D Flip-flop

Purpose

Implement edge-triggered flip-flop

Library

Control / Logical

Description

../../_images/dflipflop.svg

The D flip-flop sets its output Q to the value of its input D when an edge on the clock input is detected. The behavior is shown in the following truth table:

D

Clk

Q

/Q

0

0

No change

No change

0

1

No change

No change

1

0

No change

No change

1

1

No change

No change

0

Triggering edge

0

1

1

Triggering edge

1

0

The input D is latched, i.e. when a triggering edge in the clock signal is detected the value of D from the previous simulation step is used to set the output. In other words, D must be stable for at least one simulation step before the flip-flop is triggered by the clock signal.

Parameters

Trigger edge

The direction of the edge on which the D input is read.

Initial state

The state of the flip-flop at simulation start.

Probe Signals

D

The input signal D.

Clk

The clock input signal.

Q

The output signals Q.

/Q

The output signals /Q.