Source: http://www.vlsiacademy.org/open-source-cad-tools.html

OPEN SOURCE CAD TOOLS

Tool	Description	Type	Function
Xcircuit	A general-purpose drawing program and also a specific-purpose CAD program for circuit schematic drawing and schematic capture.	Mixed signal	Schematic
Ktechlab	Is a schematic capture and simulator.it is a an IDE for microcontrollers and electronics. It supports circuit simulation, program development for microcontrollers and simulating the programmed microcontroller together with its application circuit.	Mixed signal	Schematic, simulator and microcontroller
gnucap	A general purpose circuit simulator with its engine designed to do true mixed-mode simulation.The primary component is a general purpose circuit simulator. It performs nonlinear dc and transient analyses, fourier analysis, and ac analysis. Spice compatible models for the MOSFET (level 1-7), BJT, and diode are included in this release.	Mixed signal	Circuit simulator
ngspice	A mixed level/signal circuit simulator	Mixed signal	Circuit simulator
qucs (Quite Universal Circuit Simulator)	Qucs is a circuit simulator with graphical user interface. The software aims to support all kinds of circuit simulation types, e.g. DC, AC, S-parameter and harmonic balance analysis. Pure digital simulations are also supported using VHDL and/or Verilog.	Mixed signal	Simulator + Verilog + VHDL
IRSIM	Is a switch-level simulator originally originating from Stanford	Mixed signal	Circuit simulator
Icarus Verilog	Is a Verilog simulation and synthesis tool. It operates as a compiler, compiling source code written in Verilog (IEEE-1364) into some target format. For batch simulation, the compiler can generate an intermediate form called vvp assembly. This intermediate form is executed by the "vvp'' command. For synthesis, the compiler generates netlists in the desired format.	Digital	Simulator & Synthesis
Verilator	Verilator is the fastest free Verilog HDL simulator. It compiles synthesizable Verilog, plus some PSL, SystemVerilog and Synthesis assertions into C++ or SystemC code. It is designed for large projects where fast simulation performance is of primary concern, and is especially well suited to create executable models of CPUs for embedded software design teams.	Digital	Verilog HDL simulator & synthesis
ghdl	Is a tool to generate metal layers and vias to physically connect together a netlist in a VLSI fabrication technology. It is a maze router, otherwise known as an "over-the-cell" router or "sea-of-gates" router.	Digital	VHDL simulator (doesn't do synthesis)
ChipVault	Is a chip development program for organizing VHDL and Verilog designs. ChipVault displays designs hierarchically and provides for rapid design navigation and editor launching. ChipVault provides hooks for performing bottom-up tasks such as launching RTL compilers, synthesis, block generation and instantiation, and includes simple to use Revision Control and Issue Tracking systems to help facilitate large group design projects with multiple designers and hundreds of design files.	Digital	VHDL & Verilog RTL compiler & synthesis
GTKwave	Is a waveform viewer that can view VCD files produced by most Verilog simulation tools, as well as LXT files produced by certain Verilog simulation tools.	Mixed signal	Wave viewer
Gwave	Is a waveform viewer for the output of analog electronic circuit simulators such as spice. It displays the data as 2-D plots, andallows for interactive scrolling, zooming, and measuring of thewaveforms	Analog	Wave viewer
LabPlot	Is a free software data analysis and visualization application built on the KDE Platform	Analog	Wave viewer
gEDA Suite	A full suite of Electronic Design Automation tools.	Mixed signal	Full suite (electrical circuit design, schematic capture, analog and digital simulation, prototyping, and production)
Alliance	Is a complete set of free CAD tools and portable libraries for VLSI design. It includes a VHDL compiler and simulator, logic synthesis tools, and automatic place and route tools. A complete set of portable CMOS libraries is provided, including a RAM generator, a ROM generator and a data-path compiler.	Mixed signal	Design flow from VHDL up to layout, (VHDL Compilation and Simulation, Model checking and formal proof, RTL and Logic synthesis, Data-Path compilation, Macro-cells generation, Place and route, Layout edition, Netlist extraction and verification, Design rules checking)
Electric	Electric is a sophisticated electrical CAD system that can handle many forms of circuit design, including custom IC layout (ASICs), schematic drawing, hardware description language specifications, and electro-mechanical hybrid layout	Mixed signal	From HDL to layout and some extra
Magic	Magic is a venerable VLSI layout tool. Magic VLSI remains popular with universities and small companies. Magic is widely cited as being the easiest tool to use for circuit layout, even for people who ultimately rely on commercial tools for their product design flow.	Mixed signal	Circuit Layout
Toped	Is a cross-platform IC layout editor supporting GDS, OASIS and CIF formats. It is an open source project licensed under the GNU General Public License. The project is under active development. focuses on rendering speed and quality of the screen output.		IC layout editor
Netgen	A tool for comparing netlists, in analog or mixed-signal circuits that cannot be simulated in reasonable time.	Mixed signal	LVS
Dragon	Dragon is a fast, effective standard-cell placement tool for both variable-die and fixed-die ASIC design. It was designed and implemented by NuCAD group in Dept. of ECE, Northwestern University, and ERLAB in Computer Science Dept., UCLA. Dragon does wirelength and routability optimization by combining powerful hypergraph partitioning package (hMetis) with simulated annealing technique. It is a university tool that produces high-quality placement comparable with commercial software such as ITools (formerly TimberWolf) and Cadence QPlace.	Digital	Placement
Fairly Good Router (FGR)	FGR is free open-source software for global routing, based on Lagrange Multipliers --- an approach similar to what industry routers use, but with greater mathematical rigor and robust performance. Unlike most other academic tools, FGR is self-contained and does not rely on ILP or external Steiner-tree constructors.	Digital	Router
Qrouter	Is a tool to generate metal layers and vias to physically connect together a netlist in a VLSI fabrication technology. It is a maze router, otherwise known as an "over-the-cell" router or "sea-of-gates" router.	Digital	Detail router
OS-VVM	Open Source - VHDL Verification Methodology (OS-VVM) delivers advanced verification test methodologies, including Constrained and Coverage-driven Randomization, as well as Functional Coverage, providing advanced features to VHDL design engineers while enabling them to continue to develop using VHDL.	Digital	Verification
Teal	Helps you perform verification by providing a set of capabilities that access HDL signals and enable actions based on changes in the values of these signals.	Digital	Verification
Jove	Is a set of Java APIs and tools to enable Verilog hardware design verification of ASICs and FPGAs using the Java programming language.	Digital	Verification
PCB	Is free software for designing printed circuit board layouts. It has many features and is capable of professional-quality output.	PCB	The printed circuit board layout editor
FreePCB	Is a free, open-source PCB editor for Microsoft Windows, released under the GNU General Public License. It was designed to be easy to learn and easy to use, yet capable of professional-quality work.	PCB	PCB editor
Fritzing	Integrated tool for breadboard, schematic, and PCB design. Targeted at non-engineers (designers, artists, researchers, hobbyists) and users of micro-controller platforms such as Arduino.	PCB	Breadboard, schematic, and PCB design
KiCad	KiCad provides for all design stages through the same interface: Schematic capture, PCB layout, Gerber generation/visualization, and library editing are all standard features. It also has a "3D view" feature for PCBs. It is available for all three major operating systems	PCB	PCB schematics and layout
OMNeT++	Is a discrete event simulation environment. Its primary application area is the simulation of communication networks, but because of its generic and flexible architecture, is successfully used in other areas like the simulation of complex IT systems, queueing networks or hardware architectures as well.	Electronic system level	Detail router
SystemC	Clunky class library for digital design.	Electronic system level	Clunky class library for digital design
myHDL	Is a Python package for using Python as a hardware description language.	Electronic system level	Hardware description language

