Synthesis of high-performance analog circuits in ASTRX/OBLX

Abstract

Abstract-We present a new synthesis strategy that can automate fully the path from an analog circuit topology and performance specifications to a sized circuit schematic. This strategy relies on asymptotic waveform evaluation to predict circuit performance and simulated annealing to solve a novel unconstrained optimization formulation of the circuit synthesis problem. We have implemented this strategy in a pair of tools called ASTRX and OBLX. To show the generality of our new approach, we have used this system to resynthesize essentially all the analog synthesis benchmarks published in the past decade; ASTWOBLX has resynthesized circuits in an afternoon that, for some prior approaches, had required months. To show the viability of the approach on difficult circuits, we have resynthesized a recently published (and patented), high-performance operational amplifier; ASTWOBLX achieved performance comparable to the expert manual design. And finally, to test the limits of the approach on industrial-sized problems, we have synthesized the component cells of a pipelined A/D converter; ASTWOBLX successfully generated cells 2-3 x more complex than those published previously.

Design of Analog Integrated Circuits using Simulated Annealing/Quenching with Crossovers and Particle Swarm Optimization

“…This approach allows some level of independence of the optimization regarding the initial and final temperature values. The use of a technique called AWE (Asymptotic Waveform Evaluation) was proposed in the tool ASTRX [19] together with the use of SA. AWE could replace the SPICE simulations as it predicted the small signal behavior of the circuit using a reduced complexity model.…”

A Comparison of Semi-deterministic and Stochastic Search Techniques

“…In this implementation the modified Lam-Delosme schedule is used [9] with rules selected based on quality metrics [10] and dynamic constraint weights [11].…”

An algorithm for exploiting modeling error statistics to enable robust analog optimization

“…In local search methods performance is tied to the initial points of the algorithm. Global search methods require a potentially much larger number of SPICE evaluations for the global exploration to converge [12], and typically have exponential complexity.…”

“…The existing work has fallen into two major categories based on how they evaluate a solution point to drive optimization: approaches relying on extensive use of SPICE simulations [11], [12], [9], and those that construct an analytical model of circuit behavior and use the model to drive the optimization [5], [10], [13], [6]. Clearly, evaluating a solution point via a SPICE simulation gives the most accurate measure of the feasibility and optimality of a solution.…”