High-selectivity E-Band image-reject filters in SiGe technology

To alleviate practical limitations in the design of mm-wave on-chip image-reject filters, systematic design methods are presented. Two low-order filters with high-selectivity and low-loss characteristics are compared. The transmission zeroes are created by means of a quarter-wave transmission line (filter 1) and a series LC resonator (filter 2). Implemented on SiGe, they consume only 0.125 and 0.064 mm2 chip area including pads. The measured transmission losses across 81–86 GHz E-Band frequency range are 3.5–5 dB (filter 1) and 3–4.5 dB (filter 2) where rejection at the image frequency is greater than 30 dB.