OmegaSim™ AMS Analog/Mixed-Signal Fast-SPICE Simulator
Overview
Nascentric’s OmegaSim™ AMS combines the best of Fast-SPICE and traditional SPICE simulators for high-speed verification of mixed analog/digital designs. It is the industry’s first multi-threaded, mixed analog/digital Fast-SPICE simulator to handle designs in excess of tens of millions of transistors, parasitic capacitors, and resistors. It offers a 10X performance improvement over competing Fast-SPICE tools, plus it has comparable accuracy to Berkeley SPICE or its commercial eqivalents.
In the past, designers had to choose between the performance of Fast-SPICE and the accuracy of Berkeley SPICE and its commercial equivalents. Today, OmegaSim AMS provides the best of both worlds – the highest Fast-SPICE performance in the industry with traditional SPICE accuracy.
Background
Fast-SPICE was originally created to handle larger circuits, primarily custom digital and memories, where speed was more important than accuracy. For larger, mixed-signal designs, however, Fast-SPICE tools did not often have enough accuracy to handle the more sensitive analog portions, thereby producing incorrect or unreliable simulation results.
To solve this problem, some Fast-SPICE vendors implemented separate SPICE engines – the slower, more accurate one for the analog and the faster, less accurate one for the digital and memory. At best this is a patchwork solution that may require manual intervention and frequent tuning while still producing inaccurate results. Additionally, the analog SPICE engine may run so slow on its portion of the design that the entire simulation is bottlenecked.
Other SPICE vendors, targeting analog designs, created a special version of Fast-SPICE to target analog designs. They essentially rewrote Berkeley SPICE from the ground up, optimizing it to increase performance wherever possible. Their intention was to simulate entire mixed-signal designs with Berkeley SPICE accuracy. Even with their optimizations, simulating at this level of accuracy required solving an extremely large system of nonlinear equations. The resulting matrices were huge and the number of BSIM evaluations was staggering. At best this type of approach can yield only a 5-10X performance improvement, which is grossly insufficient for many of today’s larger mixed-signal netlists that may contain multiple gigabytes of parasitics. For such designs, runtimes of weeks and months would not be uncommon.
Performance
Nascentric’s patented technology enables OmegaSim AMS to perform 10X faster than other Fast-SPICE simulators and 1000X faster than traditional SPICE simulators. With multi-threading and multi-processing the speed advantage can be even greater.
OmegaSim AMS has the combination of performance and accuracy required for today's large mixed-signal blocks with millions of devices and parasitics.
Capacity
OmegaSim AMS handles the largest mixed-signal blocks of any commercial SPICE or Fast-SPICE tool on the market. It was specifically designed to handle the challenges of sub-65 nanometer designs. It has a particular advantage in handling large, flat, post-place and route blocks with millions of devices and millions of backannotated parasitics.
Accuracy
OmegaSim AMS obtains results within 1% accuracy of traditional SPICE for the sensitive analog circuits within mixed-signal designs. It achieves this accuracy through a patented, current-based approach and meticulous modeling of transistors. OmegaSim AMS analyzes the topology of the circuit to precisely determine silicon behavior, and then applies the appropriate algorithm to digital and analog circuits to achieve the optimal combination of accuracy and performance.
Multi-threading and Multi-processing
OmegaSim AMS was designed from the start to have multi-threading and multi-processing capabilities. For many circuits the speed-up is nearly linear with respect to the number of cores. Other commercial SPICE and Fast-SPICE tools would have to be completely rewritten to achieve this.
Multi-Engine Architecture
OmegaSim AMS uses a unique, patented, army-of-ants approach to divide and conquer complex, mixed-signal designs, thereby maximizing performance and accuracy. It decomposes the circuit into transistors, logic cells, cell blocks, interconnect structures and multiple other design entities that share a unique simulation profile.
More Information
Click here for more information or to request some literature.
|
