Electronic circuit simulation
Encyclopedia
Electronic circuit simulation uses mathematical models to replicate the behavior of an actual electronic device or circuit.
Simulation software allows for modeling of circuit operation and is an invaluable analysis tool. Due to its highly accurate modeling capability, many Colleges and Universities use this type of software for the teaching of electronics technician
and electronics engineering programs. Electronics simulation software engages the user by integrating them into the learning experience. These kinds of interactions actively engage learners to analyze, synthesize, organize, and evaluate content and result in learners constructing their own knowledge.
Simulating a circuit’s behavior before actually building it can greatly improve design efficiency by making faulty designs known as such, and providing insight into the behavior of electronics circuit designs. In particular, for integrated circuits, the tooling (photomask
s) is expensive, breadboard
s are impractical, and probing the behavior of internal signals is extremely difficult. Therefore almost all IC design
relies heavily on simulation. The most well known analog simulator is SPICE
. Probably the best known digital simulators are those based on Verilog
and VHDL.
Some electronics simulators integrate a schematic editor
, a simulation engine, and on-screen waveforms (see Figure 1), and make “what-if” scenarios easy and instant. They also typically contain extensive model and device libraries. These models typically include IC specific transistor models
such as BSIM, generic components such as resistor
s, capacitor
s, inductor
s and transformer
s, user defined models (such as controlled current and voltage sources, or models in Verilog-A
or VHDL-AMS
). Printed circuit board
(PCB) design requires specific models as well, such as transmission line
s for the traces and IBIS
models for driving and receiving electronics.
electronics circuit simulators, popular simulators often include both analog and event-driven digital simulation capabilities, and are known as mixed-mode simulators . This means that 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 mixed-mode simulators provide accurate specification of propagation time and rise/fall time delays.
The event driven algorithm
provided by mixed-mode simulators 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 solution, 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; (a) with primitive digital elements that use timing models and the built-in 12 or 16 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. An example of a mixed-mode simulator is shown in Figure 2.
Exact representations are used mainly in the analysis of transmission line
and signal integrity
problems where a close inspection of an IC’s I/O characteristics is needed. Boolean logic expressions are delay-less functions that are used to provide efficient logic signal processing in an analog environment. These two modeling techniques use SPICE to solve a problem while the third method, digital primitives, use mixed mode capability. Each of these methods has its merits and target applications. In fact, many simulations (particularly those which use A/D technology) call for the combination of all three approaches. No one approach alone is sufficient.
Another type of simulation used mainly for power electronics
represent piecewise linear algorithms. These algorithms use an analog (linear) simulation until a power electronic
switch changes its state. At this time a new analog model is calculated to be used for the next simulation period. This methodology both enhances simulation speed and stability significantly.
Process variations occur in the manufacture of circuits in silicon.
Temperature variation can also be modeled to simulate the circuit's performance through temperature ranges.
Simulation software allows for modeling of circuit operation and is an invaluable analysis tool. Due to its highly accurate modeling capability, many Colleges and Universities use this type of software for the teaching of electronics technician
Electronics technician
Electronics Technicians help design, develop, test, manufacture, and install electrical and electronic equipment such as communication equipment, medical monitoring devices, navigational equipment, and computers. They may be employed in product evaluation and testing, using measuring and...
and electronics engineering programs. Electronics simulation software engages the user by integrating them into the learning experience. These kinds of interactions actively engage learners to analyze, synthesize, organize, and evaluate content and result in learners constructing their own knowledge.
