EVM characterization and PA linearization

EVM characterization and PA linearization

Power amplifier verification

In the fast-paced world of wireless connectivity, the demand for higher data rates continues to surge. Complex modulation schemes play a crucial role in meeting this demand. A low error vector magnitude (EVM) at both the component and system levels is key to ensuring that these modulation schemes are robust and stable.

Different use cases call for different modulation schemes. They are tailored to handle a wide range of transmission channels, spanning short to long distances and addressing a wide range of application demands - from high data rates in Wi Fi to lower rates for IoT scenarios. Complex modulations that use high order schemes require extremely low EVM figures to reliably decode transmitted signals.

The radio frequency (RF) frontend - with its active devices - is particularly critical to the EVM capabilities of a complete system. The main nonlinearities that cause EVM degradation come from the RF power amplifier (PA). At the system level, digital pre-distortion (DPD) is used as main linearization method to improve the overall EVM performance.

Rohde & Schwarz stands at the forefront of RF component characterization, offering industry-leading solutions for EVM validation. Numerous EVM reference test platforms around the globe rely on Rohde & Schwarz technology, cementing our position as a trusted partner in ensuring the optimal performance of wireless systems.

Master your EVM measurements

Regardless of product development stage, the focus is always on ensuring compliance with stringent EVM requirements. The primary objectives are:

  • Meeting design specifications
  • Providing EVM performance margins to account for production fluctuation
  • Validating low EVM with target application test signal, according to relevant standards
  • Monitoring additional KPIs, such as adjacent channel leakage ratio (ACLR)

During design optimization and linearization, the focus is on:

  • Enhancing the topology and technology of the RF frontend
  • Striking the right balance between efficiency, output power and gain while meeting the required EVM specifications
  • Utilizing digital pre-distortion (DPD) for signal performance improvement

In the characterization and production stages, it is important to ensure:

  • Robust validation of EVM performance
  • High measurement throughput across output power levels, frequency ranges and various operating conditions
  • Accuracy vs. cost balance

Discover the best solutions for EVM validation

When it comes to ensuring unparalleled EVM performance and versatility, Rohde & Schwarz solutions stand at the forefront of innovation.

Related products

R&S®SMW200A vector signal generator

Plus d'information

FSW signal and spectrum analyzer

Plus d'information

PVT360A Performance vector tester

Plus d'information

Benefits of our EVM characterization solutions

Rohde & Schwarz offers leading solutions for RF component characterization. Our solutions support a diverse range of digital systems - from mobile wireless and Wi Fi to wideband custom satellite link systems. Other benefits include:

  • Expansive frequency coverage - up to THz range
  • Integrated optimization with digital predistortion
  • Comprehensive instrument portfolio with options for all requirements and budgets

Related contents for EVM characterization

Webinar: A summary of testing RF power amplifier designs

Learn about testing RF power amplifiers in R&D, characterization and production stages

More information

Video: Easy and optimized EVM measurement of 5G NR signals

See how the R&S®SMW200A can be used to configure 5G NR signals for EVM measurements

Watch Video

Video: R&S®FSW-K18 supports amplifier characterization with CW and modulated stimulus

Watch a demo on amplifier characterization using the R&S®FSW, R&S®FSW-K18 and R&S®SMW200A

Watch Video

Application card: Do you know your EVM?

Understand the reference power for EVM measurements

More information

Application card: Verification of wideband power amplifiers

Discover the Rohde & Schwarz approach for verifying wideband power amplifiers

More information

Article: Optimize your signal and spectrum analyzer to address the most stringent EVM requirements

Learn how I/Q noise cancellation can help improve EVM performance

More information

Application note: Digital predistortion for improved EVM performance

Read a comprehensive guide on a test configuration that improves EVM at high output powers

More information

Knowledge+

Experience the uniquely personalized, high-quality content from the whole Rohde & Schwarz ecosystem - all in a single place. Discover now our knowledge tailored for your needs.

Video center

Get access to interesting videos and webinars about solutions, applications and products.

More information

Download Center

Search the Rohde & Schwarz download center for brochures, datasheets, technical papers, manuals, firmware, software, drivers, and more.

More information

The Rohde & Schwarz Technology Academy

You’re in great hands
Practical knowledge. Industry insight. Real experts. Only with the Rohde & Schwarz Technology Academy.

More information

Keyword + FAQs

What is EVM?

EVM stands for error vector magnitude. It is a measure of distortion for a modulated signal. EVM is based on the offset of each sample as represented in the constellation diagram, using the relation of the actual point versus the ideal point.

What is linearization?

Linearization is a method to minimize the distortion as created by non-linear components such as power amplifiers. Digital predistortion s a common example to achieve linearization.

EVM explained

EVM describes the difference of a measured sample point versus the reference point in a constellation diagram. This difference is called the error vector.

Digital predistortion of power amplifiers for wireless applications

Digital predistortion is a common method for linearization. It pre-compensates the non-linear behavior of a power amplifier and enables improved signal quality and lower bit error rates in wireless applications.

How to measure EVM?

EVM is most commonly measured by using a spectrum or signal analyzer connected to the output of the device under test.

How to calculate error vector magnitude?

EVM is calculated by comparing the length of the red error vector either to the length of the green vector (in the case of a peak or maximum power normalization) or to the length of blue vector (for RMS power normalization).

Sign up for our newsletter

Stay up to date on upcoming trends and latest applications.

Sign up for our newsletter