LEPROFESSEURQuestions and answers of various questions asked on LEPROFESSEUR channel.
extract_model_split_partial_clock_gating_arc variable controls whether to split clock gating setup and hold arcs in extracted timing model (ETM). Default value of this variable is FALSE. Setting of this variable affects all formats e.g. synopsys database (.db), liberty (.lib) formats. This variable can be set to either TRUE or FALSE. FALSE: merges all clock gating checks and […]
995 total views, 4 views today
For small state-machines it might be easy by looking at it, however for bigger state machines and interlinked state-machines just by looking may not be easy to fix, there are EDA tools available which can identify stuck states, e.g. Mentor’s autocheck. Also by analyzing code coverage data one can review state machine coverage and identify […]
946 total views, 2 views today
Reconvergence – in simple terms signals are diverging from same end-point in Tx clock domain and going to multiple end-points in Rx clock domain(s). See attached fig. What can we do in this situation? First of all it is an important issue which needs to be carefully reviewed. There can be different approaches to mitigate […]
1,729 total views, 8 views today
Either is good. North American companies prefers Verilog/SystemVerilog and European companies prefer VHDL. Each has it own advantages and disadvantages. One need to know fundamentals of writing a good RTL code. Modern EDA tools can synthesize RTL code written in either language as long as synthesizable constructs are used. I have answered this question on […]
946 total views
This question was asked by “Vazgen Gyoletsyan” on youtube leprofesseur channel. My impression is that modern CDC tools in their reports provide detailed information that can be scripted to know various information related to clock domain crossings in the full chip design. 2,526 total views, 10 views today
2,526 total views, 10 views today
In case of signal crossing from slower clock (source) to faster clock (destination), its a bit easier. Nevertheless it must fulfill minimum pulse width requirements in the receiving faster clock domain. If source clock is minimum 1.5x slower than destination clock, it is safe, one does not need special logic in source domain. In both […]
4,205 total views
When signal is crossing from faster clock domain (source) to slower clock domain (destination), one needs to be very careful, implementation must fulfill minimum pulse width requirements in slower clock. One may implement open loop state machine based solution in faster clock domain or some mechanism which makes sure to fulfill minimum pulse width requirement. […]
3,975 total views, 5 views today
This is probabilistic, please watch metastability lecture for more understanding. Keep in mind this is inherent problem with synchronous design, something more deeper related to device physics. 4,584 total views
4,584 total views
Different technology nodes have different requirements for sync flops. It needs to be characterized sync flops for various parameters before using them in design. Many designers simply use 2 or 3 regular d – flops for synchronization which is not a good design practice. Frequency ratio has nothing to do with the number of sync […]
4,267 total views, 5 views today
There may be violations, we need to see the origin of both clocks, both clocks need to be phase aligned, second, we need to check whether data is passing from faster clock to slower or vice versa. We need to make sure of data stability as well, we need to understand intent of design and […]
4,014 total views, 10 views today
different other techniques may be used, e.g. jog to upper layers, jog to lower layers might not help as it will increase net resistance and hence delay. 6,020 total views, 15 views today
6,020 total views, 15 views today
n-well and p-well are needed to tie to known potential, typically placement of standard cells is done via TAP-LESS library with uniform height (certain advantages such as reduce std cell size, and so pack more cells in a given area), means those cells in same row can share well-ties (done via TAP cells), which can […]
5,964 total views