Lingling Sun

Transfer Function Analysis and Broadband Scalable Model for On-Chip Spiral Inductors

Recent models for on-chip spiral inductors have been extensively examined and compared by transfer function analysis. Through the calculation of the transfer functions for the models, including T-, 1-π, and 2-π models, the pros and cons of equivalent circuit topology of each model are evaluated. It is found that the number of poles provided by a certain topology is a constant, while complex poles are responsible for the broadband fitting capacity of the model. The 2-π model has the most poles and the best broadband fitting capacity, while 1-π and T-models are better solutions considering both accuracy and efficiency. A novel broadband model combining the advantages of the physics-based circuit model and behavioral macro-model is proposed for accurately characterizing RF behaviors of spiral inductors. A number of inductors with various geometries have been fabricated to verify the model. Excellent agreements are obtained between the measured data and calculation from the proposed model up to 40 GHz. This modeling method is also applicable to other passive components such as transmission lines and transformers.

Analysis and Equivalent-Circuit Model for CMOS On-Chip Multiple Coupled Inductors in the Millimeter-Wave Region

A growing number of on-chip inductors have been applied in the millimeter-wave IC design. The coupling effects between them have a negative impact on the performance of the circuit and each on-chip inductor. In this paper, a new equivalent-circuit model and a parameter extraction method for multiple on-chip inductors in the millimeter-wave region are proposed. The impacts of coupling effects on every onchip inductor are comprehensive considered in the proposed parameter extraction method. The characteristics of the multiple on-chip-coupled inductors are analyzed, modeled, and measured. The test structures were fabricated by 0.18-μm and 90-nm CMOS processes. The inductances, quality factors, and S-parameters of the model agree well with the measured performance of on-chip-nested and side-by-side-coupled inductors over a wide frequency range from 10 MHz up to millimeter-wave frequency band.

Effects of coil shapes on wireless power transfer via magnetic resonance coupling

The wireless system with four coil resonators is a popular configuration for mid-range wireless power transfer (WPT) via magnetic resonance coupling. The design parameters of four coils have strong impact on efficiency, bandwidth, and transfer distance of the WPT system. In this work, a comprehensive study on effects of coil shapes is conducted. In particular, helix coils, planar spiral coils, and square helix coils are studied. It is shown that the helix coils offer the best performance (e.g. the highest efficiency, the widest bandwidth, and the longest transfer distance) under optimal load whereas the planar spiral coils exhibit the worst performance among these three types of coils. Nevertheless, the performance of the WPT system with helix coils degrades more rapidly than these with other two types of coils when the distance between the transmitting and receiving coils increases.

A Gain Enhanced Cavity Backed Slot Antenna using High Order Cavity Resonance

A gain enhanced method of substrate integrated waveguide (SIW) cavity backed slot antenna by using a high order cavity resonance has been presented in this paper. When the TE220 resonance is excited in the SIW cavity, a high gain radiation with the gain of 8.1 dBi can be achieved, which is about 2.7 dB higher than that of the previously presented SIW cavity backed slot antenna by using the TE120 or TE210 resonance. This design method can be extended to using the higher order cavity resonances such as TE230, TE330 and TE440 etc. to get a much higher gain radiation. Compared with an antenna array which has the same gain, the proposed antenna has advantages of simple feed network and more compact size.

A Broadband and Equivalent-Circuit Model for Millimeter-Wave On-Chip M:N Six-Port Transformers and Baluns

A new equivalent-circuit model and parameter-extraction method for six-port M:N on-chip transformers and baluns are presented in this paper. All of the elements in the proposed model are extracted directly by S-parameters based on full-wave electromagnetic (EM) simulations. Series branches in the model are used to capture the characteristics of the primary and secondary windings. The shunt impedance networks on the terminals represent the substrate loss. The magnetic coupling effects of windings are denoted by six mutual inductances. The electrical coupling effects are represented by mutual capacitances. In this paper, we have developed a parameter-extraction methodology for mutual inductances of six-port transformers. The proposed model and parameters extraction methodology are verified with a number of six-port transformers with different turn ratio by measurements and full-wave EM simulations. The proposed model shows good agreement with measured data over a wide frequency band.

