University of Twente Student Theses


Design of an RF receiver in BiCMOS implementing beamforming to reject interference

Kleinsmann, E.M. (2013) Design of an RF receiver in BiCMOS implementing beamforming to reject interference.

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Abstract:This thesis deals with the implementation of an RF frontend for a digital beamforming Software Defined Radio receiver. Initial beamforming is implemented in the frontend to reject interferers, which would otherwise desensitise the frontend. A beamforming strategy is presented which creates a beam by applying independent phase shifts to the input signals. This way the radiation pattern of the beam is altered resulting in varying beamshapes and differently placed zeros. This beam is then used to create a set of 4 orthogonal beams, which, together, prove to preserve all information, so further beamforming can be performed in software. Interferers can be rejected in the frontend by ‘capturing’ the interferer in 1 of the 4 beams, therewith not affecting the other 3 beams. A circuit level implementation re-using the LO phases already created for harmonic rejection to implement beamforming and therewith saving the implementation of extra phase shifters is proposed. Circuit simulation shows an improvement of the signal-to-interferer ratio of the created beams by 14 to 33 dB in a worst-case scenario in comparison to when no initial beamforming is implemented in the frontend.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:53 electrotechnology
Programme:Electrical Engineering MSc (60353)
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