ESCALAS

The DLR-funded “Enhanced Self-CALibrating Amplifier components for Space (ESCALAS)” project is focused on developing cost-effective, space-saving and power-efficient RF modules operating from 15 GHz up to and beyond 60 GHz, specifically tailored for next-generation active-antenna array satellite communication systems. The project partners are the German Aerospace Center (DLR), Tesat-Spacecom GmbH (TESAT), Leibniz Institute for High Performance Microelectronics (IHP), Karlsruhe Institute of Technology (KIT) and University of Stuttgart.

Active-antenna array satellites incorporate numerous RF chains, each comprising amplifiers, phase shifters, and antennas. By precisely controlling the gain and phase response of these RF chains, the antenna array can form transmission and reception beams in specific directions. This beamforming capability enhances antenna directivity and significantly boosts antenna gain, ultimately enabling high-throughput data communication. Growing the size of active-antenna arrays and operating in the harsh environment of space introduce additional challenges. Since a satellite’s payload power budget is strictly limited, active components that draw DC power such as phase shifters and amplifiers must be designed for maximum energy efficiency without compromising mission requirements. Moreover, maintaining reliable long-distance links demands transceivers capable of delivering high output power. Consequently, High-Power Amplifiers (HPAs) and Traveling-Wave Tube Amplifiers (TWTAs) are used to meet these power requirements. However, at elevated power levels, transistor non-linearities can give rise to intermodulation distortion and adjacent-channel interference. These effects degrade the bit-error rate and reduce achievable data rates. To extend the linear operating range of these amplifiers, analog or digital predistortion techniques are commonly employed.

Moreover, as the satellite traverses its orbit, it encounters extreme temperature swings and intense radiation that can shift the behavior of RF components. To compensate for these changes, an on-board Built-In Self-Test (BIST) calibration module is required, continuously monitoring RF module performance and executing in-orbit self-calibration. To ensure long-term reliability, the RF and BIST modules must be developed and validated under the extreme thermal and radiation conditions encountered in space.

Within the ESCALAS project, the implementation of linearized channel amplifiers (LCAMPs) using IHP’s state-of-the-art SiGe BiCMOS MMIC technology for both K-band (18–26 GHz) and Q/V-bands (37–66 GHz) was aimed. LCAMPs comprise two RFIC modules, a Channel amplifier and a Linearizer combined with an integrated BIST module for in-orbit performance monitoring and self-calibration. Key project objectives include:

• Miniaturization & Cost Efficiency: Leveraging advanced SiGe-BiCMOS MMIC process to reduce size and manufacturing costs.
• Enhanced Functionality: Enabling fully automated, on-board self-calibration of transceiver chains.
• Broad Scalability: Covering all pertinent satellite-communication frequency bands in the millimeter-wave spectrum.

By exploring these innovative circuit paradigms, ESCALAS paves the way for next-generation “New Space” RF front ends.

• Channel RFIC (CRFIC) Development: Consisting of low-noise amplifier, amplitude equalizer, phase shifter, variable-gain amplifier (VGAs), and medium-power amplifier (MPA) stages.
• Broadband Linearizer (LRFIC) Development: Implementing an analog predistortion RFIC designed to deliberately generate third-order intermodulation (IM3) products with precisely controlled phase and amplitude, enabling effective cancellation of corresponding IM3 distortions at the output of a high-power amplifier (HPA) or traveling-wave tube amplifier (TWTA). This approach aims to significantly extend the linear operating range of the amplifier. In addition, the linearizer will feature an integrated built-in self-test (BIST) calibration module to facilitate autonomous in-orbit self-calibration. The Institute of Robust Power Semiconductor Systems (ILH) is responsible for the development of the linearizer.
• End-to-End LCAMP Demonstration: Achieve Technology Readiness Level 4 by validating the full RF chain comprising the CRFIC, LRFIC, and self-calibration functionality.
• Radiation Hardness Validation: Subject the developed RFICs to rigorous radiation testing to verify their resistance and ensure suitability for space deployment

will be available soon !