Rising edge triggering

In this example, NextState is assigned a value only if there is a rising edge on Clk. Thus, four rising-edge-triggered flip-flops (needed to store values 0 through 15) are inferred for reg NextState. 

Here is the behavioral model for the transmitter block TX. This model is a synthesizable model. Rising-edge-triggered flip-flops are inferred for variables TBR, TR, TRE, TBRE, DOUT, CBTT and PA this is because these variables are assigned values under the control of clock CK. 

Here the intention appears to be to store the value of PresentState in a flip-flop (rising-edge-triggered). After synthesis, not only is there a flip-flop for PresentState, there are also four flip-flops for Zout. This is because Zout is assigned under the control of a clock. It may or may not be the intention to generate flip-flops for Zout. If not, then a case statement needs to be written in a separate always statement in which Zout is assigned, this... 

Startpoint f reg (rising edge-triggered flip-flop clocked by dk)... 

The Walt statement will be discussed in the next section, but this statement means.. when the signal CLK changes and that change is from 0 to 1, clock the function of the flip flop. This is a rising edge-triggered flip... 

The state machines in each block are fully s)mchTonous, rising edge-triggered circuits. Each is driven by one phase of a two-phase non-overlap-... 

Of course, a simple leading edge discriminator cannot be used to trigger on such pulses. The amplitude jitter would introduce a timing jitter of the order of the pulse rise time (Fig. 4.1, left). In practice the timing jitter is even larger because any discriminator has an intrinsic delay that depends on the signal slope speed and the amount of overdrive. 

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