RF and Microwave Circuit Design Software

RF circuit design involves designing and simulating electronic circuits that operate in radio frequencies (RF) and millimeter-wave frequencies, typically ranging from a few kHz to several hundred GHz. Various applications use these circuits such as wireless communication, radar systems, satellite communication, automotive, and more.

Circuit simulation is a computational technique used to model and analyze the behavior of electronic circuits. The first step is creating a mathematical circuit model representing the circuit's components and interconnections. Mathematical equations or models describe each component capturing its behavior under different operating conditions. After modeling the circuit, engineers use simulation software to solve the equations and analyze the circuit's behavior. Today’s increasingly complex, dense RF circuit designs require complex simulators capable of handling large and intricate circuits.

The critical components of an RF circuit include amplifiers, oscillators, filters, mixers, modulators / demodulators, antennas, transmission lines, and matching networks.

The Smith chart represents complex impedance and reflection coefficient values in a two-dimensional chart. It's typically plotted on a polar coordinate system, with the horizontal axis representing resistance (real part) and the vertical axis representing reactance (imaginary part). The Smith chart is a powerful tool for RF design engineers, providing a graphical representation that simplifies the analysis and design of transmission lines, impedance-matching networks, and other RF circuits.

Some common challenges in RF circuit design include impedance matching, noise, linearity, stability, bandwidth, power consumption, and interference. As design densification increases, advanced design challenges could include integrating different materials, 3D integration, and advanced packaging techniques.

Using higher frequency transistors complicates the design flow for designing stable circuits. In today’s circuits, the gain is higher due to increasing transistor operating frequency limits (fTs), or the frequency at which unity current gain goes to zero. Tight integration and feedback because of the RF coupling can cause instability problems at lower frequencies due to significant increases in gain. The Keysight Winslow stability probe (WS-probe) is an in-circuit probe that replaces the traditional setups for multi-device amplifiers to derive the necessary stability measures quickly and efficiently.

Measuring error vector magnitude (EVM) can have its challenges — the first task is determining measurement speed. Distortion EVM estimates the error vector magnitude of nonlinear simulations without needing an external system simulator. Distortion EVM can help designers quickly assess the EVM during the design phase and speed up simulation time by a factor of ten. The second task requires accurately generating a representative 5G test waveform approximating the signal characteristics. If you can find an accurate representative waveform, you must demodulate or demultiplex the signals to arrive at the error vector magnitude. Using these test signals together with distortion EVM measurements shortens the test time for quick verification in circuit design.

Electromagnetic circuit co-simulation eliminates the delay and potential errors introduced by a separate electromagnetic (EM) solver by running a 3D finite element model (FEM) simulation automatically in the same environment with easy automated setup and analysis. This process frees the RF circuit designer to perform 3D electromagnetic analysis and EM/circuit co-simulation iteratively in the design phase. Electromagnetic / circuit co-simulation yields an order of magnitude faster setup, giving you time to schedule other simulation tasks.

AI / machine learning (ML) can increase productivity and organizational efficiency by tailoring your electronic design automation (EDA) solutions into efficient workflows and interconnected design processes. Automation and application programming interface based workflows are a cornerstone of digital transformation. With Python application programming interfaces (APIs) for Keysight EDA tools, you can control data, simulators, platforms, and processes to engineer more predictable outcomes.

The continuous rise in substrate layer counts, smaller form factors, complex packaging technologies, and closer design proximities are factors that contribute to the increasing complexity of designs. Keysight ADS is the industry-proven multi-technology 3D layout and integrated EM-circuit co-simulation platform for designing RF modules that contain radio frequency integrated circuits (RFICs) , packaging, antennas, and RF printed circuit boards (PCBs).