Beamformer with constant-Gm vector modulators and its spatial intermodulation distortion
article
Spatial interference rejection in analog adaptive beamforming receivers can improve the distortion performance of the circuits following the beamforming network, but is susceptible to the nonlinearity of the beamforming network itself. This paper presents an analysis of intermodulation product cancellation in analog active phased array receivers and verifies the distortion improvement in a four-element adaptive beamforming receiver for low-power applications in the 1.0-2.5-GHz frequency band. In this architecture, a constant-Gm vector modulator is proposed that produces an accurate equidistance square constellation, leading to a sliced frontend design that is duplicated for each antenna element. By moving the transconductances to RF, a fourfold reduction in power is achieved, while simultaneously providing input impedance matching. The 65-nm implementation consumes between 6.5 and 9 mW per antenna element and shows a +1 to +20 dBm in-band and out-of-beam third-order intercept point due to intermodulation distortion reduction. © 2017 IEEE.
Topics
Analog beamformingcompression point (CP)intercept pointinterference nullingmixerphase shifterphased arrayreceiverspatial filteringswitched capacitorvector modulatorAntenna phased arraysAntennasBeamformingFrequency bandsIntermodulation distortionModulatorsInterference suppressionIntermodulationMixers (machinery)Receivers (containers)Active phased arrayAdaptive BeamformingDistortion performanceInput impedance matchingInter-modulation productsLow power applicationSpatial interferenceThird order intercept pointsCompression pointsIntercept pointsSwitched capacitorBeam forming networks
TNO Identifier
954877
ISSN
00189200
Source
IEEE Journal of Solid-State Circuits, 52(3), pp. 735-746.
Publisher
Institute of Electrical and Electronics Engineers Inc.
Article nr.
7805216
Pages
735-746
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