CircuitLogix

Fast, accurate simulation of electronic circuits is essential because it provides the information needed to perform accurate analysis of circuit behavior. SPICE simulators are used to verify that analog and mixed-signal circuits will yield the expected outputs. A schematic netlist file and circuit input values are fed to the SPICE software, which simulates the circuit's behavior for a specified length of time. CircuitLogix allows for the observation of voltage and current levels at any circuit node as they change with frequency and time. It allows for obtaining accurate results even when simulating complex circuits where hierarchical blocks are reused. The CircuitLogix simulation engine is based on Berkeley SPICE, and contains a GUI to make circuit design easier and more efficient.

The CircuitLogix 32-bit SPICE engine is interactive, allowing, for example, the frequency of sources to be changed, potentiometers adjusted, and switches thrown during simulation. The SPICE engine is fully integrated with the schematic capture and waveform tools; CircuitLogix passes schematic edits to the simulator automatically while running. Components such as fuses, LEDs and controlled switches are automatically updated in the schematic as the simulation runs.

CircuitLogix simulates analog, digital, and mixed analog-digital circuits. The simulator first divides the circuit into analog and digital portions. The analog circuitry is simulated with the time-step driven SPICE engine, while the digital parts are simulated separately with an event-driven simulation engine. The CircuitLogix digital engine was developed directly in .NET, faster than SPICE macros. Because the simulator automatically performs signal conversion, it is possible to connect any analog or digital part to any other. The system’s model library contains hybrid parts for analog-to-digital and digital-to-analog conversion.

CircuitLogix is a mixed-mode schematic editor, and includes both analog and event-driven simulation capabilities: any simulation may contain components that are analog, event driven (digital or sampled-data), or a combination of both. An entire mixed signal analysis can be driven from one integrated schematic. All the digital models in CircuitLogix provide accurate specification of propagation time and rise/fall time delays.

The event-driven algorithm used by CircuitLogix is general-purpose and supports non-digital types of data. For example, elements can use real or integer values to simulate DSP functions or sampled data filters. Because the event-driven algorithm is faster than the standard SPICE matrix, simulation time is greatly reduced for circuits that use event-driven models in place of analog models.

Mixed-mode simulation is handled on three levels by CircuitLogix: (a) with primitive digital elements that use timing models and a built-in 12-state digital logic simulator, (b) with subcircuit models that use the actual transistor topology of the integrated circuit, and finally, (c) with In-line Boolean logic expressions. These two modeling techniques use SPICE to solve a problem while the third method, digital primitives, uses mixed-mode capability.

The component library includes:

Digital primitives

Gates, DeMorgan symboled gates, buffers, inverters, flip-flops

Semiconductors

Semiconductor Resistors & capacitors, diodes, Schottky & Zener diodes, Bridge rectifiers, Varactor

Transistors, FETs

BJT, IGBT, UJT, PUT, MESFET, MOSFET, Darlington transistor

Displays, indicators, switches

LEDs, 7-Segment LEDs, Hex display, Hex key, Logic display, NC push-button, NO push button, SPDT PB, Piezo buzzer, Pulser, Latch coil, Polar latch, Rocket, SCOPE, Stepper, Stoplight, Window

Integrated Circuits

Digital ICs

1K RAM, 32x8 PROM, complete selection of 40xx, 41xx, 45xx, 47xx, 74xxx IC's

Linear ICs

Op amps, Comparators, Timers, Buffers, CDAs, Modulators, A/D converters & D/A converters, PLL, VCO

Relays

Control relay, SPST, DPDT, Individual contacts and coils (enable creation of any relay)

Power supplies, Sources

Battery, Voltage Terminal, Signal generator, I Source, V Source, I->I Source, V->I Source, I->Switch,V->Switch, I->V Source, V->V Source

Math devices

A wide variety of devices for manipulating quantities

Miscellaneous Devices

Crystals, Fuses, Transformers, DC Motor, F-V & V-F converters

Transmission lines

Lossless, Lossy, and Uniform Distributed RC

Vacuum tubes

12AU7, 12AX7, 5879, 6L6GC, 6SN7, 7199P, 7199T

Instruments

Oscilloscope, Digital Multimeter, Bode plotter, Curve tracer, Data Sequencer, Signal generator, Logic analyzer, Logic probe, Logic Pulser

Simulation Controls

Initial Condition and Nodeset devices

Miscellaneous

Optoisolators, Photodiodes, Voltage regulators, References, SCRs, Triacs

• Comparison of EDA Software

• Official website