Google+ VLSI QnA: T Flip Flop

Saturday, 17 May 2014

T Flip Flop

Q.1) Explain T flip flop.

Answer) Toggle flip flop is basically a J_K flip flop with its inputs tied together.

Analyzing the circuit,
I) When CLK = ↓ , T = '0' / '1',
     There is no change in the output.

II) When CLK = '0' , T = '0' / '1',
     There is no change in the output.

III) When CLK = '1' , T = '0' / '1',
       There is no change in the output.

IV) When CLK =  , T = '0',
       There is no change in the output ,as J = '0' and K = '0' .

READ : J-K Flip Flop

V)  When CLK = ↑ , T = '1',
      The output gets toggled, as J = '1' and K = '1'.

Truth table for T flip flop
Truth table for T flip flop

Q.2) Draw the excitation table for T flip flop.

Answer) From the truth table, we can infer the following points.
              When Q retains its state either from '0' to '0' or '1' to '1', T = '0'
              When Q changes its state from '1' to '0' or '0' to '1', T ='1'.

Excitation table for T flip flop
Excitation table for T flip flop

Q.3) Convert J-K flip flip to T flip flop.

Answer) Given flop : J-K flip flop (Output)
               Flop to be derived : T flip flop (Input)

Combined truth table for converting J-K flip flop into T flip flop.
Combined truth table for converting J-K flip flop into T flip flop.

                      K from K-Map simplification                                      
K-Map Simplification

T flip flop using J-K flip flop
T flip flop using J-K flip flop

Q.4) Convert S-R flip flop into T flip-flop.

Answer) Given flip flop : S-R flip flop (Output)
               Flop to be derived : T flip flop (Input)

Combined truth table for converting S-R flip flop into T flip-flop
Combined truth table for converting S-R flip flop into T flip-flop

                        R from K-Map simplification                   S from K-Map simplification                                         K-Map Simplification                    
T flip flop using S-R flip flop.
T flip flop using S-R flip flop.

Q.5) Convert D flip flop to T flip flop.

Answer) Given flop : D flip flop. (Output)
              Flop to be derived : T flip flop (Input)

Combined truth table for converting D flip into T flip flop
Combined truth table for converting D flip into T flip flop

D from K-Map Simplification
K-Map Simplification

T flip flop using D flip flop
T flip flop using D flip flop

Q.6) Convert T flip flop to D flip flop

Answer) Given flop : T flip flop
               Flop to be derived : D flip flop.


Combined truth table for converting T flip flop into D flip flop
Combined truth table for converting T flip flop into D flip flop

T from K-Map Simplification
K-Map Simplification

D flip flop using T flip flop.
D flip flop using T flip flop.

Q.7) Convert T flip flop to S-R flip flop.

Answer) Given flop : T flip flop (Output)
              Flop to be derived : S-R flip flop (Input)

Combined truth table for converting T flip flop into S-R flip flop.
Combined truth table for converting T flip flop into S-R flip flop.

T from K-Map Simplification
K-Map Simplification

S-R flip flop using T flip-flop.
S-R flip flop using T flip-flop.

Q.8) Convert T flip flop into J-K flip flop.

Answer) Given flop : T flip flop (Output).
              Flop to be derived : J-K flip flop (Input)

Combined truth table for converting T flip flop into J-K flip flop.
Combined truth table for converting T flip flop into J-K flip flop.

T from K-Map Simplification
K-Map Simplification

J-K flip flop using T flip flop.

Interesting Fact : Full form of JK in J-K flip flop is Jack Kilby.

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