Mainstream PCB Design Software: Altium Designer, Cadence Allegro, and PADS

Opening Note: The Industry Logic Behind Software Choices

PCB design software usually centers on two core modules: schematic capture and PCB layout/routing. The mainstream tools engineers rely on today did not appear by accident. Altium, Cadence, and Mentor Graphics (now under Siemens) each went through a long history of mergers, acquisitions, and continuous product evolution.

From early specialization in narrow segments to market consolidation through competition and integration, the ecosystem eventually converged on three widely used platforms: Altium Designer (originating from Protel), Cadence Allegro, and PADS (originally from Mentor Graphics). These tools differ in positioning and emphasis, but the design philosophy behind them is closely related. Once you master one of them, learning the others becomes much easier.

Software is only the tool; design thinking is the real core. Before diving into each platform, one point deserves special emphasis: no matter which software you use, stackup structure and impedance control are the foundation of high-speed PCB design. If you are planning a stackup scheme, you can use the NextPCB impedance calculator for an initial check, then refine your routing rules based on simulation results for a more efficient workflow.

1. Table of Contents
2. Opening Note: The Industry Logic Behind Software Choices
3. 1. Altium Designer
4. 1.1 From Protel to Altium Designer
5. 1.2 Main Functional Modules
6. 1.3 Key Features
7. 1.4 Evolution Over Time
8. 2. Cadence Allegro
9. 2.1 Background of Cadence
10. 2.2 How Allegro Is Positioned
11. 2.3 Feature Updates in Allegro 17.4
12. 3. PADS
13. 3.1 Product Positioning and Development History
14. 3.2 Functional Analysis of PADS VX.2.2
15. 4. How to Choose the Right Software for Your Needs

1. Altium Designer

https://www.altium.com/altium-designer

The initial welcome screen for the Altium Designer installation wizard.

1.1 From Protel to Altium Designer

Altium Designer fully inherits the features and strengths of earlier versions such as Protel 99 SE and Protel DXP, while introducing substantial improvements and high-end design capabilities. It breaks away from the traditional board-level design interface by integrating FPGA design and SOPC implementation into one platform, allowing engineers to carry system design, PCB design, and embedded development forward in the same environment. The trade-off is clear: Altium Designer also places higher demands on computer hardware.

Among engineers, Altium Designer is widely known for being easy to learn and user-friendly, making it especially suitable for small and mid-sized teams as well as individual developers. However, in complex high-speed multilayer board designs, the software can consume significant system resources, and earlier versions were sometimes criticized for sluggish routing performance. That issue has been gradually improved in later releases.

1.2 Main Functional Modules

1.3 Key Features

1.4 Evolution Over Time

The development history of Altium Designer, to some extent, reflects the broader shift in PCB design tools from “good enough” to “all-in-one.” From a functional perspective, Altium Designer has continued moving toward high-speed design, high density, mixed hardware-software integration, team collaboration, and ECAD/MCAD cooperation. Its boundaries have expanded from single-board to multi-board, from low-frequency to high-speed, and from FPGA logic to 3D PCB workflows.

Overall, the sophistication of Altium Designer’s feature set comes with steadily increasing resource consumption, which has long been one of the key trade-offs faced by its development team between feature expansion and performance optimization.

2. Cadence Allegro 

https://www.cadence.com/en_US/home/tools/pcb-design-and-analysis/allegro-x-design-platform.html#allegro-x-pcb-designer

A centralized installation menu for various Cadence design suite components and utilities.

2.1 Background of Cadence

Cadence Design Systems is a major EDA company listed on NASDAQ in the United States under the ticker CDNC. It was formed in 1988 through the merger of SDA Systems and ECAD, and is one of the world’s largest providers of electronic design automation solutions.

Cadence’s solutions cover the full electronic design flow: system-level design, functional verification, IC synthesis and place-and-route, analog/mixed-signal and RF IC design, full-custom IC design, IC physical verification, PCB design, and hardware simulation modeling. Among these, its IC design, simulation, and verification tools are industry-leading. Its PCB design tool, Allegro, is positioned for high-end design scenarios and is highly regarded in the complex multilayer board segment.

Cadence entered mainland China in 1992 and subsequently established branches and R&D centers in Beijing, Shanghai, and Shenzhen. In 2008, it moved its Asia-Pacific headquarters to Shanghai. Cadence’s Beijing R&D center handles EDA software development tasks for the U.S. headquarters, while the China team also provides full-flow technical support, ranging from system simulation and verification to digital front-end/back-end, mixed RF front-end, SiP packaging, and PCB design.

