We present the design and development of a compact, broadband balun based on a quasi-lumped LC transformer. The balun is constructed on a multilayer liquid crystal polymer substrate. The balun has a wide range of operating frequency from 0.9 to 3.6 GHz. Within this operating band, the balun achieves a measured insertion loss of less than 1 dB, a measured return loss of better than 10 dB, a measured amplitude imbalance of less than 1 dB and a measured phase imbalance less than 7°. This balun has an extremely compact size of 2 × 2.5 mm2. Copyright © 2013 Wiley Periodicals, Inc.

We present the design and development of a compact wide stopband bandpass filter using novel quasi-lumped LC resonators on a defected ground structure. The resonators are built on a multilayer organic substrate and are coupled to external circuits by shunt-inductive impedance inverters. Experimental results show that the filter has a center frequency of 960 MHz and a 3 dB fractional bandwidth of 8%. The filter has a wide stopband that has an out-of-band rejection of better than 30 dB up to five times of the center frequency. The size of the filter is 5.4 mm × 27 mm or 0.027λg × 0.132 λg, where λg is guided wavelength at 960 MHz. © 2014 IEEE.