Introduction to Digital Electronics by John Crowe, Barrie Hayes-Gill | 9780340645703 | 0340645709 | Holooly

Introduction to Digital Electronics [EXP-30805]

154 SOLVED PROBLEMS

Question: 10.6

A 1 Mbit flash memory, organised as 128 K by 8 bits, has a byte write time of 10μs, a flash erase time of 10ms and a verify time of 6 μs. Calculate the total length of time for a complete memory write and then a complete erase.

Verified Answer:

To write a byte of data takes 10μs but each byte s...

Question: 1.1

A circuit contains two variables (i.e. signals), X and Y, which must be OR’d together. How would this operation be shown using Boolean algebra, and how would you describe it verbally?

Verified Answer:

The operation would be spoken as X or Y and writte...

Question: 1.27

A circuit is needed to give an output of 1 when any of its three inputs are 0. Draw the truth table for this circuit and state what single gate could implement this circuit. Then derive its dual and state which gives the most appropriate desription of the circuit’s operation.

Verified Answer:

The truth table, which clearly describes the NAND ...

Question: 9.11

A CMOS inverter has a total inherent drain capacitance at the output of 1 pF before any external load is added. What is the propagation delay for this inverter unloaded? Also, plot a graph of inverter propagation delay versus external load capacitance. Assume that KN=KP=64μA V^-2.

Verified Answer:

Before any load is added (i.e. with 1 pF inherent ...

Question: 9.21

A CMOS version of a three-state logic output buffer is shown in Fig. 9.30. Explain how the circuit operates.

Verified Answer:

With the control line high, a logic 'l' appears at...

Question: 10.3

A PROM of size 4Mbit, organised as 0.5 Mbit by 8 bit, is to be programmed using the CE pulse technique described above. If the CE minimum low pulse width is 100μs then what is the maximum programming time to program all bits? Assume that all other timing parameters can be neglected.

Verified Answer:

A total of 0.5 Mbytes require to be programmed. Si...

Question: 11.5

A schematic for a control circuit consists of four 16 bit D-type based synchronous counters, 20 two-input NAND gates and 24 two-input NOR gates. Estimate the total number of gates required for this design.

Verified Answer:

Gate count for each part: A 16 bit synchronous cou...

Question: 10.7

A single cell of an SRAM uses 20 MΩ load resistors. If the chip operates at 5 V and contains 64 Kbits then what is its power consumption? Assume that the voltage across an MOS transistor when on is 0 V.

Verified Answer:

When one of the inverter outputs is low then curre...

Question: 4.7

A two-bit comparator gives an active-HIGH output, Y, if two two-bit words, A and B, are the same. Give Y in fundamental sum of products form and then use Boolean algebra to show that Y=(A0⊕B0)+(A1⊕B1)

Verified Answer:

Y=\overline{A_{0}} \overline{A_{1}} \over...

Question: 1.18

Another common Boolean expression is the AND-OR-INVERT function, Y=(A·B)+(C·D). Draw out the circuit for this function together with its truth table.

Verified Answer:

This is shown in Fig. 1.9. Note that this function...

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