  A current-mode CMOS design is proposed for realizing receive mode multi-beams
in the analog domain using a novel DFT approximation. High-bandwidth CMOS RF
transistors are employed in low-voltage current mirrors to achieve bandwidths
exceeding 4 GHz with good beam fidelity. Current mirrors realize the
coefficients of the considered DFT approximation, which take simple values in
$\{0, \pm1, \pm2\}$ only. This allows high bandwidths realizations using simple
circuitry without needing phase-shifters or delays. The proposed design is used
as a method to efficiently achieve spatial discrete Fourier transform operation
across a ULA to obtain multiple simultaneous RF beams. An example using 1.2 V
current-mode approximate DFT on 65 nm CMOS, with BSIM4 models from the RF kit,
show potential operation up to 4 GHz with eight independent aperture beams.
