Project Details
Projekt
Regenerative, Beyond-fmax, 3D Printed Terahertz Multichannel Camera Transceivers - TeraCaT II
Subject Area
Communication Technology and Networks, High-Frequency Technology and Photonic Systems, Signal Processing and Machine Learning for Information Technology
Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
Term
since 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 468813342
The THz range enables high-resolution imaging. The challenges include sufficient amplification. In conventional circuits, this is limited by the small signal gain (SSG). Gains of > 6 dB per stage are only possible for frequencies < 1/3 of the maximum transistor oscillation frequency (fmax ). Amplifications > 30 dB can only be realized by cascading many stages, high DC power and bulky horn antennas. In order to solve these fundamental problems for THz camera receivers, we investigated super-regenerative oscillators (SRO) in TeraCaT, which only require a SSG of slightly above 1 in order to achieve a high large signal gain (LSG) due to the positive feedback. In SiGe BiCMOS, we demonstrated a LSG of 50-60 dB at 182 GHz. Using a novel subharmonic-pumped SRO concept, we demonstrated an outstanding mixing gain from 600 to 200 GHz of 37 dB at PDC of only 12 mW. These results are groundbreaking for efficient FMCW radars at frequencies above the semiconductor technology limitations. Novel signal distribution networks based on 3D printed dielectric waveguides allow low-loss and low-dispersion transmission of THz signals with low complexity and high flexibility. In the new continuation project TeraCaT II, we will extend the 600 GHz TeraCaT receiver to a multi-channel capable 600 GHz camera transceiver. This will involve gaining knowledge from circuits to system design. In order to achieve high gain for the transmitter at 600 GHz, we are also utilizing the SRO advantages. A novel approach for integrating a large number of transmitter elements into the receiver array will be investigated. By power accumulation and generation of large virtual apertures a high sensitivity and resolution is realized. By means of variable phase shifts in transmit signals and different transmit-receive configurations, we generate random illumination patterns despite static arrays. Thanks to numerous receivers, this enables image reconstruction using compressed sensing algorithms, using fewer individual measurements, without array movement or beam steering. Additively manufactured, dielectric mirror lines increase the scalability of the coherent local oscillator distribution network through laser structuring, so that complicated placement of additional waveguide elements or machining post-processing is completely eliminated for the first time, even for large arrays. Novel, low-loss, tree-like branched antenna arrays made of monolithic 3D stereolithographically printed antennas replace the vertical dielectric waveguide antennas that were previously fitted individually. Overall, an efficient, scalable, complex 3D THz transceiver array concept at 600 GHz will be experimentally demonstrated for the first time, which requires only a few technology building blocks. The SRO theory will be extended with regard to THz systems. In TeraCaT II we will combine again the complementary competencies of the groups of Vossiek (RF systems, algorithms and antennas) and Ellinger (IC design).
DFG Programme
Priority Programmes
Co-Investigator
Dr.-Ing. Christian Carlowitz
