Multi-Beam RF Aperture Using Multiplierless FFT Approximation

TL;DR

This paper introduces a low-complexity, multiplierless 8-point FFT approximation for RF beamforming, enabling efficient multi-beam RF receivers with reduced power consumption and hardware complexity.

Contribution

A novel 8-point FFT approximation using only 26 additions, suitable for low-power RF multi-beam systems, implemented in CMOS and FPGA.

Findings

Achieves eight RF beams closely matching traditional FFT patterns

Operates at bandwidths of 588 MHz (CMOS) and 369 MHz (FPGA)

Uses only 26 additions, no multipliers

Abstract

Multiple independent radio frequency (RF) beams find applications in communications, radio astronomy, radar, and microwave imaging. An $N$-point FFT applied spatially across an array of receiver antennas provides $N$-independent RF beams at $\frac{N}{2}\log_2N$ multiplier complexity. Here, a low-complexity multiplierless approximation for the 8-point FFT is presented for RF beamforming, using only 26 additions. The algorithm provides eight beams that closely resemble the antenna array patterns of the traditional FFT-based beamformer albeit without using multipliers. The proposed FFT-like algorithm is useful for low-power RF multi-beam receivers; being synthesized in 45 nm CMOS technology at 1.1 V supply, and verified on-chip using a Xilinx Virtex-6 Lx240T FPGA device. The CMOS simulation and FPGA implementation indicate bandwidths of 588 MHz and 369 MHz, respectively, for each of the independent receive-mode RF beams.