answer: B
Current/Area (I/A. of bipolar is five times better than CMOS and this can be calculated using base resistance and base transit time.
