An ultra-compact integrated millimeter-wave coupled-line resonator and a bandpass filter in silicon-germanium technology

An ultra-compact integrated resonator and bandpass filters (BPF), in silicon-based technology, are presented for millimetre-wave applications. The resonator consists of two broadside-coupled lines in opposite orientations. Using this resonator, a first-order and a second-order BPFs were also designed. To prove the concept, three prototypes of each of the resonator and the first-order BPF were fabricated using a standard 0.13-μm SiGe process. The measured results show that the resonator has an attenuation of 13.7 dB at the resonance frequency of 57 GHz, while the BPF has a centre frequency of 31 GHz and an insertion loss of only 2.4 dB. Excluding the pads, the chip size of both the resonator and the BPF is extremely compact, only 0.024 mm² that is equivalent to 0.001 λg². The unloaded Q factor of the filter is higher than other state-of-the-art designs.