An Analytical Model for the Forming Process of Conductive-Bridge Resistive-Switching Random-Access Memory

An analytical model for the forming process of conductive-bridge resistive-switching random-access memory is developed. The measurable forming time can be calculated using this model giving the biasing condition and is verified to be correct through comparison with the experimental data. The forming time has been shown to have multiple-slopes in exponential dependence on the applied voltage, in agreement with measurement. The model is based on the identification of three steps in the forming process: 1) metal oxidation at the anode; 2) cation migration toward the cathode; and 3) backward filament growth due to electroplating from the cathode. The accuracy of the model has also been established via numerical simulation.

High-Frequency Analysis of Cu-Carbon Nanotube Composite Through-Silicon Vias

A high-frequency analysis of Cu-carbon nanotube (CNT) composite through-silicon vias (TSVs) is conducted. The electrical modeling of the Cu-CNT composite TSVs is performed, with the effective complex conductivity formulated for accurate characterization of kinetic inductance. It is shown that, after codepositing CNT with Cu, the electrical conductivity of the TSVs can be improved and the influence of kinetic inductance variation can be suppressed in comparison with the CNT TSVs. On the other hand, the Cu-CNT composite TSVs can exhibit little compromise in performance yet much enhanced reliability by comparison to the Cu counterpart. That is, the Cu-CNT composite TSVs can provide a better tradeoff between reliability and performance than the Cu and CNT counterparts.

Process simulation of trench gate and plate and trench drain SOI nLDMOS with TCAD tools

In this paper process simulation of a novel structural Silicon On Insulator(SOI) LDMOS cell with Trench Gate and Field Plate and Trench Drain (TGFPTD) was done in a sequence of advanced SOI CMOS processes with Silvaco TCAD. The simulated results indicate that the proposed TGFPTD SOI LDMOS cell is feasible to be fabricated in advanced SOI CMOS technologies and the vertical channel length of the vertical gate nMOSFET can be reduced to about 130 nm.

On-chip sub-terahertz surface plasmon polariton transmission lines with mode converter in CMOS.

An on-chip low-loss and high conversion efficiency plasmonic waveguide converter is demonstrated at sub-THz in CMOS. By introducing a subwavelength periodic corrugated structure onto the transmission line (T-line) implemented by a top-layer metal, surface plasmon polaritons (SPP) are established to propagate signals with strongly localized surface-wave. To match both impedance and momentum of other on-chip components with TEM-wave propagation, a mode converter structure featured by a smooth bridge between the Ground coplanar waveguide (GCPW) with 50u2009Ω impedance and SPP T-line is proposed. To further reduce area, the converter is ultimately simplified to a gradual increment of groove with smooth gradient. The proposed SPP T-lines with the converter is designed and fabricated in the standard 65u2009nm CMOS process. Both near-field simulation and measurement results show excellent conversion efficiency from quasi-TEM to SPP modes in a broadband frequency range. The converter achieves wideband impedance matching (<−9u2009dB) with excellent transmission efficiency (averagely −1.9u2009dB) from 110u2009GHz–325u2009GHz. The demonstrated compact and wideband SPP T-lines with mode converter have shown great potentials to replace existing waveguides as future on-chip THz interconnects. To the best of the author’s knowledge, this is the first time to demonstrate the (sub)-THz surface mode conversion on-chip in CMOS technology.

A 60-GHz 19.8-mW Current-Reuse Active Phase Shifter With Tunable Current-Splitting Technique in 90-nm CMOS

A 60-GHz 4-bit vector-summing phase shifter has been implemented in a 90-nm CMOS process. Based on a tunable current-splitting technique with π-type low-pass filter (LPF) and T-type high-pass filter (HPF), a quadrature adjustable amplitude generator is developed to improve the insertion loss and adjust quadrature signals amplitudes. Variable gain amplifiers (VGAs) that are widely used in traditional phase shifters are replaced by the generator to reduce power consumption. In addition, a balun-based current-reuse technique is applied to further save dc power. The overall consumed direct current is 11 mA under 1.8-V voltage supply. The measured results show that the phase shifter with an output balun (with loss of 1.6 dB) achieves gain of -0.4~2.5 dB at 60 GHz and root mean square (rms) gain error is 0.75~1.6 dB in the frequency regime from 57 to 64 GHz. The peak average gain is 1.1 dB at 59.7 GHz. By employing a calibration method, the measured rms phase error ranges from 2.3° to 7.6° from 57 to 64 GHz. The tested 60-GHz input 1-dB compression point (P1dB) and noise figure (NF) for 16 phase states are -9.8 ± 0.8 dBm and 11 ± 1.3 dB, respectively.