Brian A. Floyd

A 6-to-31-GHz reflection-mode -path filter is implemented in 45-nm SOI technology. The filter includes an on-chip hybrid coupler with through and coupled ports terminated with four-phase passive mixers. Each mixer provides a high impedance in-band and a matched, 50- impedance out-of-band (OOB) that is provided by the ON-resistance of the switches. As such, in-band signals are reflected by the mixers, and OOB signals are absorbed. This enables reflection-mode bandpass filtering of the signal, with the center frequency set by the local-oscillator frequency. To increase selectivity, an active baseband (BB) load with adjustable bandwidth can be enabled to provide a second-order capacitive response, which increases the roll-off to 12 dB/octave. Measurements show that the filter can be tuned across 6–31 GHz with a maximum 3-dB RF bandwidth of 0.47 GHz for the passive BB and either 0.22 or 1.22 GHz …

A design methodology for the synthesis of baseband circuits for higher-order reflection-mode N-path filters (RMNFs) is presented. Beginning with a linear time-invariant (LTI) model, equations are formulated that provide intuition for the designer with regard to signal and noise transfer through the RMNF. Building upon the mathematical foundation of the LTI model, an interdependence between signal and noise is explored and addressed. Furthermore, two baseband synthesis approaches are presented and connected with other state-of-the-art works. Finally, a 12-18GHz RMNF design with third-order selectivity (18dB/octave) is performed with analytical, simulated, and measured hardware results to validate the presented methodology.

This article presents multi-band direct-conversion receivers (RXs) with frequency-translated negative feedback. The forward path includes a low-noise transconductance amplifier (LNTA) followed by four-phase passive mixers that drive baseband amplifiers. A feedback path employs tunable resistor banks attached to additional four-phase passive mixers, allowing tunable, frequency-selective input matching around a wide range of local oscillator (LO) frequencies. The passive mixers are driven by 25% duty-cycle, non-overlapping quadrature LO waveforms, and two different methods are presented for generating such waveforms. Two RX variants, differing in their LO generation schemes, are fabricated in 45-nm SOI CMOS. The first operates from 6 to 30 GHz, exhibiting greater than 25-dB gain and 4.1–10.5-dB noise figure (NF). A second operates from 10 to 50 GHz, achieving greater than 18-dB gain with 7.1–17-dB NF across …

Hierarchical code-modulated embedded test (CoMET) is introduced to characterize and calibrate scaled phased arrays in parallel using orthogonal code modulation with scalar detection. Hierarchical testing can reduce CoMET test time without sacrificing accuracy. A 64-element 28 GHz phased-array receiver is used to demonstrate the technique, where the array is divided into four- or eight-element sub-arrays and measured in a hierarchical manner. Hierarchical CoMET is validated against VNA measurement to achieve 1.5 degrees and 0.25 dB phase and gain RMS error across 64 elements and 64 phase settings. Electrically-swept beams are improved after calibration based on hierarchical CoMET.

This paper studies the phase and gain control dependencies of a variable gain amplifier (VGA) and a vector interpolator phase shifter (VIPS) within a 20 GHz beamforming receiver. First, the mechanisms of gain control and phase variation in a classic current-steering VGA are analyzed and design techniques are proposed such that the gain-dependent phase variations (GDPV) introduced by the amplifiers are well balanced. Second, similar analysis is performed to evaluate GDPV within a vector interpolator, where we show how the same techniques only partially apply due to the cross-coupling structure of the interpolator’s VGAs. We evaluate our techniques within a 20 GHz beamforming receiver IC realized in GlobalFoundries 45 nm RFSOI. Very low GDPV is observed within the VGA, with less than 0.3-deg. root-mean squared phase variation for a 9 dB gain control, whereas the VIPS achieves worst-case GDPV of …

National radio dynamic zone (NRDZs) are intended to be geographically bounded areas within which controlled experiments can be carried out while protecting the nearby licensed users of the spectrum. An NRDZ will facilitate research and development of new spectrum technologies, waveforms, and protocols, in typical outdoor operational environments of such technologies. In this paper, we introduce and describe an NRDZ concept that relies on a combination of autonomous aerial and ground sensor nodes for spectrum sensing and radio environment monitoring (REM). We elaborate on key characteristics and features of an NRDZ to enable advanced wireless experimentation while also coexisting with licensed users. Some preliminary results based on simulation and experimental evaluations are also provided on out-of-zone leakage monitoring and real-time REMs.

Code-modulated embedded test (CoMET) has been investigated for simultaneous testing and calibration of phased-array elements using phase-shifter modulation and a single scalar detector together with an off-line equation solver. To improve the speed and reduce the complexity of the calibration, this work presents a revised methodology relying only on correlations and eliminating equation solvers within the calibration loop. The new technique, “beamformer calibration using coded correlations” (BC3), operates by calibrating the phased-array's in-phase and quadrature-phase correlations between elements. Within BC3, a first method calibrates the array's response by using two two-dimensional (2-D) correlations. A second method further reduces the total calibration time and improves accuracy by using two one-dimensional (1-D) correlations together with an empirical model to predict gain-dependent phase …

The AERPAW project is an ambitious project, funded by the PAWR program of the US NSF, to create a remote accessible research platform for a research facility with some distinct features that makes its usage model unique, and non-obvious to many researchers desirous of making use of this platform. AERPAW is primarily a physical resource (not a computing or cyber-resource) - the RF enviroment, and the airspace. Experimenters can explore them through radio transceivers and Unmanned Aerial Vehicles, both under the Experimenter’s programmatic control. Since the entire workflow of the user is through the mediation of virtual computing environments, users often tend to think of AERPAW as a computing resource, and find some of the experiment workflow counter-intuitive. In this paper, we articulate the challenges and considerations of designing an experiment workflow that balances the need for …