Programa del congreso

This paper presents the design and measurement results of a high-power, ultra-wideband amplifier based on the recently available 150-nm GaN-on-SiC process technology offered by Leonardo foundry. The designed power amplifier (PA) adopts a single-stage non-uniform distributed PA topology comprising ten active devices within a 5×5 mm2 die. To facilitate future system integration, the PA prototypes have been validated in three configurations: on wafer, wire-bonded to a test fixture, and packaged into a plastic QFN. The obtained results of the on wafer and bare die tests show that the designed PA can deliver an average output power higher than 39 dBm from 4 GHz to 18 GHz, with an average associated power added efficiency of 20 %. This amplifier has been designed to validate this new European manufacturing process and demonstrate its potential for the development of components for future radar and electronic warfare systems.

High electron mobility transistor (HEMT)-based amplifiers hold the state-of-the-art in cryogenic low-noise performance, but their reactive input impedance imposes a stark trade-off between input return loss and optimum noise match, making them non-ideal for wide-band designs at sub-GHz frequencies. Meanwhile, SiGe heterojunction bipolar transistor (HBT)-based amplifiers have the ability to span multi-decade bandwidths that reach close to DC, while having also been proven to be a compelling alternative for cryogenic low-noise designs in the low-GHz range. With previous work having shown some mass-produced commercial-off-the-shelf (COTS) HBTs to excel in the low-noise realm, the possibility of using commercially available devices for cryogenic low-noise is explored further, resulting in a 0.3-3.3 GHz SiGe HBT-based cryogenic low-noise amplifier (CLNA) incorporating bare-die devices from a European foundry achieving 6.4 K average noise temperature and 34 dB gain with |S₁₁| better than -9.7 dB when measured at 17 K.

This work explores the capability of nano-diodes fabricated in AlGaN/GaN heterostructures, controlled by a gate electrode, to operate as zero bias (current or voltage) detectors

at room temperature, by means of on wafer characterization up to 43 GHz. These devices are usually referred as Gated Self-Switching Diodes (G-SSDs). A quasi-static analytical model based on the measured DC curves is able to predict the behavior of the device at low frequencies (1 GHz). The current responsivity shows a maximum for a gate voltage just above the threshold when working as zero voltage detector in drain injection (DI) configuration. The frequency performance of the G-SSDs has been evaluated when working both as current and voltage detector and also when the RF power is injected in the gate port (GI). The potential to operate at higher frequencies has been validated up to 300 GHz in free space.

The RAEGE project, a collaboration between Spain and Portugal, aims to establish a geodetic VLBI network of radiotelescopes with cryogenic low-noise 2-14 GHz receivers as part of the VGOS initiative, enhancing space geodetic measurements with millimeter-level accuracy. Additionaly, in the framework of BRAND-EVN project, broadband low-noise receivers covering 1.5–15.5 GHz for radioastronomy VLBI have been developed, incorporating frequency converters compatible with DBBC3 backends. This paper presents the design, fabrication, and characterization of frequency downconverters for these receivers, focusing on the so-called B-band unit, which downconverts the 4–8 GHz band to an intermediate frequency range (DC–4 GHz). The design employs microstrip technology and precision-machined enclosures to ensure optimal impedance matching, gain control, and minimal noise contribution. Performance evaluation, including S-parameters, gain, P1dB, and noise figure measurements, confirms compliance with VGOS and BRAND specifications. The results validate the downconverter’s efficiency and underscore key advancements in broadband signal processing for both astronomical and geodetic VLBI applications.