ISRO and Bangalore based Navika gets India GPS freedom

India gets the technology-freedom in one of the key areas of global positioning systems (GPS), which is important not only for improving the lives of most of Indians and also for strategic purposes. 

With the launch of seventh satellite by ISRO for global positioning Systems application, India's indigenous GPS system named NAVIC is up and running fully. NAVIC is the sixth GPS satellite constellation system in the world. 

So with this Make-in-India achievement in space technology, there is also another Make-in-India achievement in electronics components, where an India owned Bangalore company called Navika Electronics is making GNSS/GPS semiconductor chipsets for receiving GPS data. This is also significant because there are hardly very few Indian companies designing and selling semiconductor chips in their own brand. Navika has offices both in Bangalore and Singapore.

AST-230 from Navika is a GPS SOC for portable electronics applications. The AST-230 SOC is powered by ARM processor core ARM7TDMI. AST-230 features 16-Channel high performance GPS-SBAS baseband supporting indoor positioning. A internal memory of 2MB SRAM, USB 2.0, CAN2.0, SPI, I2C, UART are some of the features available in this chip.

AST-400 is another similar product from Navika. AST-400 integrates GPS-SBAS RF front-end with a high performance GPS-SBAS digital baseband/processor, making it suitable for applications which require smaller footprint.

Another product AST-GPSRF from Navika also packs RF front-end chip for down conversion and amplification of GPS and Galileo signals. AST-GPSRF is designed for L1 (1575.42 MHz), C/A GPS band receivers and OS Galileo band receivers.

There are lot more GPS/GNSS product solutions from Navika for different GPS/GNSS applications.

Check out the website http://www.navika-electronics.com for more details on this fabless Indian semiconductor company. 

AEE Boosts Efficiency for Lower-Output-Voltage Step-Down Converters

Source: http://electronicdesign.com/power/aee-boosts-efficiency-lower-output-voltage-step-down-converters

A common challenge faced by every power-supply designer is the ability to achieve high-efficiency targets with lower-output-voltage step-down converters. For example, a 3.3-V output-voltage power supply may provide 91% efficiency at its full load, whereas a 1.8-V version may provide only 84% at full load. This decrease in efficiency produces higher operating temperatures than otherwise would be possible. And for portable systems, it wastes too much battery power. The hotter operating temperatures or shorter battery run times are clearly not desired by those using tablets, servers, or solid-state drives (SSDs) that contain these power supplies.

