Broadband Multilayer Capacitors
Cap Value (pF)
Passive Plus, Inc. (PPI) has developed a series of Broadband Capacitors available in 5 different case sizes: the 01005BB, 0201BB, 0402BB, 0603BB, and the 0805BB. Values available are 10nF (103) and 100nF (104). These capacitors are intended primarily for coupling RF signals or, occasionally, for bypassing them to ground, while blocking DC. The applications for which they are intended require small, surface-mountable devices that provide low RF impedances, i.e., low insertion losses and reflections, across extremely large RF bandwidths and temperatures typically ranging from -55 to +125° C.
Small, single layer capacitors, apart from not being surface-mountable, usually do not have sufficiently large capacitance values to cover the required frequency range, which may extend from the tens or hundreds of kilohertz to tens of gigahertz. Ordinary multi-layer capacitors, when operated over these ranges, display “parallel resonances,” narrow frequency bands over which they have high impedances and insertion losses. The Passive Plus “BB” series overcomes these objections to achieve bandwidths as high as — in the case of the 0201BB104 — a remarkable 16 KHz to >50 GHz. Insertion Loss <1db, with a WVDC of 16V.
Applications for the BB series are primarily found in the so-called “signal integrity” market:
Optoelectronics / high-speed data
ROSA/TOSA (Transmit / Receive optical subassemblies)
SONETS (Synchronous Optical Networks)
Broadband test equipment
Broadband microwave and millimeter wave amplifiers and oscillators
In general, best results are achieved by capacitors that are close in width to that of the transmission line trace. Most trace widths on commonly used substrates that must function well above 12 GHz lie in the 8- to 24-mil range, and so 0402 and 0201 SMT devices are well suited to the applications.
To reiterate, customers requiring surface-mountable, 10 nF or 100nF capacitors that provide resonance-free, low insertion loss, low reflection operation over extremely large RF bandwidths will be well served by Passive Plus’s BB series.
Modelithics 90-Day Free Trial CAD Models
Passive Plus, Inc. (PPI), a Modelithics® Vendor Partner (MVP), is now offering design engineers a Free 90-Day Trial license for the Modelithics PPI Component Library. This will provide PPI customers access to extremely accurate scalable simulation models for Passive Plus capacitors with advanced features that enable a more precise and rapid design process.