How do you overcome setup and hold time violations?

How do you overcome setup and hold time violations?

For hold time violations:

1. Skew the clock to the start/endpoint (reverse of how to fix setup) to make the endpoint clock arrive earlier.
2. Insert cells along the path to increase the propogation time (insert chains of buffers)
3. Reduce the drive strength of cells on the path to make the transition time increase.

How do you fix setup and hold violations in physical design?

8 Ways To Fix Setup violation:

1. Adding inverter decreases the transition time 2 times then the existing buffer gate.
2. As such cell delay of 1 buffer gate ≈ cell delay of 2 Inverter gate.
3. So stage delay (cell delay + wire delay) in case of single buffer < stage delay in case of 2 inverter in the same path.

How do I fix setup time violation in VLSI?

9. Improve the clk->q delay of launching flip-flop: A flip-flop with less clk->q delay will help meeting a violating setup timing path.

1. Improving transition at flip-flops clock pin.
2. Choosing a flip-flop of high drive strength.
3. Replacing the flip-flop with a flip-flop of same drive strength, but lower Vt.

Why do setup violations occur?

Setup violation occurs when data-path is slowly compared to the clock captured at capture flop. With this thing in mind, various approaches are there to fix the setup.

What causes hold time violation?

Hold time is defined as the minimum amount of time AFTER the clock’s active edge during which the data must be stable. Any violation in this required time causes incorrect data to be latched and is known as a hold violation.

How to fix setup and hold timing violations in FPGA?

This answer is more geared to an ASIC than an FPGA, but some will still apply. To address setup time violations, you can: Use larger/stronger cells to drive paths with high capacitance, which can reduce the time needed to transition on sluggish net.

When to fix a setup and hold violation?

In general, hold time will be fixed during back-end work (during PNR) while building clock tree. If u r a front-end designer, concentrate on fixing setup time violations rather than hold violations.

How to reduce clock frequency in a FPGA?

Insert retiming flops on the path, if the design will allow for it (try to do an operation in two clock cycles instead of one) Reduce the overall clock frequency.

How to fix setup and hold violation in VLSI?

Adding buffer / Inverter pairs /delay cells to the data path helps to fix the hold violation. Note: The hold violation path may have its start point or end point in other setup violation paths. So we have to take extra care before adding the buffer/delay.