mikiah的专栏

A recovery timing check ensures that there is a minimum amount of time between the asynchronous signal becoming inactive and the next active clock edge. In other words, this check ensures that after

Static timing analysis is typically performed at a specific operating condition1.Anoperating conditionis defined as a combination of Process, Voltage and Temperature (PVT). Cell delays and interconn

The cell timing models are intended to provide accurate timing for various instances of the cell in the design environment. The timing models are normally obtained from detailed circuit simulations

1.慢时钟域到快时钟域检查建立时间和保持时间的检查：Here are the clock definitions for our example.create_clock -name CLKM \-period 20 -waveform {0 10} [get_ports CLKM]create_clock -name CLKP \-period 5 -waveform

In some cases, the combinational data path between two flip-flops can take more than one clock cycle to propagate through the logic. In such cases, the combinational path is declared as a multicycle

If a design has both negative-edge triggered flip-flops (active clock edge is falling edge) and positive-edge triggered flip-flops (active clock edge is rising edge), it is likely that half-cycle pa

A hold timing check ensures that a flip-flop output value that is changing does not pass through to a capture flip-flop and overwrite its output before the flip-flop has had a chance to capture its or

The total delay for the logic to propagate through a logic path is referred to as thepath delay. This corresponds to the sum of the delays through the various logic cells and nets along the path. In

The setup check can be mathematically expressed as:Tlaunch + Tck2q + Tdp where Tlaunch is the delay of the clock tree of the launch flip-flop UFF0, Tdp is the delay of the combinational logic data

Skew is the difference in timing between two or more signals, maybe data,clock or both. For example, if a clock tree has 500 end points and has a skew of 50ps, it means that the difference in latenc

A slew rate is defined as a rate of change. In static timing analysis, the rising or falling waveforms are measured in terms of whether the transition is slow or fast. The slew is typically measured i

Every cell has multipletiming arcs. For example, a combinational logic cell, such as and, or, nand, nor, adder cell, has timing arcs from each input to each output of the cell. Sequential cells such

A clock gating check occurs when a gating signal can control the path of a clock signal at a logic cell. An example is shown in Figure 10-10. The pin of the logic cell connected to the clock is called

setting up clocks, specifying IO timing characteristics, and specifying false paths and multicycle paths1.Specifying Clockscreate_clockset_clock_transition：This specification applies only fo

It is possible that certain timing paths are not real (or not possible) in the actual functional operation of the design. Such paths can be turned off during STA by setting these as false paths. A fal

A removal timing check ensures that there is adequate time between an active clock edge and the release of an asynchronous control signal. The check ensures that the active clock edge has no effect be

(1) clockQ1.1什么是同步时钟？时钟频率是整倍数，并且相互之间的相位是固定而且相差可预知的，才可以称得上是同步时钟。其他的都算异步时钟。比如，5M，10M是同步2M，3M一般算异步一个时钟，输出到另一个芯片中，转一圈后，以同样的频率返回到自己的芯片，因为无法确定时钟在另一个芯片里面的latency，所以输出的时钟与输入的时钟算异步一个时钟进到2个PLL，就算那

A clock typically feeds a number of flip-flops. The set of flip-flops being fed by one clock is called itsclock domain. In a typical design, there may be more than one clock domain.A question