Monolithic on-chip inductors are key passive devices in radio frequency integrated circuits (RFICs). Currently, 70–80% of the on-wafer area of most RFIC chips is occupied by the sprawling planar spiral inductors, and its operation frequency is limited to a few GHz. With continuous scaling of the transistor technology, miniaturization and high frequency operation of inductors have become the bottleneck to meet future demands of wireless communication systems. Here we report on-chip self-rolled-up 3D microtube inductors with extremely small footprint, unprecedented high frequency performance and weak dependence on substrate conductivity. The serpentine metal strips are deposited on an oppositely strained silicon nitrides (SiNx) bilayer. After releasing from the sacrificial layer underneath, the metal/SiNx layer is scrolled into a 3D hollow tubular structure by the strain induced unidirectional self-rolled-up technology. Compared to the planar spiral inductors with similar inductances and quality (Q) factors, the footprint of tube inductors is reduced by as much as two orders of magnitude, and the frequency at peak Q factor improves more than 5 times on doped substrates. The self-rolled-up 3D nanotechnology platform employed here, that “processes in 2D but functions in 3D”, is positioned to serve as a global solution for extreme RFIC miniaturization with improved performance.
This paper presents results on the development and application of a three-dimensional (3-D) microstructure assembly technique-Plastic deformation magnetic assembly (PDMA). In PDMA, certain part of the microstructure to be assembled is plastically deformed by the magnetic force generated from the interaction between a magnetic material piece deposited on the microstructure and an external magnetic field. As a result, the entire microstructure can remain at a rest angle with respect to the substrate surface due to the plastic deformation. The amount of plastic deformation and the rest angle are found to be strongly dependent on the properties and the geometric parameters of the deformation region of the microstructure and also the magnetic material piece. A general design rule for PDMA has been given. PDMA is capable of batch-scale assembly. It has been successfully applied to fabricate novel micromachined devices with high yield and good controllability. As an example, the results of a novel vertical planar spiral inductor realized by the application of PDMA have also been presented in the paper.
A" .• /rac/-This work presents a new approach for the time-domain simulation of transients on a dispersive and loss)' transmission line tenninated with active devices. The method combines the scattering matrix of an arbitrary line and the nonlinear causal impedance functions at the loads to derive expressions for the signals at the near and far ends. The problems of line losses, dispersion, and nonlinearities are first investigated. A time-domain formulation is then proposed using the scatter• ing matrix representation. The algorithm assumes that dispersion and loss models for the transmission lines are available and that the frequency dependence is known. Large-signal equivalent circuits for the terminations are assumed to be given. Experimental and computer•simulated results are compared for the Iossless dispersionless case, and the effects of losses and dispersion are predicted.
In this work, a finite difference formulation is used to simulate large networks. The method makes use or introduces reactive latency in all branches and nodes of a circuit to generate update algorithms for the voltage and current quantities. A criterion is established that guarantees the stability of the algorithm for specified choices of the time step. Because of its linear numerical complexity, several orders of magnitude in speedup over matrix-based methods are obtained. Nonlinear networks can also be simulated by the formulation. Several comparisons are made with standard simulators in order to evaluate the accuracy and efficiency of the algorithm. In all cases that satisfy the stability criterion, good agreements with established techniques are obtained.
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