Integrated passive components simplify signal conditioning

16th May 2019
Lanna Cooper

Integrated Passive Components (IPCs) are attracting increasing interest due to the miniaturisation of wireless devices, as well as the need to increase reliability of signal conditioning in RF circuits such as filtering, impedance matching, differential to single ended conversion and coupling. IPCs are essentially electronic sub-systems that combine multiple discrete passive components into a single surface mounted device.

Manufactured using Low Temperature Co-fired Ceramic (LTCC) technology that allows the passive components to be layered 'three-dimmensionally', IPCs deliver the same functionality as 10-40 individual components, while dramatically reducing the board space required. 

With this approach, the entire front-end between the RF chipset and the antenna can be manufactured in a single, ultra-low profile (0.35-1.0mm total thickness) package that is less than 20% the total size of the same circuit comprised of discrete components.

“If you were to look at the circuit from above, you would only see three chips: the RF wireless chip, the IPC and the antenna,” explained Manuel Carmona of Johanson Technology. “The design is very clean and really small. You can make the overall PCB size much smaller using IPCs while maintaining high wireless performance.”

Industries already adopting IPC technology include automotive, medical, mobile electronics and 'smart' wearables.

For customers less concerned with board space or overall size, IPCs deliver another significant benefit - greater reliability. By creating a literal circuit within a small LTCC package, variability and potential points-of-failure are all but eliminated when compared to mounting many discrete components. A single integrated package of matching components also all but assures compliance with FCC or ETSI requirements.

“A lot of the variability of 'solo' surface-mounted components is due to the individual variance of each component. When you multiple that by 10-20 components, you just need one weak link in the RF chain for the entire front-end to fail,” said Carmona.

Carmona said 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 to manufacture IPCs is similar to the technology already used to create multi-layer SMD component parts, such as capacitors and inductors. However, LTCC manufacturing allows circuits to be embedded in as many as 40 separate layers in a three-dimensional package that is still very low profile.

Using this manufacturing process, Johanson Technology has developed a line of small, highly reliable IPCs for RF systems manufactured with a proprietary LTCC process. These components operate over several bands from 300MHz to 10GHz covering Cellular, DECT, WLAN, Bluetooth, 802.11 (a, b and g) and GPS applications.

Each integrated package is thoroughly 100% RF tested to ensure all the components are working properly and are integrated together.

“Because of the LTCC manufacturing process is extremely precise and repeatable, we can stay within the manufacturing limits of alignment, variations, and so forth, so you get really consistent, robust, RF circuitry,” said Carmona.

As a result, Johanson Technology is able to guarantee the IPC is a passive sub system that is guaranteed to pass its RF performance requirements with FCC and ETSI and any other emission regulation.

Match-filter baluns
One standout IPC offering is Johanson Technology’s line of Matched-Filter Baluns. 

A balun is an electrical device that converts between a balanced (differential) and unbalanced (single-ended) signal. The component can take many forms and may include devices that also transform impedances.

Because many RF wireless chipsets have differential (two pins) 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 the IPC’s match for optimum power efficiency. Some baluns are also combined with a bandpass, low pass, or high pass filters.

To accomplish a impedance conjugate match, Johanson Technology works with chipset OEMs to create a specific Match-Filter Baluns with a matching part number for each chip. The collaboration begins with reference designs during development to simplify and speed-up adoption of the chipset in the market.

“The IPC is basically a plug-and-play solution,” explained Carmona. “By working with the leading chipset manufacturers, we have already completed the R&D to ensure it is optimised for that specific chip. Not only will it work, but it will comply with any emission requirements.”

Because IPCs require much less board space, smaller miniaturised devices with RF circuitry can be designed and smaller form-factor products created.

“With PCB real estate at a prime, the size and placement of the passive components are critical because as everything gets smaller it becomes increasingly difficult to place more components on the board,” explained Carmona. “Therefore, design engineers are looking to component manufacturers to deliver miniaturised solutions that occupy next to no real board space.”

Beyond size, a smaller PCB can also impact the aesthetics of a product, allowing for slim, low profiles. The elimination of components on a 10:1 or greater basis also reduces the overall weight of devices, even if that savings is measured in tenths of grams.

These factors have major implications for next generation smart wearables (rings, bracelets, shoes, jeans, shirts and other apparel), implantable medical devices and portable electronics.

As it relates to greater reliability, Carmona said the automotive industry is already utilising IPCs for on-board cellular, WiFi, Bluetooth, satellite radio and GPS systems, as well as key fobs. As such, IPCs are designed to meet AEC-Q200 standards.

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