Reconfigurable phase-linearizer for 2-D IIR RF-to-bits antenna-array digital beam filters

Radio-frequency (RF) digital phased array antennas are highly-useful for achieving electronically-scanned smart antenna apertures with applications in radar, signal intelligence, microwave and mm-wave imaging and wireless communication systems. However, digital phased array algorithms are of high computational complexity, which leads to correspondingly high circuit complexity in a VLSI implementation. A 2-D IIR beam space-time plane-wave digital filter can achieve the required electronically-scanned RF beams albeit at an order of magnitude lower circuit complexity compared to phased arrays at the cost of non-linear phase response. The proposed method approximately rectifies the non-linearity in the phase response using an FFT-based phase compensation method which linearises the response at higher frequencies close to the Nyquist limit where the phase non-linearity is worst in the beam filter response. FPGA prototypes using a Xilinx Virtex-4 Sx35-10ff668 device on an XtremeDSP Kit-4 are provided, which show real-time operation at up to 315 MHz.