Miniaturized Differential Filters For C- and Ku-Band Applications

We have developed a new set of differential filters suitable for C and Ku-Band applications. The filters are integrated on 500 ¿m-thick high-resistivity silicon substrates which are compatible with the new SiGe processes. A lumped-element approach is used to result in a very small size and high-Q metal-air-metal (MAM) capacitors are integrated in the filter structure for a low-loss design. The measured insertion loss of differential 6 GHz and 12 GHz 10% bandwidth 2-pole Chebyshev filters with an area of 2.3 × 1.5 mm2 and 1.8 × 1.1 mm2 is ¿3.6 dB and ¿4 dB, respectively. An image reject filter at 6 GHz resulted in an image rejected of 20 dB and an insertion loss of ¿3.6 dB. These filters are ideal for integration in modern-day SiGe and CMOS transceivers for wireless LAN and satellite communications.