Title :
A 5-6-GHz polyphase filter with tunable I/Q phase balance
Author :
Sanderson, D.I. ; Svitek, R.M. ; Raman, S.
Author_Institution :
Wireless Microsystems Lab., State Univ., Blacksburg, VA, USA
fDate :
7/1/2004 12:00:00 AM
Abstract :
A tunable polyphase filter with integrated input and output buffers was designed and fabricated in a 0.4 μm SiGe BiCMOS technology with a 5-6-GHz bandwidth. Series tunable capacitors (varactors) provide phase tunability for the differential quadrature outputs of the polyphase filter. The tunable phase can be used to improve image rejection in Weaver or Hartley architectures, or mitigate in-phase and quadrature (I/Q) phase error in direct conversion or low-IF receivers. The die area of the fabricated circuit with pads is 920 μm× 755 μm. Based on measurements, approximately 15/spl deg/ of I/Q phase imbalance can be tuned out using the fabricated polyphase filter, proving the concept of tunable phase. To the authors´ knowledge, this is the first reported tunable I/Q balance polyphase network.
Keywords :
BiCMOS analogue integrated circuits; Ge-Si alloys; circuit tuning; field effect MMIC; microwave filters; semiconductor materials; varactors; 0.4 micron; 5 to 6 GHz; BiCMOS technology; Hartley architectures; I-Q balance polyphase network; SiGe; Weaver architectures; differential quadrature outputs; direct conversion receivers; image rejection; in-phase error; integrated input buffers; integrated output buffers; low-IF receivers; phase imbalance; phase shifter; phase tunability; polyphase filter; quadrature phase error; series tunable capacitors; signal generation; tunable I-Q phase balance; varactors; wireless local area network; Bandwidth; BiCMOS integrated circuits; Capacitors; Filters; Germanium silicon alloys; Image converters; Q measurement; Silicon germanium; Tunable circuits and devices; Varactors;
Journal_Title :
Microwave and Wireless Components Letters, IEEE
DOI :
10.1109/LMWC.2004.831779
