Researchers unveil programmable ramp generator for agile radar and clock synthesis

A new arXiv paper from Pranjal Mahajan and seven co-authors details the design and analysis of a fully digital Programmable Ramp Generator (PRG) for frequency synthesizers. The proposed modular architecture combines a phase-accumulator-based frequency sweep generator, a Delta-Sigma Modulator (DSM), and a Multi-Modulus Divider (MMD), giving digital control over ramp slope, bandwidth, and duration. This eliminates the need for analog tuning elements, enabling highly reconfigurable chirp synthesis for Frequency-Modulated Continuous-Wave (FMCW) radar, spread-spectrum clock generation, and high-end test instrumentation.

The paper's core contribution is a rigorous analysis of three circuit-level constraints that previous work ignored: MMD octave-boundary behavior under dynamic updates, divider-synchronous timing requirements, and DSM limitations on step duration and achievable slope. By jointly addressing these, the authors define a complete PRG design space and offer a systematic algorithm that maps application-level specifications directly to hardware parameters. This makes the architecture practical for designers, not just a theoretical concept.

To validate their methodology, the team implemented a 16-bit PRG in TSMC 65nm CMOS and verified it across 18 ramp profiles. Real-time operation was also confirmed through hardware prototyping on a Xilinx Spartan-7 FPGA. The result is a low-cost, flexible building block that can be dropped into radar sensors, clock generators, and measurement systems—paving the way for software-defined analog functions in next-generation RF front ends.