A Low-Power, High-Resolution Successive Approximation RF Reflectometer
Year: 2024
Type: article
Abstract: This article presents a monolithically integrated radio frequency (RF) scalar reflectometer based on a successive approximation register (SAR) approach with boosted measurement resolution. The limiting factors of the SAR-based architecture are investigated and the corresponding solutions are brought up accordingly for the improvement. The directional coupler used in the reflectometer adopts a reconfigurable design with which the directivity can be optimized for various frequency bands by loading the tuning ports with impedance tuning network. The device directly converts the return loss of the load ($\mathbf {\lvert {\Gamma }_{L} \rvert }$) into a digital output code by controlling the attenuator with the SAR codes. By modulating the attenuator with a$\Sigma \Delta $-modulator ($\Sigma \Delta $M), the step size of the attenuation can be reduced to as low as 0.25 dB, reducing the quantization error and boosting the resolution of the SAR-based reflectometer. The device is designed and implemented in a 90-nm RF SOI CMOS switch technology, occupying a core area of$700\times 1000~{\mu}{\mathrm {m}}$. The implemented reflectometer demonstrates a measurement error of 0.061 in terms of$\mathbf {\lvert {\Gamma }_{L} \rvert }$for VSWR ranging from 1.4 and 20 while consuming a supply current of$86~{\mu }\text {A}$in conversion mode and$12.4~{\mu }\text {A}$in idle mode from a dc supply of 1.8 V.
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $2,495
OpenAlex ID: W4404520570