A 0.6–4.0 GHz RF-Resampling Beamforming Receiver with Frequency-Scaling True-Time-Delays up to Three Carrier Cycles

True-time-delays enable wideband analog and hy-brid beamforming by mitigating the beam squint problem. This paper reports a true-time-delay beamforming receiver supporting delays up to three carrier-frequency cycles. The implementation is the first published work in which the delays scale with the carrier frequency. The scaling enables true-time-delays for large arrays at low-GHz frequencies where long delays are required due to λc/2 antenna spacing. The delays are implemented through delayed resampling of a passive mixer’s discrete-time output. Driving the mixers with pulse-skipped local oscillator (LO) signals allows the delay range to exceed one carrier cycle. A polyphase receiver structure prevents aliasing of noise and unwanted tones caused by LO pulse-skipping. Our prototype implementation demonstrates squint-free beamforming for an 800 MHz instantaneous RF bandwidth. The proposed true-time-delay is efficient for large arrays since the power consumption per antenna is only 5–13 mW across the 0.6–4.0 GHz frequency range. The prototype was implemented in 28-nm FD-SOI CMOS, and the die area including bonding pads is only 1.2 mm2.