Introduction
Wireless connectivity is at every corner of our daily life. Communication is not only between people but also people-to-machine and machine-to-machine. Things are getting connected and smarter. Many of these connections need be wireless.
From great data rate video applications to low data rate remote controls, from kilometer away wireless monitor connections to meter distance PAN Bluetooth headsets, various technologies have been developed for many wireless connectivity occasions.
Many of the wireless connectivity applications are size limited, such as wearable device, RFIC and etc. To reduce size and cost, IPD (Integrated Passive Device) can be helpful.
IPD has become a viable technology to meet the ever growing need to reduce size and cost, increase functionality for RF front-ends. With the mature and advanced IC fabrication process, IPDs can be developed significantly smaller, thinner, with greater performance and consistency than conventional passive devices.
Xpeedic provides full kinds of passive devices with IPD technology, including filters, diplexers, baluns, couplers, attenuators and etc. with packages such as wire-bonding/flip-chip die, WLCSP and etc. for typical wireless communication application.
Front-End Module Block Diagram
The following diagram demonstrates a typical WLAN FEM. Many passive parts of the front end can be developed with IPD, helping size reduction and function integration.
Noise Filtering
Signal comes with noise, harmonics, spurs and other unwanted spectrum parts. Filtering is a useful and often adopted solution to improve signal to noise ratio. Low pass filter often gets smaller footprint and lower insertion loss when compared with band pass filter. But in many cases, band pass filter is needed for its better noise suppression and low frequency band filtering.
Typical Xpeedic IPD BPF performance is plotted as below. More detailed information can be found in Xpeedic website.
Diplexer
WLAN adopts ISM (industry, science, medical) bands, 2.4GHz and 5GHz mostly. A diplexer can be used between FEM and dual band antenna to multiplex 2.4GHz and 5GHz frequency bands. Dual band WLAN antenna can be used together with the diplexer to replace the two single frequency antenna used for 2.4GHz and 5GHz separately, to save space and cost.
Typical Xpeedic IPD diplexer performance is plotted as below. More detailed information can be found in Xpeedic website.
Balun
RF front end circuits are mostly single ended, digital ⁄ analog circuits are often differential, a balun is needed between them to transform from balanced to un-balanced. Additional function such as out-of-band suppression and impedance transformation is also sometimes integrated into balun devices.
Xpeedic IPD baluns have great balance performance which is a key specification for balun device. A typical Xpeedic IPD balun gets an amplitude unbalance<0.1dB and a phase unbalance <2°.
Packaging
Based on IC process, IPD devices are ready for packaging with other IC dies and integrated as one SiP (System in Package) module which is the main application method of IPD.
IPD die can be packaged aside other dies or stacked upon or under other dies to get more compact packaging. Flip-chip or wire-bonded, IPD can be integrated into various RF FEMs such as switch modules or PA modules.
IPD die can be packaged alone as a discrete SMT passive device, ready for PCB level usage. Several IPD dies can be packaged together to compose a passive system, integrating complex passive functions such as filtering-matching-balun, matching-diplexer, antenna feeding matrix and etc.
Below charts show several IPD packaging methods, and many more options are available regarding packaging and SiP, application specifically, please contact Xpeedic sales for more information.
