Traditional fastSPICE tools (e.g., HSIM, UltraSim, NanoSim, FineSim) all make a number of accuracy tradeoffs in order to get higher performance. This generally works very well for digital designs where a 5% to 10% inaccuracy is acceptable and worth 10x-100x+ performance and capacity. High-performance analog and RF circuits require much tighter accuracies in order to get correct behavior let alone accurate performance information. “Analog Mode” or tight tolerance settings in most traditional fastSPICE simulators can get you within 2% to 5%. That’s better but generally not accurate enough, and as you tighten traditional fastSPICE simulators to near-SPICE accuracy, you get near-SPICE (or worse) performance.
Analog FastSPICE is completely different than traditional fastSPICE tools. It makes absolutely no approximations, simplifications, abstractions, etc. It runs the original device equations, so it really gets full SPICE accuracy – down to the specified SPICE noise floor (e.g., reltol – typically 0.1%). The waveforms for every node on every run are identical to those produced by traditional SPICE simulators (e.g., HSPICE and Spectre). The only difference is performance. For multiple-hour and longer runs, Analog FastSPICE is consistently 5x-10x+ faster than traditional SPICE. That means it turns a week run into a day run, a day run into a few-hour run, and a few-hour run into a 30 minute run. Berkeley Design Automation stands behind the 5x-10x performance claim versus any simulator that produces full SPICE accuracy to the noise floor.
Because Analog FastSPICE really is full SPICE accurate, designers can use it for post-layout designs, variation analysis (corners and Monte Carlo), and verifying circuits with package inductance and/or transmission line effects. Analog FastSPICE also has vastly superior convergence which gives it 5x-10x higher effective capacity than traditional SPICE. This means it can converge and run full SPICE accurate transient simulation on circuits that no one would dream of running with traditional SPICE (e.g., full 802.11 transceiver, SerDes, flash, etc.). The tool routinely runs circuits with >1M total elements and >200K transistors.
The most impressive thing about Analog FastSPICE is that it actually works as advertised. It reads standard SPICE netlists, standard SPICE models, requires no special inputs or tuning (it doesn’t even have a facility for block-level tuning), produces standard output waveform files, and is integrated into Cadence Virtuoso ADE. Just plug it in and get the same results 5x-10x faster.
Don’t trust me. Look at what the customers on BDA’s web site have to say. Contact them and ask them. Design teams can contact us and we’ll prove it on their circuits.
Berkeley Design Automation