移至主內容
Search

Measurement of High-Q Capacitors

Related products: MFIA, MF-IA

Application Description

Measuring high-Q capacitors with the MFIA

Figure 1: Schematic showing an SMD capacitor mounted on a 4-terminal MFITF carrier, which is inserted into the MFITF and connected to the MFIA.

High-performance components are critical when developing faster and smaller electronic devices. A prime example is the capacitor, which is often called upon to ensure an extremely low equivalent series resistance (ESR). Capacitors with this property have a high quality factor Q or, equivalently, low loss or low dissipation D. As Q represents the efficiency of the capacitor, that is, the ratio of energy stored to energy dissipated per cycle, it is related to the ESR (RESR) as Q = 1/(ω C RESR), where ω is the angular frequency and C is the capacitance.

High-Q capacitors are required for RF power stages, demanding filter applications, and as bypass elements. Manufacturing high-Q capacitors requires high-temperature sintering with careful control of the dielectric layer thickness, the dielectric constant of the ceramic material, and the volumetric form factor defining the effective area. This process leads to a manufacturing variability such that even capacitors with the same part number can exhibit very different Q values. For this reason, optimal circuit design necessitates the ability to measure Q, D and the ESR over the full working frequency range of the component.

Measurement Strategies

The Q factor of a capacitor can be measured with a multi-instrument set-up comprising a resonant line, an RF signal generator and an RF voltmeter. This method is not suitable for frequencies below 100 MHz, and requires interpolation and post-processing to extract accurate values. A vector network analyzer can be used between 1 MHz and 3 GHz, but its accuracy is low and post-processing is also required to calculate Q, D, or the ESR.

A single-instrument strategy takes advantage of an impedance analyzer such as the MFIA. With the MFIA Impedance Analyzer, it is possible to obtain direct measurements of Q, D and the ESR without calibration. The sample is mounted on a carrier and inserted into the MFITF Impedance Test Fixture as shown in Figure 1. This method is easy to set up and use, and affords high accuracy for frequencies between 1 mHz and 5 MHz. Swept measurements allow Q to be measured as a function of frequency at values over 105 (see Figure 2).

LabOne Sweeper module displaying the Q factor of high-Q capacitors

Figure 2: Screenshot of the LabOne Sweeper module displaying the Q factor of eight different SMD capacitors. The traces are color-coded as shown in the History tab to the right.

The Benefits of Choosing Zurich Instruments

  • You can measure the Q factor, the dissipation, and the ESR of your discrete capacitors accurately and at the operation frequency of your device over the range of 1 mHz to 5 MHz.
  • The MFIA comes with the low-parasitic MFITF Impedance Test Fixture to ensure calibration-free measurements, but it is also possible to use your existing third-party fixtures with the user-compensation tool of the LabOne software, which is also included with the MFIA.
  • Displaying multiple impedance parameters as a function of frequency is straightforward thanks to the LabOne Sweeper tool, whereas measurements at a fixed frequency can take advantage of the LabOne Plotter tool.
  • The MFIA can be integrated into larger setups thanks to the five APIs provided with LabOne.

Start the conversation

Videos

MFIA Impedance Analyzer overview

未發表
MFIA Impedance Analyzer Overview

What makes a great impedance analyzer?

未發表
What makes a great Impedance Analyzer?
Contact Us