Design of CMOS Integrated Q-enhanced RF Filters for Multi-Band/Mode Wireless Applications

Recent developments in portable applications and systems have lead to a significant in wireless standards. Therefore, cost efficiency of CMOS technology implementation has been greatly enhanced with the emergence of multi-mode wireless applications. Now multimode/multi-band receivers are designed based on the scheme of reuse[1]-[3]. They avoid using multiple chipsets and can be made tunable which makes them more efficient in term of area and power consumptions. In a flexible receiver front-end, analog baseband filtering is a key task as it is used to select the required information under desired channel bandwidth. A large tuning range of the band-pass filter should be required for various wireless applications. To meet different specifications for the desired channel in multimode receivers, there has been a tremendous amount of research [1-6] effort aimed at improving the performance of integrated reconfigurable continuous-time (CT) filters in recent years. However, due to the open-loop operation nature, Gm-C filters generally use operational transconductance amplifier (OTA) driving a capacitor load at the cost of moderate linearity, sensitivity to parasitics. Moreover, the major disadvantage of OTA is the large distortion caused by the nonlinear behavior of the transistors involved. To enhance the linearity of the OTA and avoid potential stability problems, an approach to linear Gm-C integrators with inherent CMFB is developed based on the techniques of the cross-coupled differential pairs and source degeneration with passive resistors. In Section 2, the high linear transconductor Gm is presented. The design of the Chebyshev bandpass filter is discussed, as such the simulated results of the bandpass filter are given in Section 3. The conclusion is given in Section 4.