3-to-5GHz 4-channel UWB beamforming transmitter with 1° phase resolution through calibrated vernier delay line in 0.13μm CMOS

Narrow-band phased-array transmitters provide an efficient way of obtaining higher power through spatial combining and achieving higher transmitter EIRP. They also provide beamforming and beam-steering capabilities [1]. However, the commonly used phase shifter or LO phase-shifting techniques at RF become less attractive for 3-to-5GHz UWB due to their lossy, bulky and narrowband characteristics. On the other hand, True-Time-Delay (TTD)-based beamforming transmitters employed at baseband have been popularly adopted due to UWB's inherent digitally intensive nature [2]. However owing to the limited achievable delay resolution and delay accuracy, the reported phase resolution is normally limited to 10°. This work introduces a 3-to-5GHz UWB beamforming system spanning from −45° to 90° phase range with 1° phase resolution. The fine delay resolution is achieved through a Vernier delay line without the need of advanced technology. The delay is calibrated with a ΔΣ DLL.