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 = (A′·C)·B is 1 for exactly one combination of the inputs. Click that row of the truth table.

F = (A′·C)·B
  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
ABCN1N2G1G2F

For the logic circuit shown, how many of the 8 combinations of the inputs A, B and C give the output F = 1? Find N.

A, B, C → F
N =
3.Medium
ABC000111100101324576

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

F = A′B′ + A′BC′ + A′C + AB′
L =
4.Medium
ABC00011110011001031214150716

Use the Karnaugh map to find the minimal sum-of-products (SOP) form of F(A, B, C) = Σm(0, 2, 4, 5, 6). How many product terms N does it have?

F(A, B, C) = Σm(0, 2, 4, 5, 6)
N =
5.Hard
TQ0​Q0​TQ1​Q1​TQ2​Q2​TQ3​Q3​TQ4​Q4​CLK

A 5-bit ripple (asynchronous) counter is built from flip-flops with a propagation delay of 25 ns each. All outputs must have settled before the next clock edge. Find the maximum clock frequency fmax.

n = 5tpd = 25 ns
fmax = MHz
6.Hard
TQ0​Q0​TQ1​Q1​TQ2​Q2​CLKMOD-5

A synchronous mod-5 counter counts 0, 1, …, 4 and then returns to 0. It starts at 4. Which count Q (in decimal) does it show after 20 clock pulses?

Q0 = 420N = 5
Q =

Answer key

  1. 1. ABC = 011
  2. 2. N = 7
  3. 3. L = 2
  4. 4. N = 2
  5. 5. fmax = 8 MHz
  6. 6. Q = 4

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