Radio frequency & microwave testing

The complexities of modern RF integration

Modern radio frequency integration presents significant challenges for engineers, who must incorporate multiple wireless technologies – such as Wi-Fi, Bluetooth, UWB, and NFC – into increasingly compact devices. This high level of integration creates a dense environment where signal integrity, coexistence, and regulatory compliance are critical concerns. Addressing these challenges requires a deep, empirical understanding of how RF systems perform in real-world scenarios. In this context, RF and microwave testing evolves from a basic quality check into a core engineering discipline, providing the essential empirical data needed to bridge the gap between simulation and a market-ready product.

Through rigorous characterization and validation, RF testing enables engineers to:

• Validate prototypes by ensuring they meet critical key performance indicators (KPIs), such as transmit power, error vector magnitude (EVM), and receiver sensitivity.
• Debug complex issues by systematically identifying and resolving problems like signal degradation, interoperability challenges between different wireless technologies, and electromagnetic interference (EMI).
• Optimize designs by fine-tuning system parameters to achieve the ideal balance between performance, power consumption, and thermal management.

Why RF testing is crucial in your design process

RF testing isn't just a final quality check. It's a critical process to ensure that your devices are performing as expected and comply with relevant regulations.

Validating core performance

While a design may appear flawless in simulation, a model is ultimately just a representation and cannot capture the full complexity of real-world behavior. The actual environment introduces countless variables, such as manufacturing tolerances, unexpected board parasitics, and unpredictable antenna characteristics, all of which can impact device performance. RF testing validates the true performance of a device by measuring the critical key performance indicators (KPIs) that define both signal integrity and overall functionality. This process involves assessing transmit power to ensure sufficient range, receiver sensitivity to detect weak signals, and modulation accuracy (EVM) to guarantee the integrity of transmitted data. Performance validation isn’t just a pass/fail exercise: it’s about confirming that the core functionality of your product is robust and reliable when faced with real-world conditions.

Mitigating financial risk & reducing costs

Early and continuous RF testing is a direct investment in cost avoidance. By identifying issues such as poor signal integrity, antenna mismatch, or coexistence failures during the prototype stage, engineers can minimize the need for expensive rework later in the development process. This proactive approach helps prevent costly board re-spins and avoids significant project delays, ultimately safeguarding your budget and protecting your brand’s reputation from problems that could arise over the lifespan of the device.

Key parameters of radio frequency testing

A successful RF design relies on more than just theory – it's proven by precise, repeatable measurements. These measurements are the language of RF: a set of critical parameters that show your device's performance. The fundamental parameters we measure at Rohde & Schwarz to empower your engineering decisions and ensure your product meets its design targets are:

• S-Parameters:
  S-parameters are fundamental datasets that characterize the behavior of RF and microwave components by describing how signals propagate through a multi-port network. They provide a comprehensive view of a device’s performance, including both reflection and transmission properties, and are essential for understanding how components interact within a system.
• Power and frequency accuracy:
  Output power and frequency accuracy are the most basic yet critical attributes of a wireless signal. Power accuracy verifies that the actual output power of a transmitter or amplifier matches its specified design target, which is crucial for meeting regulatory limits and ensuring reliable communication. Frequency accuracy measures how closely a device’s operating frequency aligns with its intended value. Any inaccuracy can cause the signal to drift out of its designated channel or band, leading to interference and significant loss of signal integrity. In summary, frequency defines the channel or band, while power indicates the signal’s strength.
• Linearity:
  Linearity describes how accurately an RF system replicates its input signal at the output. For example, an amplifier should maintain a constant gain across a range of input power levels without introducing unwanted distortion. A linear device provides consistent gain throughout its operating range, meaning the output power remains directly proportional to the input power.
• Noise Figure:
  The noise figure measures the amount of noise a component, such as an amplifier, adds to a signal, indicating how much the device degrades the signal-to-noise ratio as the signal passes through. This parameter is critical because it directly impacts the system’s sensitivity and dynamic range, affecting its ability to detect weak signals.
• Error Vector Magnitude:
  Error Vector Magnitude (EVM) is a comprehensive metric for assessing the accuracy of digital modulation, commonly used in wireless systems. EVM quantifies the deviation of the actual signal from the ideal signal, providing a direct measure of modulation quality and overall signal integrity.
• Power consumption:
  Power consumption refers to the DC power required by an RF system for a specific task and setup, such as the energy used by an RF amplifier operating at a given frequency and gain state. It is important for system-level usage, as it influences battery life and the need for heat dissipation, and is often a key differentiator between different RF amplifier offerings.

Specialized RF testing methods at Rohde & Schwarz

While the fundamental parameters of RF are universal, applying them effectively requires specialized methodologies tailored to specific challenges. From characterizing a single transistor on a wafer to testing finished devices, each stage of the product lifecycle demands a unique approach and solution.

Here’s how our expertise at Rohde & Schwarz addresses the critical testing challenges you face every day: