Sub-GHz LTCC filter for TI's CC112x transceiver series

June 06, 2013 // By Graham Prophet
Murata's LFD21 dual matching filter is designed specifically for sub-1 GHz wireless applications using the CC112x series of low power transceivers from Texas Instruments.

Believed to be the world’s smallest filter available, measuring just 2.00 x 1.25 x 0.7 mm this miniature LTCC (low temperature co-fired ceramic) surface mounted filter takes up much less board space than a discrete design and has been approved by Texas Instruments for use with its CC112x transceivers. With such small dimensions the extremely compact filter frees up board space for additional features. The LFD21868MMF has a nominal operating frequency centred on 891.50 MHz ±23.50 MHz and can accommodate up to 500 mW transmit power output. This tiny space saving device ensures board space, BOM count and engineering effort is kept to a minimum. Compared with a traditional inductor and capacitor design, the filter module replaces more than 10 discrete components.

Insertion loss is typically better than 1.73 dB transmit and 2.67 dB receive. The antenna port matches to a nominal impedance of 50 Ω.