11-06-2013, 02:44 PM
SEMESTER EXAMINATIONS FOR CMOS ANALOG AND MIXED SIGNAL DESIGN
CMOS ANALOG1.pdf (Size: 39.81 KB / Downloads: 27)
Answer any five questions
All questions carry equal marks
1.a) What are the three effects that cause the current mirror to be different from the ideal situation?
b) Explain the general principle of the band gap reference and draw a conventional band gap reference.
2.a) Consider the circuit below(figure 1), where a single MOS diode M2 drives two current mirrors M1 and M3. A signal Vsig is present at the drain of M3. What is the effect of Vsig on the signal at the drain of M1 Vout?
b) Derive the transfer function Vsig / Vout for the above circuit in 2(a).
3.a) What are the properties of negative feedback in amplifier?
b) Draw a push-pull inverting CMOS amplifier and explain its characteristics.
4.a) What are the advantages of class AB amplifier over other amplifiers?
b) For the CMOS push pull inverter find the small signal voltage gain AV, -3dB frequency if ID = 200μA, W1/L1= W2/L2 = 5μm/1μm. Cgd1= Cgd2 = 5PF, Cbd1= Cbd2 = 30PF and CL= 10PF.
5. Show that if the voltage gain of an op-amp approaches infinity, the differential input becomes a null port. Assume that the output is returned to the input by means of negative feedback.
6.a) List out the static and dynamic characteristics of a comparator.
b) For the circuit (figure 2) given design a high gain, open-loop comparator having an upper trip point of 1V and a lower trip point of 0V if VOH=2V and VOL=-2V.
7. Design a switched capacitor realization for a first order, high pass circuit with a high frequency gain of -10 and a -3dB frequency of 1 kHz using a clock of 100 kHz.
8. Write a brief note on any one
a) DAC architecture
b) Analog multipliers.