Jing Zhan

Investigation of On-Chip Soft-Ferrite-Integrated Inductors for RF ICs—Part II: Experiments

We report the systematic study and design optimization of CMOS-compatible on-chip ferrite-integrated inductors, including detailed quantitative analysis by simulation and circuit modeling, new ferrite fabrication and characterization, ferrite-integrated-inductor design, measurement, and optimization. A new ferrite nanopowder-mixed-photoresist spin-coating/inkjetting technique is discussed. The design and characterization of ferrite-integrated inductors with various ferrite-filling structures are presented. Measurement shows substantial improvement of up to +160% in inductance (L) and + 220% in quality factor (Q) across the multigigahertz frequency spectrum with a self-resonance frequency (f 0) over 20 GHz for the new ferrite-integrated inductors. This study clearly suggests that the new ferrite-integrated inductor technique is a potential solution to the realization of radio-frequency systems-on-a-chip requiring high-performance compact on-chip inductors. This work is presented in two parts. Part I discusses the design and simulation of ferrite-integrated inductors. This paper is Part II, presenting experimental results for material research and device implementation.

Design and Analysis of Vertical Nanoparticles-Magnetic-Cored Inductors for RF ICs

We report the design and analysis of the first vertical magnetic-cored inductors in CMOS backend for radio-frequency (RF) ICs, which includes theoretical and experimental studies of device architecture, equivalent circuit model with parameter extraction technique, process development, and device characterization. Vertical magnetic cores with multiple-layer stacked-spiral structures are designed to realize compact inductive devices in RF ICs. A CMOS-compatible post-CMOS backend process module (CMOS +) and optimized high-permeability nanoparticles are utilized to achieve a high inductance-to-coil-area ratio (L-density) in gigahertz range. The prototype six-layer inductors with NiZnCu ferrite nanoparticles-magnetic-core were fabricated in a commercial foundry 0.18-μm six-metal RF CMOS technology. A high L-density of over 700 nH/mm2 to multigigahertz was obtained, with an 80% chip size reduction from the reference planar magnetic inductors. An equivalent circuit model with parameter extraction technique is developed to analyze magnetic enhancement effects. This work demonstrates the potential of design and integration of compact high-performance vertical magnetic-cored inductive devices into CMOS backend for high-quality and low-cost RF systems-on-a-chip.

Investigation of On-Chip Soft-Ferrite-Integrated Inductors for RF ICs—Part I: Design and Simulation

We report a systematic investigation and design optimization of CMOS-compatible on-chip ferrite-integrated inductors, including a detailed quantitative analysis by simulation and circuit modeling, new ferrite material fabrication and characterization, and ferrite-integrated-inductor design, characterization, and optimization. A new ferrite nanopowder-mixed-photoresist spin-coating/inkjetting technique is discussed. The design and characterization of ferrite-integrated inductors with various ferrite-filling structures are presented. Measurement shows substantial improvement of up to +160% in inductance (L) and + 220% in quality factor (Q) across the multigigahertz frequency spectrum with a self-resonance frequency (f 0) of over 20 GHz for the new ferrite-integrated inductors. This paper clearly suggests that the new ferrite-integrated-inductor technique is a potentially viable solution to the realization of radio-frequency systems-on-a-chip requiring high-performance compact on-chip inductors. This work is presented in two parts. This paper is Part I, discussing the design and simulation of ferrite-integrated inductors. Part II discusses the experimental work, including material research and device implementation.

Application of ferrite nanomaterial in RF on-chip inductors

Several kinds of ferrite-integrated on-chip inductors are presented. Ferrite nanomaterial applied in RF on-chip inductors is prepared and analyzed to show the properties of high permeability, high ferromagnetic resonance frequency, high resistivity, and low loss, which has the potential that will improve the performance of RF on-chip inductors. Simulations of different coil and ferrite nanomaterial parameters, inductor structures, and surrounding structures are also conducted to achieve the trend of gains of inductance and quality factor of on-chip inductors. By integrating the prepared ferrite magnetic nanomaterial to the on-chip inductors with different structures, the measurement performances show an obvious improvement even in GHz frequency range. In addition, the studies of CMOS compatible process to integrate the nanomaterial promote the widespread application of magnetic nanomaterial in RF on-chip inductors.

