Impedance Analysis with an E5061B ENA Vector Network Analyzer
Application Notes

Impedance Analysis with an E5061B ENA Vector Network Analyzer

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Table of Contents

  • Introduction
  • Performing Impedance Analysis with the E5061B
  • Examining Five Commonly Used Measurement Methods
  • Selecting the Best Method for Your Application
  • Ensuring Accurate Results: Calibration and More
  • Examining Real-world Examples
  • Conclusion
  • Related Information

Introduction

There are often times when you need to quickly check or evaluate the DC to RF performance of components and circuits which were previously analyzed with a dedicated impedance analyzer. The convenience of impedance analysis capabilities built into a network analyzer would address this scenario by providing enough dynamic range and RF performance to ensure reliability, signal integrity, and EMI performance of your system.

Whether you need to measure basic S-parameters or analyze device or circuit impedance, a vector network analyzer (VNA) with the right mix of speed and performance will give you an edge. In R&D and on the production line, Keysight ENA vector network analyzers provide the throughput, repeatability, and reliability you need to perform accurate, dependable tests that transform parts into competitive components. The E5061B ENA vector network analyzer covers 5 Hz up to 3.0 GHz (Option 3L5), addressing low-frequency (LF) and radio-frequency (RF) measurements. With the impedance analysis capability (Option 005), the E5061B addresses a wide range of LF and RF applications.

This application note describes five common impedance analysis approaches used with impedance analyzers and network analyzers. It also describes how and when to use the E5061B for impedance analysis. Major topics include test ports, impedance analysis capabilities, measurement methods, and calibration techniques. The note concludes with a variety of examples ranging from basic component measurements (e.g., inductors and capacitors) to in-circuit impedance measurements.

Performing Impedance Analysis with the E5061B

The E5061B offers versatile network analysis capabilities from 5 Hz to 500 MHz (Option 3L3), 1.5 GHz (Option 3L4), or 3.0 GHz (Option 3L5). Comprehensive LF measurement capabilities such as built-in 1 MΩ inputs are seamlessly integrated with the high-performance network analyzer architecture. Core features include S-parameter test ports (50 Ω), a gain-phase test port (switchable between 50 Ω and 1 MΩ), and a DC bias source (up to ±40 Vdc).

Adding impedance analysis:

For an E5061B configured with any of the LF-RF network analysis options—3L3, 3L4, or 3L5 (“3Lx” collectively)—Option 005 provides impedance analysis (ZA) firmware. The combination of NA and ZA capabilities further enhances the analyzer’s versatility as a general-purpose R&D tool.

Adding the ZA firmware enables the analyzer to measure impedance parameters of electronic components such as capacitors, inductors, and resonators. Additional functionality includes fixture compensation and equivalent circuit analysis. Biased impedance measurements are possible with the built-in DC bias source provided by options 3L3, 3L4, and 3L5.

With any of the frequency options, E5061B-005 cannot match the ultimate overall performance of a dedicated impedance analyzer. However, it does enable you to apply measurement methods, calibration techniques, and fixturing choices that provide comparably accurate impedance measurements.

Comparing the test ports:

The E5061B-3Lx is equipped with two types of test ports: S-parameter and gain-phase. Let’s take a closer look at each type.

The S-parameter test ports (Port 1 and 2) have a built-in 50-Ω test set that covers the analyzer’s full frequency range (Figure 1). In the RF range, the E5061B provides excellent performance equal to that of similar analyzers. The E5061B particularly excels in the LFrange, providing coverage down to 5 Hz and better dynamic range in the low-to-middle range below 10 MHz for a thorough evaluation of one- and two-port devices such as filters, amplifiers, transformers, and antennas.

The gain-phase test port has reference and test receiver inputs with the ability to switch between 50 Ω and 1 MΩ input impedance (Figure 2). These are used to analyze the frequency response of low-frequency devices and circuits such as op-amps and the control-loop circuits of DC-to-DC converters.