Design of multiband baluns on liquid crystalline polymer (LCP) based substrates

Baluns operating at multiple frequency bands can result in a reduction in the size of multiband RF front-ends. This paper presents novel multiband balun topologies, using both distributed as well as lumped components. Using LCP packaging technology, baluns operating simultaneously at the 930 and 2000 MHz frequency bands have been fabricated. Measurements show -14.5 dB and -32.4 dB return loss in the lower and upper bands. The phase and amplitude imbalances are less than 2.5/spl deg/ and 0.6 dB in each band.