ECE 2030d Quiz 4 Spring 2011 Name Student Closed Book No Notes No Calculators 1 2 points Complete the truth table to describe the behavior of this circuit A A 0 0 1 1 out B 2 5 points A transparent latch is constructed as shown at the right using this circuit Complete the timing diagram for the behavior of this latch Assume the output of the latch is initially zero B 0 1 0 1 out IN OUT ENABLE ENABLE IN OUT 3 3 points Two of these transparent latches are used to implement a register flip flop using two phase non overlapping clocks as shown at the right Answer each question below about this flip flop by circling the best answer X IN OUT IN OUT ENABLE ENABLE phi1 phi2 a Is this register transparent YES NO b When can the output Z change value Rising edge of phi2 Falling edge of phi2 multiple times while phi2 is active c The new state of the flip flop is determined by the value of the input X at what time Rising edge of phi1 Falling edge of phi1 Rising edge of phi2 Falling edge of phi2 Z ECE 2030d Quiz 4 Spring 2011 SOLUTION Name Student Closed Book No Notes No Calculators 1 2 points Complete the truth table to describe the behavior of this circuit A A 0 0 1 1 out B B 0 1 0 1 out 1 1 0 out or hold no change etc 2 5 points A transparent latch is constructed as shown at the right using this circuit Complete the timing diagram for the behavior of this latch Assume the output of the latch is initially zero IN OUT ENABLE ENABLE IN OUT when ENABLE 1 OUT IN when ENABLE 0 OUT holds its value 3 3 points Two of these transparent latches are used to implement a register flip flop using two phase non overlapping clocks as shown at the right Answer each question below about this flip flop by circling the best answer X IN OUT IN OUT ENABLE ENABLE phi1 phi2 a Is this register transparent YES NO b When can the output Z change value Rising edge of phi2 Falling edge of phi2 multiple times while phi2 is active c The new state of the flip flop is determined by the value of the input X at what time Rising edge of phi1 Falling edge of phi1 Rising edge of phi2 Falling edge of phi2 Z
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