Simulating a circuit’s behavior before actually building it can greatly improve design efficiency by making faulty designs known as such, and providing insight into the behavior of electronics circuit designs. In particular, for integrated circuits, the tooling (photomask
Photomask
A photomask is an opaque plate with holes or transparencies that allow light to shine through in a defined pattern. They are commonly used in photolithography.-Overview:...
s) is expensive, breadboard
Breadboard
A breadboard is a construction base for prototyping of electronics. The term is commonly used to refer to solderless breadboard ....
s are impractical, and probing the behavior of internal signals is extremely difficult. Therefore almost all IC design
Integrated circuit design
Integrated circuit design, or IC design, is a subset of electrical engineering and computer engineering, encompassing the particular logic and circuit design techniques required to design integrated circuits, or ICs...
relies heavily on simulation. The most well known analog simulator is SPICE
SPICE
SPICE is a general-purpose, open source analog electronic circuit simulator.It is a powerful program that is used in integrated circuit and board-level design to check the integrity of circuit designs and to predict circuit behavior.- Introduction :Unlike board-level designs composed of discrete...
. Probably the best known digital simulators are those based on Verilog
Verilog
In the semiconductor and electronic design industry, Verilog is a hardware description language used to model electronic systems. Verilog HDL, not to be confused with VHDL , is most commonly used in the design, verification, and implementation of digital logic chips at the register-transfer level...
and VHDL.
Some electronics simulators integrate a schematic editor
Schematic editor
A Schematic editor is a tool for schematic capture of electrical circuits or electronic circuits.Schematic editors replaced manual drawing of schematic diagrams, but they still retain the capability of outputting schematics on specially formatted sheets...
, a simulation engine, and on-screen waveforms (see Figure 1), and make “what-if” scenarios easy and instant. They also typically contain extensive model and device libraries. These models typically include IC specific transistor models
Transistor models
Transistors are simple devices with complicated behavior. In order to ensure the reliable operation of circuits employing transistors, it is necessary to scientifically model the physical phenomena observed in their operation using transistor models. There exists a variety of different models that...
such as BSIM, generic components such as resistor
Resistor
A linear resistor is a linear, passive two-terminal electrical component that implements electrical resistance as a circuit element.The current through a resistor is in direct proportion to the voltage across the resistor's terminals. Thus, the ratio of the voltage applied across a resistor's...
s, capacitor
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
s, inductor
Inductor
An inductor is a passive two-terminal electrical component used to store energy in a magnetic field. An inductor's ability to store magnetic energy is measured by its inductance, in units of henries...
s and transformer
Transformer
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...
s, user defined models (such as controlled current and voltage sources, or models in Verilog-A
Verilog-A
Verilog-A is an industry standard modeling language for analog circuits. It is the continuous-time subset of Verilog-AMS.Verilog-A was created out of a need to standardize the Spectre behavioral language in face of competition from VHDL , which was absorbing analog capability from other languages...
or VHDL-AMS
VHDL-AMS
VHDL-AMS is a derivative of the hardware description language VHDL . It includes analog and mixed-signal extensions in order to define the behavior of analog and mixed-signal systems ....
). Printed circuit board
Printed circuit board
A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...
(PCB) design requires specific models as well, such as transmission line
Transmission line
In communications and electronic engineering, a transmission line is a specialized cable designed to carry alternating current of radio frequency, that is, currents with a frequency high enough that its wave nature must be taken into account...
s for the traces and IBIS
IBIS Interconnect Modeling Specification
The IBIS Interconnect Modeling Specification is a behavioral, ASCII-based file format for distributing passive interconnect modeling information. The format and style of ICM are highly similar to the Input Output Buffer Information Specification , and both specifications are managed by the same...
models for driving and receiving electronics.
Types
While there are strictly analogAnalog signal
An analog or analogue signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are...
electronics circuit simulators, popular simulators often include both analog and event-driven digital simulation capabilities, and are known as mixed-mode simulators . This means that 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 mixed-mode simulators provide accurate specification of propagation time and rise/fall time delays.
The event driven algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
provided by mixed-mode simulators 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 solution, 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; (a) with primitive digital elements that use timing models and the built-in 12 or 16 state digital logic simulator, (b) with subcircuit models that use the actual transistor topology of the integrated circuit
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
, and finally, (c) with In-line Boolean logic
Boolean logic
Boolean algebra is a logical calculus of truth values, developed by George Boole in the 1840s. It resembles the algebra of real numbers, but with the numeric operations of multiplication xy, addition x + y, and negation −x replaced by the respective logical operations of...
expressions. An example of a mixed-mode simulator is shown in Figure 2.
