Showing papers by "Thomas H. Lee published in 2021"

Hybrid Frequency Domain Simulation Method to Speed-up Analysis of Injection Locked Oscillators

Abstract: This paper presents a hybrid frequency domain method to analyze and efficiently simulate injection locked oscillators (ILOs). We combine the recently developed general theory of injection locking with periodic transfer function (PXF) simulation of impulse sensitivity function (ISF). This hybrid method overcomes the time-consuming transient simulation approach and provides design insights unavailable from PXF simulation only. We apply this method to design a microwave frequency divider and 8-phase inverter-based ring oscillator with multi-phase injection. The phase relation between injected signal and locked oscillator output is studied. A simulation speedup factor of over 1500 times is achieved. Good agreement between the proposed and traditional approach is demonstrated.

Analysis and Design of a Tetrahedral Oscillator

Abstract: Analysis and design of a tetrahedral oscillator is presented. Expressions for the startup condition and oscillation frequency are derived. A phase noise analysis of thermal and flicker noise is carried out, using the impulse sensitivity function theory. The noise contribution of each type of transistor is studied, and the dominant and negligible cyclostationary noise sources are identified. There is good agreement among the theory and Spectre simulation. Design guidelines based on the analysis are provided.

Modeling of Injection Locking in Neurons for Neuromorphic and Biomedical Systems

Abstract: We present an approach to characterizing and modeling spiking neurons based on the theory of the impulse sensitivity function (ISF). The ISF concept, originally developed for the design of electronic oscillators, is applied and extended to neurons. The analysis and design of synchronization, entrainment, and phase locking in neurons is accomplished using ISF theory. A circuit example of a biomimetic silicon leaky-integrate- and-fire neuron with positive feedback is presented, and the neuron's ISF is characterized. The insights gained allow the neuron's injection locking behavior, lock range, and relative phase to be predicted and optimized. Close agreement between theory and simulation is demonstrated.

An Electronically Steerable Millimeter-Wave Reflectarray for Wireless Power Delivery

Abstract: Wirelessly delivering power at millimeter-wave frequencies overcomes fundamental physical limitations on the range of lower frequency power delivery systems subject to size and maximum RF power density constraints. We identify the design of a cost-effective, solid-state system for steering a high-directivity beam as a primary challenge in implementing consumer and industrial millimeter-wave wireless power delivery systems, and present the design and measurements of a large-scale 61.5 GHz electronically reconfigurable reflectarray to address this challenge. A dual-channel, two-bit reflective phase shifter IC implemented in 65 nm CMOS forms the core of this design. The antenna array printed circuit board is implemented with a single RF laminate and the phase shifter ICs comprise only 3.5% of the aperture area, minimizing overall system cost. The demonstration array has 874 reflective elements in an area approximately 8.5 cm in diameter, scans to ±50 degrees from boresight, achieves an aperture efficiency of approximately 8.7%, and consumes only 1.1 mW of DC power.