A new power-conversion approach is needed to keep efficiency high, regardless of the output voltage. One such method, automatic efficiency enhancement (AEE), provides higher efficiency with lower output voltages in these types of systems.

Why Does Efficiency Drop?

The efficiency drop for lower output voltages relates directly to the decreased amount of output power without a corresponding decrease in power loss. In a step-down converter, the losses are grouped into switching losses and conduction losses. Switching losses mostly depend on the input voltage, output current, and switching frequency. Conduction losses mostly depend on the output current and MOSFET resistances. Since the output voltage isn’t a strong contributor to the amount of loss, the losses don’t decrease as much as the output power.

Lower output voltages mean less output power, which is output current multiplied by the output voltage. Since efficiency is defined as output power divided by the output power plus the losses, lower efficiency results from the lower output power—but with the same losses.

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As an example, a 3.3-V output-voltage power supply delivering 6 A of output current with 2 W of loss produces 91% efficiency. The same power supply configured for a 1.8-V output voltage generates about the same 2 W of loss. This results in 84% efficiency due to the reduced output power. When configured for a 0.9-V output voltage, this 2 W of loss yields just 73% efficiency. Because the switching frequency, MOSFET resistances, output current, and input voltage are held constant in this comparison, losses are roughly the same, with 7% and 18% lower-efficiency results, respectively.

Two Higher-Efficiency Solutions

Input voltage and output current are defined by the system and load; thus, they’re not easily changeable. Power-supply designers need to either lower the switching frequency or adjust the MOSFET resistances to obtain higher efficiency for lower output voltages.

Usually, it’s impossible for power-supply designers to adjust the resistance values, because both high- and low-side MOSFETs are integrated inside most modern step-down converters. While it may be possible to have multiple step-down converter integrated circuits (ICs) available for use—each optimized for a specific output voltage—this isn’t generally practical from an IC design perspective. As a result, it’s typically not present in the market. It also creates more ICs in the bill of materials (BOM), which complicates the system design.

Lowering the switching frequency reduces the switching losses and increases efficiency. In many integrated step-down converters, it’s possible to adjust the frequency. However, adjusting the switching frequency usually necessitates a recalculation of the output filter and loop-compensation circuitry. This requires more design effort and time, and probably different components for different output-voltage circuits in the system. And that, once again, increases BOM count.

Intelligently Adjust Switching Frequency with AEE

Without any designer intervention, AEE adjusts the switching frequency to increase efficiency while using the same output filter and loop compensation. The switching frequency is automatically adjusted, based on the input voltage and output voltage, to maximize efficiency while maintaining control-loop stability and output-filter effectiveness. The frequency needn’t be set at a specific operating point optimized only for certain operating conditions; it dynamically adjusts itself during operation. Figure 1 shows the switching frequency for 3.3-, 1.8-, and 0.9-V output-voltage circuits running at 6 A of load current across a 6- to 15-V input-voltage range.

1. A two-phase step-down converter, such as the TPS62180, uses AEE to adjust the switching frequency based on input voltage and output voltage.

For lower output voltages, the switching frequency is reduced to maintain an appropriate amount of ripple current in the inductor. In the more common peak-current-limit type of step-down converter IC, the peak inductor current defines the IC’s available output current.

With the fixed level of the current limit set inside the IC, the peak inductor current must remain below the current-limit level at the full output current. Since the peak inductor current is the output current plus half of the inductor ripple current, the ripple current must be maintained at a low enough level. Otherwise, current limit is reached too soon and the IC is unable to provide the necessary output current.

With lower output voltages, the inductor ripple current is already reduced through Equation 1:

ΔI_L = V_OUT × (1 – V_OUT/V_IN)/(L × F_SW)                                  (1)

Because of this reduction, the switching frequency is also reduced with lower output voltages, increasing the ripple current back toward its allowed level. Figure 2 depicts the inductor ripple current calculated from the frequency data in Figure 1 and Equation 1.

2. AEE provides a constant ripple current at a given input voltage for any output voltage.

At a given operating point, the ripple current is essentially the same, regardless of the output voltage. AEE achieves this by reducing the switching frequency at the lower output voltages. Such a reduction narrows the gap in efficiency that occurs with decreasing output voltage. Figure 3 shows the efficiency when implementing AEE.

3. A two-phase step-down converter narrows the efficiency gap at lower output voltages through AEE.

Because the lower frequency at lower output voltages reduces switching losses, it also reduces total loss. This increases efficiency as opposed to most power-conversion topologies, which maintain a constant frequency for all output voltages.

Download this article in .PDF format This file type includes high resolution graphics and schematics when applicable.

Conclusion

In step-down converters such as the TPS62180, AEE provides higher efficiency than fixed-frequency, step-down converter topologies for lower output voltages. With AEE, 91% efficiency for a 3.3-V output voltage is maintained at a high level for lower output voltages: 87.5% for a 1.8-V output voltage and 82% for a 0.9-V output voltage. Such efficiencies represent a 3.5% and 9% increase, respectively, compared to fixed-frequency topologies. These efficiency increases are greatly valued in portable devices such as tablets, as well as thermally sensitive devices like SSDs and servers.