RF Microwave / Thin Film

Practical Capacitor Tolerance Selection for Coupling, DC Blocking and Bypass Applications Abstract: Proper selection of suitable capacitor tolerances is governed to a great extent by the type of application under consideration. This point should always be taken into account when designing for the best balance between cost and performance. For example, DC blocking, coupling and bypassing applications are not very sensitive to the variations in capacitor value that are due to the choice of wide spread tolerances. In contrast, applications such as filtering and matching will usually require narrow spread capacitance tolerances in order to meet the specific demands of those designs.

ESR Losses in Ceramic Capacitors Abstract: In the world of RF ceramic chip capacitors, Equivalent Series Resistance (ESR) is often considered to be the single most important parameter in selecting the product to fit the application. ESR, typically expressed in milliohms, is the summation of all losses resulting from dielectric (Rsd) and metal elements (Rsm) of the capacitor, (ESR = Rsd + Rsm). Assessing how these losses affect circuit performance is essential when utilizing ceramic capacitors in virtually all RF designs.

Considerations for Optimal Capacitive Coupling Abstract: Capacitors used in coupling and DC blocking applications serve to couple RF energy from one part of a circuit to another and are implemented as series elements. Proper selection of coupling capacitors insures the maximum transfer of RF energy. All capacitors will block DC by definition; however, considerations for satisfying the requirements of a coupling application depend on various frequency-dependent parameters that must be taken into account beforehand.

Capacitors in Broadband Applications Abstract: Proper selection of capacitors for RF broadband applications requires careful evaluation of frequency dependent parameters and certain design requirements. In today’s rapidly expanding RF and microwave markets, numerous designs must operate over multiple octaves of frequency spectrum. Some of the more common of these include broadband bias networks such as transistor emitter and FET source bypassing, transistor collector and FET drain feed structures, as well as interstage RF coupling, DC blocking, and wideband impedance matching.

Capacitor Pi Network for Impedance Matching Application Note 026 Abstract: Designing matching networks is one of the key aspects of RF/Microwave design. A lossless network that matches an arbitrary load to real impedance has to have at least two reactive elements. However, two elements do not give control over the bandwidth and the degree of match simultaneously. Three-element matching networks, i.e. Pi- and Teenetworks, provide additional control of the frequency response.

RF Ceramic Chip Capacitors in High RF Power Applications Abstract: In today’s world of wireless communications systems there are a myriad of high RF power applications that necessitate the use of high quality specialized ceramic chip capacitors. These demands require the designer to carefully account for factors such as device power dissipation and maximum current and voltage ratings as well as thermal resistance and temperature rise during normal circuit operation. This article highlights some of the most essential elements needed for selecting capacitor products suitable for these applications.