Stacked-Spiral RF Inductor With Vertical Nano-Powder Magnetic Core in CMOS

This letter reports a novel concept of vertical stacked-spiral RF inductor with integrated nano-powder-magnetic-core in standard CMOS. A proof-of-concept design in a foundry 0.18 6-metal CMOS using a new post-CMOS backend process (CMOS+) is depicted. Measurement shows significant improvement in inductance of 35% and quality factor of 41% up to multi-GHz in prototype. An -density of 420 at 1.2 GHz is achieved. Limiting factors for the relatively low factor in the prototypes and improvement method are discussed.

Surface acoustic wave characteristics based on c-axis (006) LiNbO3/diamond/silicon layered structure

The characteristics of surface acoustic wave (SAW) based on LiNbO3/diamond/silicon layered structure were investigated. The LiNbO3 film deposited on the diamond/silicon substrate by pulsed laser deposition exhibits highly c-axis (006) preferred orientation. Four samples with different wavelengths were fabricated on the same substrate to study the normalized LiNbO3 thickness dependence of SAW properties. It is shown that the measured phase velocities are in good agreement with the theoretical ones. In the case of 1st wave mode, the SAW device with a linewidth of 1.78 µm exhibits a very high phase velocity of 12 474 m/s in conjunction with a high electromechanical coupling coefficient of 4.85%.

A 2.7-mW 1.36–1.86-GHz LC-VCO With a FOM of 202 dBc/Hz Enabled by a 26%-Size-Reduced Nano-Particle-Magnetic-Enhanced Inductor

This paper reports the first LC voltage-controlled oscillator (LC-VCO) in CMOS utilizing a novel nontraditional compact inductor with integrated vertical nano particles magnetic core (Ni-Zn-Cu) to improve the figure-of-merit (FOM) of the VCO circuit. The new magnetic-enhanced inductor, fabricated in an integrated-circuit back-end using a CMOS-compatible process, improves inductance density ( L-density) and quality factor ( Q-factor) up to 7 GHz. A 1.36-1.86-GHz VCO with a nano-ferrite-integrated inductor was fabricated in a 180-nm RF CMOS. Measurements show that the magnetic-cored inductor improves the L-density and Q-factor by 49.8% and 59.2% at 1.8 GHz, respectively, while reducing the size by 26%. The VCO achieves reduced power consumption of 2.7 mW at a 1.8-V supply, low phase noise of less than -121, and -126 dBc/Hz at 100-kHz and 1-MHz frequencies offset, and a high FOM of 202 dBc/Hz. This prototype VCO demonstrates that the new vertical-nano-magnetic-cored inductor technology is a potential solution to high-performance low-cost compact RF systems-on-chip.

On-chip soft-ferrite-integrated inductors for RF IC

Systematic investigation of novel CMOS-compatible on-chip ferrite-integrated RF inductors is reported. New ferrite-fully-filled solenoid inductor is achieved, using low-temperature ferrite nano-powder-mixed-photoresist inkjetting/spin-coating technique we developed, which shows significant improvement of +160% in L and +220% in Q, to multi-GHz. An improved equivalent circuit for new ferrite-integrated inductors is developed. This work shows excellent prospects for making compact high-quality on-chip soft-ferrite-integrated inductors for RF SoCs.

Stacked-spiral RF inductors with vertical nano-particle-magnetic-medium

A new concept of stacked-spiral inductor with vertical near-closed-circuit nano-particle-magnetic-core in CMOS is reported. Prototypes, fabricated in a 6-Al-metal CMOS backend process using ferrite nano-particles, show a high inductance-density of 825nH/mm2 in multi-GHz, which is promising for making super compact inductors in RF SoC.

Design of magnetic RF inductor in CMOS

Traditional planar inductors in Radio Frequency (RF) Integrated Circuits (ICs) are plagued by large areas, low quality, and low frequencies. This paper describes a magnetic-based CMOS-compatible RF inductor. Magnetic-core inductors with various ferrite-filled structures, spiral structures, and magnetic material permeabilities were simulated to show that this inductor greatly improves the inductance by up to 97% and quality factor by 18.6% over a multi-GHz frequency range. The results indicate that the inductor is a very promising and viable solution to realize miniature, high quality, and high frequency on-chip inductors for high-end RF ICs.