Project Details
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Fundamentals of THz Circuits and Systems in Advanced SiGe HBT Technologies

Subject Area Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
Term from 2019 to 2023
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 419161860
 
Final Report Year 2025

Final Report Abstract

The project investigated the potential and limitations of the world-fastest SiGe HBT experimental technology development in the frequency allocation spectrum currently reserved for III-V technologies. As at the project beginning, the technology was missing any kind of circuit performance verification and device model evaluation at THz frequencies, substantial effort needed to be undertaken in all scientific disciplines responsible for the final model-hardware correlation. These disciplines span across device modeling, simulation methodology, and measurement techniques with a suitable set of challenging de-embedding steps. All these aspects went through a detailed background analysis to understand their impact on the measured reported performance of various broadband circuit blocks and subsystems to be able to define THz-specific design techniques beyond the current state-of-the art. In particular, the nonlinear frequency-dependent large-signal and noise models for the devices operating not only in the forward-active range at the highest speed were investigated in detail but also for wide range of bias points, including saturation. New layouts of the standalone devices and the major core circuit blocks were developed with the aid of full-wave EM simulations resulting in considerably improved model-hardware correlation at THz frequencies. Further, an innovative approach to design on-chip passives with the aid of buried asymmetric broadside-coupled lines was applied to demonstrate fundamentally-operated circuit blocks, including LNAs and PAs, with an absolute bandwidth near in excess of 100 GHz. On the subsystem level, room-temperature operation of the THz power detectors and D-to-J band total-power radiometers with a sensitivity level suitable for passive imaging was proved for the first time. The highest level of circuit complexity was achieved with the design of the complete polarization MIMO directconversion IQ TX/RX chipset operating fundamentally around 240–300 GHz with its basic RF performance verified in a free-space line-of-sight configuration. The circuits were fabricated in early access runs of a new 130 nm SiGe BiCMOS technology developed at IHP. This technology provides HBTs with peak ft values of 470 GHz and peak fmax values of 650 GHz surpassing the performance of all previously available BiCMOS processes. The fabrication of integrated circuits for a wide range of applications within this project facilitated model-hardware correlation at an early stage of the technology development thus supporting the development of accurate compact models as well as the definition of process specifications that are most appropriate for future applications up to the THz band. The results achieved within the project frame, demonstrate the potential of SiGe HBT technology as a future platform for THz circuit integration.

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