A Compact LTCC Balun for Bluetooth/WLAN Application

In this paper, a 2.4-2.5 GHz Marchand balun,which uses semi-lumped concept and LTCC technology, has been newly designed,simulated, and fabricated. The measured results and the results of computer simulation show a good match. The balun is implemented with a ten-layer commercial low temperature co-fired ceramic (LTCC) process. Between 2.4 GHz and 2.5 GHz ,the measured insertion loss is small than 1.3 dB and return loss is better than 20 dB. The amplitude imbalance is less than 0.25 dB and the phase balance is within 180° ±4.5°. The overall dimension is as small as 2 mm × 1.25 mm × 0.96 mm.