A 4-bit ultra-wideband beamformer with 4ps true time delay resolution

This paper documents an ultra-wideband (UWB) fully integrated beamformer which features controllable true time delay and power gain. The UWB beamformer accomplishes 4-bit delay variation with 4 ps resolution, 5 dB gain variation in 1 dB steps, and a -3dB gain bandwidth of 11.2 GHz. Overall operation is achieved by the integration of a three-bit tapped delay trombone-type structure with 4ps variable delay resolution, a one-bit 32ps fixed delay coplanar-type structure, and a variable gain distributed amplifier. The prototype chip fabricated in a 0.18 mum BiCMOS SiGe process occupies 1.6mm2 of silicon area and consumes 125 mW from a 2.5 V supply at the maximum gain setting of 14.2 dB