An Embedded Calibration Structure for mm- Wave Multi-probe Reflectometers

In this paper, an embedded calibration structure for millimeter-wave (mm-wave) multi-probe reflectometers is presented. The proposed structure is designed using on-chip components, thereby eliminating the need for the commonly used bulky and costly mm-wave on-wafer calibration equip-ment. This calibration structure can operate concurrently with the reflectometer, enabling compensation for temperature and process variations. For a proof-of-concept, the reflectometer and proposed calibration units are designed and simulated for E-band in a 65 nm standard CMOS process. The proposed calibration unit, composed of three replications of the reflectometer and on-chip passive components, occupies an area of 100 um ×500 um <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(0.05 \ \text{mm}^{2})$</tex>. The simulations for complex impedance detection using the designed structure, show a maximum magnitude and phase error of 1.8 dB and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4^{\circ}$</tex> at 60 GHz and 0.9 dB and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2.5^{\circ}$</tex> at 90 GHz, respectively.