Some important aspects on the design of active microwave filters using standard RF silicon process technologies

In this paper, we investigate if two types of recursive topologies that previously have been utilized to realize active microwave filters in GaAs can also be used on silicon with comparable performance and using smaller circuit area. First, a 6.8-1.2GHz SiGe BiCMOS tunable recursive filter realized using lumped on-chip 3dB couplers is evaluated (circuit size is 2.34mm²). Higher on-chip inductor losses than expected are found to limit the gain of this filter design. Secondly, we present a C-hand RF CMOS recursive filter design that is based on an active impedance matching technique. The sue of the CMOS filter is equal to half of that of the SiGe BiCMOS filter (1.2mm²). Furthermore, the area of the CMOS filter is close to a third of that of a previously reported recursive filter design implemented in GaAs with a comparable RF performance.