04.04.2026 –, Test Chamber 01
Open-source chip-design initiatives and EDA tools are enabling affordable, workflows from SystemVerilog to GDS-II, making custom ASICs accessible even to hobbyists. As a demonstration, a collaboration between JKU Linz and the University of Würzburg realized the first fully integrated WSPR transmitter IC using the Tiny Tapeout 130 nm mixed-signal process, eliminating the need for PCs, microcontrollers, or FPGAs. The chip combines a digital subsystem that generates WSPR symbols using CORDIC and sigma-delta modulation with an analog RF chain that performs IQ modulation, filtering, and amplification, proving that real-world amateur radio applications can be implemented entirely with open-source tools.
Initiatives such as Google Skywater, IHP130, and Tiny Tapeout, coupled with the collaboration of open-source tools like LibreLane or Yosys, are poised to democratize chip design. This approach eliminates the need for commercial EDA tools, making the production of custom chips using multi-project wafers and chips significantly more affordable – even for hobbyists. This presentation will elucidate the intricacies of such a workflow, from the design level entry using system Verilog to the generation of GDS-II files. As an example for a HAM-Radio application an WSPR-Transmitter is implemented on a chips just by using open-source EDA-Tools and workflows.
Weak Signal Propagation Reporter (WSPR, pronounced “whisper”) is a well-known tool in amateur radio for analyzing the propagation of shortwave signals. These signals are refracted by the ionosphere, allowing them to travel remarkable distances around the globe, even with just small transmit powers of just a few milliwatts. The tool, developed by Nobel laureate Joe Taylor (K1JT), typically requires a PC running dedicated software and a shortwave transmitter. While numerous embedded implementations have been created in the past—using microcontrollers or FPGAs — there has so far been no integrated circuit that provides native WSPR functionality.
Until now! In a collaboration between JKU Linz and the Julius-Maximilians-Universität Würzburg, we have implemented a fully WSPR-capable transmitter in the TT-Sky25b process—realized as a 130 nm analog mixed-signal design via Tiny Tapeout. The design shown in the image, consists of two major components: a digital subsystem that generates the transmit symbols from the message information (operator callsign, power level, and location), and an analog subsystem that performs the actual RF modulation. The digital part uses a CORDIC IP block and a sigma-delta modulator to produce a complex analog baseband signal. This signal is then modulated by an IQ-Modulator, filtered, and amplified by a fully analog RF chain.
Matthias (DL9MJ) is a professor of computer engineering at the University of Würzburg. In his free time, he is interested in HAM radio and jazz. He is the Youth and Education Chair at the German Amateur Radio Club DARC.