An Offset-Canceling Approximate-DFT Beamforming Architecture for Wireless Transceivers

We describe a current-mode multi-beam beamforming approach for 5G wireless applications based on a low-complexity approximate-DFT (a-DFT). Dynamic current mirrors are used to cancel errors in the current copying and scaling operations required to realize a-DFT matrices, thus resulting in an accurate and scalable architecture. The circuit design for the case of 8-point a-DFT has been validated with transistor-level simulations in the UMC 0.18 μm CMOS process.