Analog Interference Suppression Circuits for Converged RF SystemsONR White Paper tracking number 23-000005741
Abstract
The Naval Tactical Grid (NTG) will require efficient and dynamic use of the electromagnetic spectrum for reduced SWaP of RF systemsthough next-generation radios and phased arrays that enable coexistence between applications (e.g. jamming and sensing). Extremely flexible radio front-end concepts have been around, where software-defined radio (SDR) is the most promising implementation. However, their dynamic frequency, protocol, and modulation format capabilities still have not found widespread use in high data-rate consumer products or many military applications. The critical component of any modern SDR RF front-end is the analog-to-digital converter (ADC), and generally, the total RF bandwidth is not usable for most practical receivers since its dynamic range is insufficient. Interference is one of the most critical limitations for system coexistence and can be intentional or unintentional, self or externallycaused. RF front ends and beamforming networks perform isolation between T and R paths through nonreciprocal, switching, or filtering components to achieve multiple concurrent missions from a single aperture. We propose to develop integrated dynamic analog interference suppression circuits that scale in power and frequency to enable interference-resilient RF front ends that can relieve the ADC dynamic range requirements of SDRs applied to NTG and allow for the reception of weak signals. The proposed approach cascades isolation components such as active circulators, switches, and tunable active notch filters to achieve in-band and out-of-band self-interference suppression. The solution is well suited for monolithic microwave integrated circuit (MMIC) integration in advanced semiconductors such as GaN for high power handling and linearity in the presence of strong jammers. The proposed MMICs can be integrated inphased-array beamforming networks, and extended to reduced SWaP beamformer feed design for electrically small tactical platform arrays. The research technical objectives are to design and implement two front-end circuits for in-band and out-of-band self-interference suppression, using MMIC active circulators and tunable active filters; to design an MMIC implementation of a tunable active circulator for isolation recovery due to scan reflection coefficient mismatching to be integrated with active tunable filters. The initial phase targets X-band (8-12GHz), and upon successful demonstration, we plan to scale to millimeter waves (Ka to W band) and lower frequencies (S and C band) where tradeoffs in footprint will be considered between quasi-monolithic and hybrid implementations. We also propose demonstrating operation with signals of various instantaneous bandwidths and peak-to-average ratios (PARs), adding components that provide resilience to impedance mismatch, enabling high IP3 by integrating into GaN, and ensuring stability with gain in both transmit and receive paths. The circuits will be fabricated and characterized various conditions to investigate the trade-off between circuit complexity, power consumption, nonlinearities, noise, and dynamic range performance. The University of Colorado, Boulder, and the PI#s group are actively engaged with NSWC Crane through the NITE WATCH and STARRY NITE programs, with GaN MMIC designs in the Qorvo GaN25, GaN15 and GaN09, as well as the HRL T3 40-nm and NGC 90-nm processes covering C through W bands (~3-110GHz). We can leverage access to state-of-the-art domestic foundries to implement the proposed interference-resilient front ends across all frequencies relevant to the NTG.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 15, 2023
- Source ID
- N000142412042
Entities
People
- Zoya Popovic
Organizations
- Office of Naval Research
- Regents of the University of Colorado
- United States Navy