FREMONT, Calif. A mixed-signal IC simulator introduced Monday (March 29) by Avant! Corp. promises that performance simulations of million-transistor circuits will run 10 to 1,000 times faster than Spice. Star-MS is a dual-engine simulator built on two existing Avant! simulators the Star-Sim analog simulator initially developed by Anagram Inc., and the Polaris Verilog digital simulator. Avant! merged with Anagram in 1996.
Star-MS can be used to evaluate the performance of large ICs with both analog and digital subsystems. Typically, a transistor-level simulator is used for verification, but Star-MS is fast enough to be utilized in the design process for circuit optimization, according to Stacy Whiteman, product manager for circuit simulator products at Avant! (Fremont, Calif.). Star-MS could be used for full chip verification and to verify new intellectual property blocks within a larger IC, she said.
Mixed-signal ICs such as data converters or analog signal modulators/demodulators form the heart of high-volume communications circuits, disk drives and multimedia ICs. The need to simulate these ICs and push them to market faster is spurring the growth in mixed-signal simulators and design tools. After years of dormancy, this market is expected to grow 28 percent in 1999, according Rita Glover, principal analyst at EDA Today (Phoenix).
Mixed-signal IC simulators especially those using "glued" or dual-core simulation engines (one for analog; another for the digital portions of a circuit) have traditionally been plagued with a number of run-time problems. First, the speed of the system is generally a function of the Spice analog simulator. On a logic simulator using discrete time steps, a million-transistor circuit might be simulated in a half hour, but the analog behavior of same circuit might take days, or even weeks, to calculate in Spice. In addition, the glued simulator absorbs an additional computational overhead in trying to correlate the functional simulation results from digital and analog portions of the circuit.
Thus, many technologists advocate single-core simulators as the most efficient means of simulating a mixed-signal circuit, even though it can be a burdensome task for model builders to model everything in C.
Avant! calls its Star-MS a single-kernel architecture that marries Avant!'s Star-Sim analog simulator and the company's Polaris Verilog digital simulator. Star-Sim uses a table-lookup process that drastically simplifies computational requirements, while the compiled code in Polaris Verilog offers 10 to 30 times faster simulation than interpreted Verilog, according to Avant! The accuracy is still within 5 percent of Spice, but the simulation improves from 10 to 1,000 times, said Whiteman. The analog capacity of the simulator is 5 million transistors and multi-million digital gates.