Holistic design strategy for high-selectivity low-loss integrated millimetre-wave image-reject filters

To alleviate practical limitations in the design of millimetre-wave on-chip image-reject filters, systematic design methodologies are presented. Three low-order filters with high-selectivity and low-loss characteristics are designed and compared. Transmission zeroes are created by means of a quarter-wave transmission line (filter 1) and a series LC resonator (filters 2 and 3). Implemented on silicon germanium, the filters occupy 0.125, 0.064 and 0.079 mm² chip area including pads. The measured transmission losses across 81-86 GHz E-band frequency range are 3.6-5.2 dB for filter 1, 3.1-4.7 dB for filter 2 and 3.6-5 dB for filter 3 where rejection levels at the image band are >30 dB.