Ka-band 5-bit TTD Phase Shifter with Miniaturized Equivalent Delay Lines

This paper proposes a Ka-band 5-bit switched dual-side microstrip line true-time-delay phase shifter in 28 nm bulk CMOS process. The dual-side microstrip line has vertical arrangements of delay lines and reference lines, which allow implementing compact switched-line phase shifter. The delay cells are implemented with lumped elements which are miniaturized with low self-resonance-frequency inductors. These are very small but have many parasitic capacitances of which resonances are used to make time delays. With these techniques, the proposed TTD phase shifter controls 36.9 ps with the core area of 0.07 mm
²
. This is the smallest size among the reported Ka-band TTD phase shifters.