FREESCALE PAPER ON 7TH AUGUST The paper was of 90 minutes and had 15 questions each of 10marks. Q1- Design a black box with three ports A,B,C using 5 resistors of 1 ohm each such that RAB=1.5 ohm, RAC=3.5 ohm and RBC=3 ohm. Q2-It was a basic thevenin circuit with three parallel branches containing a current source of 2A current, a resistor of 1 ohm and a battery source of 1V.We were asked to calculate the current in the resistor. Q3-Design a mod-5 counter using JK flip flops with minimum circuitry? Q4-Sythesize the function Y= (AB+CD)E using CMOS? Q5-A general aptitude question with two parts each of 5marks. (a) Related to some matrix…(Could not answer that) (b) Was an easy probability based problem.. Q6-A problem on generating a C-code..Din’t attempt it. Q7-A problem of finding the max frequency with 3 different parts. Each having a different clock skew. Q8-A problem to calculate the propagation delay in a combinational circuit. Q9-A tricky problem on Zener diode with an RC circuit...Had to sketch the voltage waveform across the resistor…… Q10-Data is coming at a rate of 600mhz and is transmitted at 150mhz.Calculate the size of the FIFO required to avoid the overflow if 200 data bits are coming at a time and no data is received until the previous data is completely transmitted? Q11-A microprocessor has an instruction pattern such that the first 3 instructions take 1 clock cycle each, the fourth one takes 2 and the fifth one takes 3 clock cycles. If 1 clock cycle=10ns. Find the MIPS (million instructions per second) of the microprocessor? Q12-A problem on dynamic power dissipation based on the input & output waveforms of a sequential circuit. Q13-Input & output waveforms for a circuit were given. Had to design the circuit to satisfy the conditions. Q14-A very easy opamp based problem to calculate the transfer function of the circuit. Q15-A unusual problem again on power dissipation. Given the power dissipated in each stage of the amplifier blocks.. SOLUTIONS Ans-1:From port A connect two 1 ohm resistors in parallel to point D(say). from point D connect a resistor to port B. And from D connect two restors in series to port C. Ans-2: i=1A Ans-3: Used 3 JK flip-flops with just one additional gate. Ans-4: Used 16 transistors. Ans-10: I got 150 bits. Ans-11: 63.5 MIPS