A TTD-Based Fast Precise Localization Enabled by Passive-Active Signal Combiner With Negative-Capacitance Stabilized RAMP

Fast and precise localization is one of critical requirements awaiting solutions in radar and communication systems. Spatio-spectral mapping has been proven as an effective methodology to estimate the angle-of-arrival (AoA) with low latency. In this work, we achieve a low AoA estimation error compared to prior integrated works by implementing a large delay-bandwidth (BW) product in the spatial signal processor (SSP) which correspondingly challenges the hardware design for multi-antenna analog/hybrid arrays. This work presents a two-channel 1.5-GHz BW true-time-delay (TTD)-based signal combiner with maximum 10 ns delay range demonstrating fast chirp-based source localization [also, beamtraining (BT)] for the first time. The measured AoA estimation error is significantly reduced from ±7.8° to ±1.1° with 15X increase in delay. This system-level solution is enabled by an integrated multistage switched-capacitor-array (MS-SCA) architecture including digitally controllable clock generator for large TTD, and a passive-active ring-amplifier (RAMP)-based signal combiner to overcome the BW trade-offs in conventional amplifier-based signal combiners. Further, a reduced gate-load bootstrapped switch and a negative-capacitance stabilized RAMP is proposed to support large BW operation. The proposed TTD-based MS-SCA achieves large delay-BW products of 15. The core design of this system consumes 37.3 mW/channel and 0.45 mm2 in 65 nm CMOS.