A Distributed Variable Delay Line for Wideband Beam-Formers

A fully integrated CMOS wideband distributed variable delay line for time array beam-formers is presented. The delay line works over a full differential mode, and the delay cell function is based on differential amplifiers with active inductive peaking loads. A delay resolution of 15 ps is obtained with a maximum delay capability of 150 ps . The designed active delay line provides 3 scanning angles with 8.6 degrees of spatial resolution. This delay line is applicable for a 4 channel beam-former with an operational bandwidth of 500 MHz centered at 5 GHz. Our active delay line consumes up to 352 mW of power from 2.5 V supply. The circuit is simulated in standard 0.25 μm BiCMOS process and occupies 252 μm × 123 μm of silicon area.