A 12MHz Switched-Capacitor Relaxation Oscillator with a Nearly Minimal FoM of -161dBc/Hz

In this work the phase noise performance of relaxation oscillators has been analyzed resulting in simple though precise phase noise expressions. These expressions have lead to a new relaxation oscillator topology, which exploits a noise filtering technique implemented with a switched-capacitor circuit to minimize phase noise. Measurements on a 65nm CMOS design show a sawtooth waveform, a frequency tuning range between 1 and 12MHz and a rather constant frequency tuning gain. At 12MHz oscillation frequency it consumes 90μW while the phase noise is -109dBc/Hz at 100KHz offset frequency. By minimizing and balancing noise contributions of charge and discharge mechanisms, a nearly minimal FoM of -161dBc/Hz has been achieved, which is a 6dB improvement over state-of-the-art

On numerical methods for highly oscillatory problems in circuit simulation

We propose in this paper a novel technique for an efficient numerical approximation of systems of highly oscillatory ordinary differential equations. In particular, we consider electronic systems subject to modulated signals. A Filon-type method is proposed for use and compared with traditional trapezoidal rule and Runge–Kutta methods. The Filontype method is combined with the waveform relaxation technique for nonlinear systems. Preliminary numerical examples highlight the efficacy of this approach

A 90μW 12MHz Relaxation Oscillator with a -162dB FOM

A relaxation oscillator exploits a noise filtering technique implemented with a switched-capacitor circuit to minimize phase noise. A 65nm CMOS design produces a sawtooth waveform, has a frequency tuning range of 1 to 12MHz and a constant frequency-tuning gain. By minimizing and balancing noise contributions from charge and discharge mechanisms, a FOM of -162dB is achieved, which is a 7dB improvement over state-of-the-art

Compressed Passive Macromodeling

This paper presents an approach for the extraction of passive macromodels of large-scale interconnects from their frequency-domain scattering responses. Here, large scale is intended both in terms of number of electrical ports and required dynamic model order. For such structures, standard approaches based on rational approximation via vector fitting and passivity enforcement via model perturbation may fail because of excessive computational requirements, both in terms of memory size and runtime. Our approach addresses this complexity by first reducing the redundancy in the raw scattering responses through a projection and approximation process based on a truncated singular value decomposition. Then we formulate a compressed rational fitting and passivity enforcement framework which is able to obtain speedup factors up to 2 and 3 orders of magnitude with respect to standard approaches, with full control over the approximation errors. Numerical results on a large set of benchmark cases demonstrate the effectiveness of the proposed techniqu

An efficient algorithm for the parallel solution of high-dimensional differential equations

The study of high-dimensional differential equations is challenging and difficult due to the analytical and computational intractability. Here, we improve the speed of waveform relaxation (WR), a method to simulate high-dimensional differential-algebraic equations. This new method termed adaptive waveform relaxation (AWR) is tested on a communication network example. Further we propose different heuristics for computing graph partitions tailored to adaptive waveform relaxation. We find that AWR coupled with appropriate graph partitioning methods provides a speedup by a factor between 3 and 16

Reduced Order Modelling for the Simulation of Quenches in Superconducting Magnets

This contributions discusses the simulation of magnetothermal effects in superconducting magnets as used in particle accelerators. An iterative coupling scheme using reduced order models between a magnetothermal partial differential model and an electrical lumped-element circuit is demonstrated. The multiphysics, multirate and multiscale problem requires a consistent formulation and framework to tackle the challenging transient effects occurring at both system and device level

Augmented Models of High-Frequency Transformers for SMPS

The modeling of high-frequency transformers via augmented equivalent circuits is addressed. The augmented models are composed of a low-frequency equivalent and a supplemental element modeled via real rational fitting. They offer both high accuracy levels and a physical meaning that helps the interpretation of simulation results. Parasitics effects between the windings and between the windings and the carrying board can be also included. The use of an augmented model for the simulation of a dc-dc converter is demonstrate

Custom Integrated Circuits

Contains reports on seven research projects.U.S. Air Force - Office of Scientific Research (Contract F49620-84-C-0004)National Science Foundation (Grant ECS81-18160)Defense Advanced Research Projects Agency (Contract NOO14-80-C-0622)National Science Foundation (Grant ECS83-10941