A ΣΔ-Modulated Linear-in-dB Attenuator for On-Chip Power Detection with 0.12dB Resolution in RF SOI CMOS Switch Technology

In this work, an innovative scheme to boost the resolution of the variable radio-frequency (RF) attenuator is proposed and examined. The attenuator stage modulated by a first-order sigma-delta modulator (ΣΔM) shows a linear-in-dB attenuation profile for the average RF power with high resolution. The proposed attenuator provides a low-power solution for accurate on-chip power measurement with zero quiescent current. The implemented attenuator shows an effective attenuation tuning step size of 0.12 dB from 700MHz to 6 GHz with a power consumption of only 41.4 µW. The device is designed and fabricated in 90nm RF SOI CMOS switch technology.