An Electronically Tunable Bandpass BAW-Filter for a Zero-IF WCDMA Receiver

This paper presents for the first time an integrated tunable RF filter using bulk acoustic wave (BAW) resonators designed to be used in a zero-lF W-CDMA receiver between the LNA and the mixer. The presented filter offers a reduced sensitivity to process and temperature variations thanks to its tunability. The tuning is achieved through additional passive components (Q-enhanced inductors and varicaps). Measurements confirm that the prototype filter permits to correct a 0.6% error on the BAW piezoelectric layer thickness. It consumes 7 mW for a 2.14 GHz center frequency in a 0.25 mum SiGe:C BiCMOS process. Good in-band linearity and noise performances have also been obtained