Digital logic: gates, K-maps & flip-flops worksheet with answers

Free printable Digital logic: gates, K-maps & flip-flops worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
ABCF000?001?010?011?100?101?110?111?

The function F = B′ + C′ + (A·C)′ is 0 for exactly one combination of the inputs. Click that row of the truth table.

F = B′ + C′ + (A·C)′
  1. 1ABC = 000
  2. 2ABC = 001
  3. 3ABC = 010
  4. 4ABC = 011
  5. 5ABC = 100
  6. 6ABC = 101
  7. 7ABC = 110
  8. 8ABC = 111
2.Easy
ABCN1: 1 nsG12 nsG25 nsG38 nsF

The propagation delay of every gate is written under it. Find the worst-case propagation delay tpd from the inputs to the output F.

N1: 1 nsG1: 2 nsG2: 5 nsG3: 8 ns
tpd = ns
3.Medium
ABC000111100101324576

Simplify F = A′BC′ + BC′ + A′B′C to its minimal sum-of-products form. How many literals L does the simplified expression contain?

F = A′BC′ + BC′ + A′B′C
L =
4.Medium
ABC000111100101324576

Simplify F = AB′C + AC + B′C + A′B′ to its minimal sum-of-products form. How many literals L does the simplified expression contain?

F = AB′C + AC + B′C + A′B′
L =
5.Hard
DQ3​Q3​DQ2​Q2​DQ1​Q1​DQ0​Q0​CLKSHIFT

A 4-bit shift register Q₃Q₂Q₁Q₀ holds 0000. At every clock edge the bits shift one place to the right (Q₃ → Q₂ → Q₁ → Q₀, Q₀ is lost) and the serial input enters Q₃. The serial input is 1, 1, 0, 1, 1, 1, 1 at the 7 edges. Give the final state Q = Q₃Q₂Q₁Q₀ as a decimal number.

Q₃Q₂Q₁Q₀ = 00001, 1, 0, 1, 1, 1, 1
Q =
6.Hard
FFQ0​Q0​FFQ1​Q1​FFQ2​Q2​FFQ3​Q3​FFQ4​Q4​FFQ5​Q5​FFQ6​Q6​CLKMOD-100

A 12 kHz clock drives a mod-100 counter. Find the frequency fout of its most significant output, which completes one cycle per counting cycle.

fclk = 12 kHzN = 100
fout = kHz

Answer key

  1. 1. ABC = 111
  2. 2. tpd = 13 ns
  3. 3. L = 5
  4. 4. L = 4
  5. 5. Q = 15
  6. 6. fout = 0.12 kHz

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