Transmission line
In communications and electronic engineering, a transmission line is a specialized cable designed to carry alternating current of radio frequency, that is, currents with a frequency high enough that its wave nature must be taken into account...
and signal integrity
Signal integrity
Signal integrity or SI is a set of measures of the quality of an electrical signal. In digital electronics, a stream of binary values is represented by a voltage waveform. However, digital signals are fundamentally analog in nature, and all signals are subject to effects such as noise,...
problems where a close inspection of an IC’s I/O characteristics is needed. Boolean logic expressions are delay-less functions that are used to provide efficient logic signal processing in an analog environment. These two modeling techniques use SPICE to solve a problem while the third method, digital primitives, use mixed mode capability. Each of these methods has its merits and target applications. In fact, many simulations (particularly those which use A/D technology) call for the combination of all three approaches. No one approach alone is sufficient.
Another type of simulation used mainly for power electronics
Power electronics
Power electronics is the application of solid-state electronics for the control and conversion of electric power.-Introduction:Power electronic converters can be found wherever there is a need to modify a form of electrical energy...
represent piecewise linear algorithms. These algorithms use an analog (linear) simulation until a power electronic
Power electronics
Power electronics is the application of solid-state electronics for the control and conversion of electric power.-Introduction:Power electronic converters can be found wherever there is a need to modify a form of electrical energy...
switch changes its state. At this time a new analog model is calculated to be used for the next simulation period. This methodology both enhances simulation speed and stability significantly.
Complexities
Often circuit simulators do not take into account the process variations that occur when the design is fabricated into silicon. These variations can be small, but taken together can change the output of a chip significantly.Process variations occur in the manufacture of circuits in silicon.
Temperature variation can also be modeled to simulate the circuit's performance through temperature ranges.
See also
- List of free electronics circuit simulators
- Qucs
- SPICESPICESPICE is a general-purpose, open source analog electronic circuit simulator.It is a powerful program that is used in integrated circuit and board-level design to check the integrity of circuit designs and to predict circuit behavior.- Introduction :Unlike board-level designs composed of discrete...
- Transistor modelsTransistor modelsTransistors are simple devices with complicated behavior. In order to ensure the reliable operation of circuits employing transistors, it is necessary to scientifically model the physical phenomena observed in their operation using transistor models. There exists a variety of different models that...
- VerilogVerilogIn the semiconductor and electronic design industry, Verilog is a hardware description language used to model electronic systems. Verilog HDL, not to be confused with VHDL , is most commonly used in the design, verification, and implementation of digital logic chips at the register-transfer level...
- VHDL
- YenkaYenkaYenka is a suite of educational software products which lets students simulate scientific experiments, create mathematical models, design electronic circuits or learn computer programming. Yenka is developed by Crocodile Clips Ltd.- Features :...
- PLECSPLECSPLECS is a Simulink toolbox for system-level simulations of electrical circuits developed by Plexim.It is especially designed for power electronics but can be used for any electrical network....
- Livewire (software)Livewire (software)Livewire is a CAD product developed by New Wave Concepts. It allows the user to create and simulate electronic circuits using an extensive gallery of circuit components. The finished circuit can be exported into sister-program PCB Wizard in order to route it for a Printed circuit board.-See...
- PSIM
External links
- Free Great Java Circuit Simulation by Paul Falstad - Free Educational Great Java Circuit Simulation
- Linear Tech's LTSpice - LTSpice analog and digital simulator, runs under Windows and Linux.
- Multisim website - Circuit simulation software from National Instruments
- CircuitLogix website - electronics circuit simulator
- Circuit Simulator Analyses - circuitdesign.info
- Electronic Circuit Simulation Applet
- GeckoCIRCUITS website - Free power electronics circuit simulator (Java Applet)
- Saber website - Multi-domain Circuit Simulation software from Synopsys