Digitally Controlled Oscillator Topologies for mm-Wave Pulsed Coherent Radar

Abstract: The advancement of future generations of wireless communication and radar sensing warrants the need for mm-wave digitally controlled oscillators (DCOs) with high-frequency trade-offs in consideration. The purpose of this project is to investigate DCO topologies inspired from scientific literature. The DCO is an electronic component that takes a digital code as input to tune the output operation frequency. Acconeer's application, a pulsed coherent radar system, sets unconventional performance requirements on the DCO compared to continuous wave systems. A specific type of oscillator core, namely the cross-coupled differential-pair harmonic oscillator, has been investigated. The performance of this oscillator is subject to special trade-offs in the DCO implementation. A strategy of multiple stages was used to guide the work. First, possible solutions were crudely investigated, then promising solutions selected, and finally pre- and post-layout simulation results of said solutions were provided. Five solution alternatives were identified and benchmarked with respect to a digital equivalent of the cross-coupled differential-pair LC-VCO. These solutions present different opportunities to relax trade-offs in the design of the DCO. Benchmarking the post-layout results of the solutions with literature revealed competitive performance, considering requirements set by the radar application, which is the context of this work. The analysis of this investigation provides a foundation and suggestive guidelines of future action for Acconeer. This work also captures the state-of-the-art of DCOs for pulsed coherent radar, priming further research within the field.