Research On Wideband Analog Multi-Beamforming Technology

Humans have been trying to understand the universe we live in.Even the world's largest single-caliber radio telescope FAST,which is currently built in China,can't meet specific needs.So the SKA project came into being.This is a multidisciplinary project where the use of signal processing techniques involves beamforming techniques.On the one hand,this technology can replace the traditional mechanical swing arm type antenna system,has greater flexibility,realizes the receiving and amplification of spatial directivity signal,suppresses interference signals from undesired directions,and also functions as a spatial filtering;on the other hand,the structure provides a higher signal-to-noise ratio than a single-antenna system of the same aperture size.Nowadays,beamforming technology has been widely used in radar,military communications and other fields,and is facing great development in the fields of commercial communication,astronomy,biomedicine and other fields.Based on the SKA project,this thesis designs a broadband multi-beam forming chip for low intermediate frequency.The chip uses an active delay network architecture based on the gm-C first-order order all-pass filter,which can support 4 inputs and 4 outputs simultaneously.The active delay unit greatly reduces the chip area compared to the use of LC passive devices.The circuit implementation of the chip includes a low noise amplifier,a true-time-delay unit based on the gm-C first-order all-pass filter,combiners,and output-matching units.The entire system is fully differential,which achieves higher signal amplitude than single-ended circuits,and provides better linearity and SNR performance.Second,it is highly resistant to crosstalk.Thirdly,EMI performance is better than the single-ended counterpart;finally,the difference also suppresses even-order harmonics.The chip was designed by HHNEC 0.18?m Si Ge Bi COMS process and the layout was completed,whose area is 2.0mm × 1.99 mm.The fully integrated beamforming chip maintains flat gain and group delay over ultra-wide bandwidth(0.35-1.5 GHz).Achieving a minimum resolution of 100 ps,a uniform linear array with an antenna spacing of 10.5 mm,depending on the configuration,provides four scan angles of ±75° and ±18° for efficient synthesis and amplification of spatial signals.