Cadence® system design and verification solutions, integrated under our System Development Suite, provide the simulation, acceleration, emulation, and management capabilities.
System Development Suite Related Products A-Z
Cadence® digital design and signoff solutions provide a fast path to design closure and better predictability, helping you meet your power, performance, and area (PPA) targets.
Full-Flow Digital Solution Related Products A-Z
Cadence® custom, analog, and RF design solutions can help you save time by automating many routine tasks, from block-level and mixed-signal simulation to routing and library characterization.
Overview Related Products A-Z
Driving efficiency and accuracy in advanced packaging, system planning, and multi-fabric interoperability, Cadence® package implementation products deliver the automation and accuracy.
Cadence® PCB design solutions enable shorter, more predictable design cycles with greater integration of component design and system-level simulation for a constraint-driven flow.
An open IP platform for you to customize your app-driven SoC design.
Comprehensive solutions and methodologies.
Helping you meet your broader business goals.
A global customer support infrastructure with around-the-clock help.
24/7 Support - Cadence Online Support
Locate the latest software updates, service request, technical documentation, solutions and more in your personalized environment.
Cadence offers various software services for download. This page describes our offerings, including the Allegro FREE Physical Viewer.
Get the most out of your investment in Cadence technologies through a wide range of training offerings.
This course combines our Allegro PCB Editor Basic Techniques, followed by Allegro PCB Editor Intermediate Techniques.
Virtuoso Analog Design Environment Verifier 16.7
Learn learn to perform requirements-driven analog verification using the Virtuoso ADE Verifier tool.
Exchange ideas, news, technical information, and best practices.
The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information.
It's not all about the technlogy. Here we exchange ideas on the Cadence Academic Network and other subjects of general interest.
Cadence is a leading provider of system design tools, software, IP, and services.
I have a general question about the warning "Zero diagonal found in Jacobian"
I use spectre(7.2) to simulate some designs and I get sometimes this warning "Zero diagonal found in Jacobian" (as in the example below), even if the simulation converges and the results seems correct.
what's the effect of a " Zero diagonal found in Jacobian" on the simulation results ?
Is it possible that Jacobian reordering lead to convergence problem or error/innacuracy in the results ?
Thanks for your help,
Best Regards !
**************************************************Stability Analysis `stb': freq = (1 mHz -> 20 GHz)**************************************************Zero diagonal found in Jacobian at `I4.M0:int_s' and `I4.M0:int_s'.Reordering Jacobian.Zero diagonal found in Jacobian at `I4.I89.M13:int_s' and `I4.I89.M13:int_s'.Reordering Jacobian.Trying `homotopy = gmin'.
Maximum value achieved for any signal of each quantity: V: V(net176) = 3.3 VI: I(V13:p) = 4.268 mA stb: freq = 2.154 mHz (2.51 %), step = 159.2 uHz (251 m%) stb: freq = 10 mHz (7.52 %), step = 738.8 uHz (251 m%) stb: freq = 46.42 mHz (12.5 %), step = 3.429 mHz (251 m%) stb: freq = 215.4 mHz (17.5 %), step = 15.92 mHz (251 m%) stb: freq = 1 Hz (22.6 %), step = 73.88 mHz (251 m%) stb: freq = 4.642 Hz (27.6 %), step = 342.9 mHz (251 m%) stb: freq = 21.54 Hz (32.6 %), step = 1.592 Hz (251 m%) stb: freq = 100 Hz (37.6 %), step = 7.388 Hz (251 m%) stb: freq = 464.2 Hz (42.6 %), step = 34.29 Hz (251 m%) stb: freq = 2.154 kHz (47.6 %), step = 159.2 Hz (251 m%) stb: freq = 10 kHz (52.6 %), step = 738.8 Hz (251 m%) stb: freq = 46.42 kHz (57.6 %), step = 3.429 kHz (251 m%) stb: freq = 215.4 kHz (62.7 %), step = 15.92 kHz (251 m%) stb: freq = 1 MHz (67.7 %), step = 73.88 kHz (251 m%) stb: freq = 4.642 MHz (72.7 %), step = 342.9 kHz (251 m%) stb: freq = 21.54 MHz (77.7 %), step = 1.592 MHz (251 m%) stb: freq = 100 MHz (82.7 %), step = 7.388 MHz (251 m%) stb: freq = 464.2 MHz (87.7 %), step = 34.29 MHz (251 m%) stb: freq = 2.154 GHz (92.7 %), step = 159.2 MHz (251 m%) stb: freq = 10 GHz (97.7 %), step = 738.8 MHz (251 m%)Gain margin = 40.6864 dB at frequency = 642.509 MHz.Phase margin = 86.7804 Deg at frequency = 12.8495 MHz.
Hi isazulkcIt is possible that such messages might lead to inaccurate simulation results. Would you please retry the simulation using the latest version of spectre (22.214.171.1245.isr11) to see if the messages still appear?Best regardsQuek
In reply to Quek:
I'm using now Spectre 126.96.36.1990.isr16. With this version of Spectre there is no more jacobian warnings with Spectre simulator (at least in the ones I have done so far), but it still appear during some AMS simulations.<
In reply to isazulkc:
Hi KC"ncsim" executable used in AMS simulations comes from INCISIVE package and not MMSIM package. MMSIM package is only for spectre/ultrasim simulations. You can also upgrade your INCISIVE package to the latest 12.1 version to see if it can resolve your problem.Best regardsQuek