Knowles – The Advantages of Knowles Precision Devices’ Broad Capacitors

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High-speed broadband and fiber optic devices used across a variety of communication and military and aerospace applications require circuits that couple RF signals. Since this involves removing the DC component and allowing only the high-frequency AC component to pass or bypass, this can be a complicated process. The blocking capacitor needs to present a near reflectionless transition at the frequency the line is seeing and at a bandwidth that allows the entire signal to pass without degradation.

While there are a number of broadband blocking capacitors on the market today, many struggle to provide low insertion loss over a broad frequency range. But not Knowles Precision Devices’ Broadband Milli-Cap® capacitor. Milli-Cap is designed to be the ideal single-piece construction surface mount (SMT) capacitor for broadband applications up to 50 GHz (most competitors only support up to 40 GHz). Milli-Cap’s voltage rating is the highest in the market while also offering the lowest insertion loss (see Figure 1).

Mili-Cap Knowles

Figure 1. This insertion loss plot shows two different Milli-Cap capacitors operating reliably up to 50 GHz.

Milli-Cap comes in three case sizes, which is the most options available for a high-performance SMT broadband blocking capacitor (Figure 2).

Mili-Cap Knowles2Figure 2. This chart shows the dimensions of the three different Milli-Cap capacitor offerings and a diagram of a Milli-Cap capacitor. 

Milli-Cap capacitors at each of these three case sizes are constructed using a variety of Class I and Class II dielectric materials depending on the temperature needs of the application. Milli-Cap is also orientation insensitive, which means there is no wrong way to attach the capacitor to your assembly. Additionally, Milli-Cap capacitors can be attached to a soft or hard substrate using a conductive epoxy or solder.

To summarize, the key features of our broadband Milli-Cap blocking capacitors are as follows:

  • 0201, 0402, and 0602 footprints
  • Low-loss, High Q
  • Very low series inductance
  • Ultra-high series resonance
  • Matches typical 50Ω line widths
  • Behaves like an ideal capacitor
  • Single-piece construction
  • Orientation insensitive

In addition to our Broadband Milli-Cap blocking capacitors, we also offer another ultra-broadband DC blocking option – Opti-Cap, which provides an even broader frequency range than Milli-Cap from 16 KHz to 50 GHz.

Learn more about broadband Milli-Cap or explore purchasing options through DigiKey or the SLC Design Engineering Kit available through RFMW.