ASCO 0.4.6

ASCO aka A SPICE Circuit Optimizer project aims to bring circuit optimization capabilities to existing SPICE simulators.
Main features:
ASCO is the result of an academic research which in itself did not intended to create a new tool, but only to design high performance analog low-power low-voltage circuits for mobile communications. Interaction with other experienced designers has resulted in the ideas existing in the ASCO tool. With the exception of the DE optimizer all code has been personally written. The key features of the ASCO tool are:
- Simulator independent: currently out-of-the-box support for Eldo (TM), HSPICE (R), LTSpice (TM) and Spectre (R) exist. More are to be included in future releases.
- Number of variables: there is, in theory, no limit to the number of circuit variables that can be optimized, except those constraints imposed by the available computer memory and/or the time required to generate a functional circuit. It is currently hardcoded in the C code.
- PVT corners: by using the simulator functionality, the possibility to test various design corners and Monte Carlo analysis is only limited to the simulator capability and by the time it takes to finish the optimization.
- Efficiency: the optimization algorithm features a global optimization using differential evolution. It has been used on a variety of applications and is know to produce good results in an acceptable time.
- Within the supported SPICE simulators, arbitrary netlist can be optimized on different conditions without having to recompile the code.
- File format: all outputted data and log information is stored in plain text format. This guarantees that they will be always readable in the future. In addition, it makes possible to use other existing tools to post-process the optimization results.
- Its free software: the code is available under the GNU GPL license.
ASCO has been designed to address problems that are particular of electric circuits. Although not limited, some possible applications can include:
- Fully redesign a new circuit described in a SPICE netlist.
- Reuse, optimize an existing circuit.
- Migrated an existing and working design to a more advanced semiconductor technology process effortlessly.
- Increase the robustness and yield of an already designed circuit by guaranteeing that it comply with all design goals and constraints in some/all process corners at will.
- Easily explore a new operating point (design space) for an already existing topology, to reduce power consumption, area or both.
- Look for a feasible new design topology before investing a considerable time trying to derive equations that describe its operation.
- Refer to Chapter 5 for ready to use practical examples to introduce you to ASCO, a SPICE circuit optimization tool. Bellow is a list of the examples that can be found with the objective of introducing the tool, its usage and applications.
- Optimization from scratch a digital inverter circuit to achieve minimum power consumption while fulfilling the design constraints; guarantee that this is valid for different process corners and also take into account device parameter mismatch (Monte Carlo).
- Optimization of a three stage operation amplifier featuring the frequency compensation technique described in [Ram05]. A total of 21 variables and five constraints/performance goals are used with the objective of obtaining the most power efficient circuit.
- The simple class-E amplifier intended for operation in the GSM-850 band is given. A more realistic model representing a differential two stage power amplifier, including all relevant circuit and board parasitics to better describe the circuit measurement performance alongside with measurements from a manufactured chip in a 0.35 um CMOS commercial technology, is given in [Ram05].
Enhancements:
- Improvements were made in the RF module functionality.
- Support was included for logarithmic search space for the existing variables.
- Code refinements and bugfixes were made.