Manuel Carmona, radio frequency business development and product manager, Johanson Technology
Integrated passive components (IPCs) have been attracting a great deal of interest due to the miniaturisation of wireless devices and the need to increase reliability of signal conditioning in their radio frequency integrated circuits (RFICs), in terms of, for example: filtering; impedance matching; differential to single-ended conversion; and coupling.
An IPC is a compact electronic sub-system that combines multiple discrete passive components into a single surface mounted device. It is manufactured via low-temperature cofired ceramic (LTCC) technology, allowing the constituent passive components to be layered three-dimensionally, and delivers the same functionality and performance as 10–40 individual discrete surface mount components (SMCs).
A diagram of an IPC; the constituent passive components are layered three-dimensionally.
In other words, the entire front end of a PCB—between the wireless radio frequency (RF) chipset and the antenna—can be produced in a single, ultra-low profile (0.35–1.0 mm total thickness) package that is more than 80 percent smaller than the same circuit afforded by the more conventional discrete SMCs. If one is looking from above, only three chips can be seen, namely the wireless RF chipset, the IPC and the antenna. This much smaller, compact design means that the overall size of the PCB can be significantly reduced.
Another important benefit of IPCs is that they deliver greater reliability than discrete SMCs. This creation of a circuit in a small package can all but eliminate variability and potential points-of-failure. Much of the variability of discrete SMCs is due to the individual variance of each component. This is, of course, multiplied depending on the number of components; and it only takes one underperforming link in the circuit to cause the entire front end of a PCB to fail.
IPCs are available for almost any type of passive circuit, including low- and high-pass filters, diplexers, triplexers, impedance matched baluns, balun filters, band pass filters, couplers and other custom signal conditioning circuits.
LTCC technology
The process used for manufacturing IPCs is similar to that used for manufacturing multi-layer SMD component parts such as capacitors and inductors. However, LTCC technology allows circuits to be embedded in as many as 40 separate layers in a three-dimensional package that is still very low profile.
Johanson Technology has used its proprietary LTCC manufacturing process to develop a line of small yet highly reliable IPCs for RF systems. These components operate over several bands from 300 MHz to 10 GHz, covering cellular, Digital Enhanced Cordless Telecommunications (DECT), 802.11 (a, b and g) wireless local area network (WLAN), Bluetooth and Global Positioning System (GPS) applications.
The LTCC manufacturing process is extremely precise and repeatable, making it possible to stay within the limits of alignment, variations and so forth, and resulting in robust and consistent RF circuitry.
All IPC packages are tested to ensure that their components meet RF performance requirements and, if necessary, adhere to Federal Communications Commission (FCC) and European Telecommunications Standards Institute (ETSI) criteria.
Matched-filter balun IPCs
A balun is an electrical device that converts between a balanced (differential) and unbalanced (single-ended) signal. It can take many forms and may include devices that also transform impedances.
As many wireless RF chipsets have differential (two-pin) outputs—an RF input and output— that connect to a single-ended antenna, the signal needs to be converted from differential to single-ended in a specific impedance ratio. Most of the time, these wireless RFICs have a non-standard complex impedance, which IPCs match for optimum power efficiency. Some baluns are also combined with a bandpass, low-pass or high-pass filter.
Johanson Technology works with the chipset manufacturer to achieve an impedance conjugate match and thus create a matched-filter balun IPC that is optimised and has a matching part number for each specific chip. The collaboration begins at the reference design stage of development to ensure that the IPC will not only work but also comply with any emission requirements. This simplifies and speeds up adoption of the chipset in the market.
Markets
As IPCs require significantly less PCB space, smaller miniature wireless devices with RFICs and therefore smaller form-factor products can be realised.
The size and placement of passive components on PCBs are critical, because as the trend towards miniaturisation gathers momentum, it is becoming increasingly difficult for these boards to accommodate as many components. Design engineers are therefore looking to component manufacturers to deliver solutions that occupy next to no real board space.
The automotive industry is using IPCs on account of their increased reliability for a range of on-board systems, including cellular, Wi-Fi, Bluetooth, satellite radio and GPS, as well as key fobs. As such, IPCs are designed to meet the Automotive Electronics Council (AEC) AEC-Q200 qualification standard for passive parts.
Another key benefit of IPCs is that by enabling use of smaller PCBs, they allow products to feature slimmer, sleeker profiles. Furthermore, by eliminating components on a 10:1 or greater basis, they reduce products’ overall weight. These factors have major implications for next-generation implantable medical devices, portable electronics, and smart wearables, for example, rings, bracelets, shoes, jeans, shirts and other apparel.
A selection of Johanson Technology IPCs
Johanson Technology