2.2 How Allegro Is Positioned

By integrating schematic design, circuit simulation, PCB editing, topology-driven automatic routing, signal integrity analysis, and design output into one flow, Allegro builds a complete design chain for complex, large-scale circuit boards. Among the three mainstream software platforms, Allegro has a relatively steep learning curve, but its rigorous constraint system and powerful signal integrity analysis capabilities give it a unique advantage in high-end PCB design.

It is widely used in industries with demanding signal quality requirements such as communications, servers, and high-speed networking.

In high-speed PCB design, stackup structure and impedance control are often among the most critical factors determining success or failure. Allegro supports detailed stackup parameter settings, and it works best when paired with impedance calculation tools. If you are planning a stackup, you can use the NextPCB impedance calculator to quickly verify impedance results under different stackup configurations and use those results as a reference for constraint definition.

2.3 Feature Updates in Allegro 17.4

Allegro 17.4 is one of the more representative recent versions, with systematic improvements in user experience and performance. The main updates include the following.

3. PADS

[https://www.siemens.com/en-us/products/pcb/pads/]

The opening license prompt for a PADS installation via the Mentor Graphics installer.

3.1 Product Positioning and Development History

PADS (Personal Automated Design System) is centered on PCB tools. It was originally launched by PADS Software Inc., later acquired by Innoveda, and eventually became part of Mentor Graphics, where it served as the company’s main product line for the mid-range PCB design market. Mentor Graphics has since been acquired by Siemens, and the PADS product line continues to operate.

As a top-tier global EDA vendor, Mentor Graphics’ PADS series has long followed a product philosophy of powerful functionality and simple operation, building a broad user base in electronic engineering design. It is one of the tools frequently used by circuit design engineers and technical staff, especially in China.

3.2 Functional Analysis of PADS VX.2.2

The core positioning of PADS VX.2.2 is high-speed circuit design, with strong focus on high-speed routing constraints in both automatic and batch-processing modes. Its physical design environment is intended to serve as a clearly defined solution for high-speed circuit design.

PADS Logic serves as the schematic entry point for the PADS family. It is feature-complete and intuitive, providing efficient design data input for PADS Layout. PADS Layout/Router, meanwhile, is the core environment for complex high-speed PCB design. Built on a shape-based, rule-driven placement and routing approach, and combining automatic and interactive routing methods, it integrates the front-end and back-end tool chain, including test preparation and manufacturing. PADS Layout also supports Microsoft-standard programming interfaces and can integrate with other Windows toolsets through Visual Basic programs and OLE automation, making customized workflow development convenient.

4. How to Choose the Right Software for Your Needs

No matter which tool you use, the stackup design of a high-speed multilayer board is foundational work that cannot be ignored. Stackup parameters determine differential impedance, characteristic impedance, and coupling effects, all of which directly affect routing rule definition. When planning a stackup, you can use the NextPCB impedance calculator in HQDFM to verify different stackup configurations and use the results as the basis for later constraint settings.

The design philosophies of these three software platforms are closely aligned. Once you master one, the cost of learning the others drops significantly. Software is the vehicle; design thinking is the real competitive advantage.

Frequently Asked Questions about PCB Design Software

Q: Which software is best for beginners or individual developers? A: Altium Designer is generally considered the most beginner-friendly. Its unified interface and intuitive design flow make it easier to learn compared to the more rigid constraint systems of Allegro or the multi-tool environment of PADS.

Q: Can I open files created in one software with another? A: While each platform uses proprietary file formats, most offer import wizards. For example, Altium and Allegro both have tools to import PADS files, and PADS VX.2.2 has improved its ability to import Altium projects. However, some manual adjustment of constraints and rules is almost always required after conversion.

Q: Why is Cadence Allegro preferred for server and communication board design? A: High-end designs like servers involve extremely complex high-speed signals and dense multilayer stackups. Allegro’s strength lies in its sophisticated constraint manager and integrated signal integrity tools, which ensure that strict timing and impedance requirements are met across thousands of connections.

Q: Is there a significant difference in hardware requirements between these tools? A: Yes. Altium Designer, due to its "all-in-one" integration and native 3D engine, tends to be more resource-intensive and requires a more powerful GPU and more RAM for smooth performance. PADS is relatively lightweight, while Allegro’s performance depends heavily on the complexity of the design and the simulation modules being used.

Q: Does master of one software help in learning the others? A: Absolutely. While the keyboard shortcuts and menu layouts differ, the core logic—schematic capture, footprint creation, layer stackup management, and design rule checking—is fundamentally the same. The transition usually involves learning the specific interface and command syntax of the new tool rather than relearning PCB design principles.

Q: How important is external impedance calculation when the software has built-in tools? A: Built-in tools are excellent for real-time routing, but external calculators (like the NextPCB impedance calculator) provide a vital cross-check. They are often faster for initial "what-if" scenarios when planning your stackup before you have even started the layout, ensuring your physical design starts on a technically sound foundation.