On-chip micromachined solenoid balun for RF-SOC applications

A transformer balun is fabricated by using a post-CMOS compatible MEMS process. The novel concave-suspended solenoid balun can be integrated with radio-frequency system-on-chips (RF-SOCs). In the frequency range 0.5-10 GHz, the tested balun shows less than 0.7 dB amplitude imbalance and less than 1.5deg phase imbalance. After tuning, the transformer balun can match between a 100 Omega single-ended port and two 50 Omega differential ports. At the two differential ports, insertion losses of -1.5 and -0.8 dB are obtained at 5-GHz centre frequency, more than 40% bandwidth of S ₁₁ is achieved.     

Modeling and analysis of 3-D solenoid embedded inductors

Investigation of the statistical variation of integrated passive components is crucial for designing and characterizing the performance of multichip module (MCM) substrates. In this paper, the statistical analysis of three-dimensional (3-D) solenoid inductors manufactured in a multilayer low-temperature cofired ceramic (LTCC) process is presented. A set of integrated inductor structures is fabricated, and their scattering parameters are measured for a range of frequencies from 50 MHz to 5 GHz. Using optimized equivalent circuits obtained from HSPICE, mean and absolute deviation is calculated for each component of each device model. Monte Carlo Analysis for the inductor structures is then performed using HSPICE. Using a comparison of the Monte Carlo results and measured data, it is determined that for even a small number of sample structures, the statistical variation of the component values provides an accurate representation of the overall inductor performance     

A 22-GHz push-push CMOS oscillator using micromachined inductors

This letter presents a low phase noise 0.35-/spl mu/m CMOS push-push oscillator utilizing micromachined inductors. This oscillator results in an improvement in phase noise compared with the previously published Si-based voltage-controlled oscillators (VCOs) around 20GHz. With the high-Q inductors introduced by the micromachined structure, the oscillator achieves an oscillating frequency of 22.2GHz while exhibiting an output power of -7.5dBm with a phase noise of -110.1dBc/Hz at 1-MHz offset. This work also demonstrates the highest operating frequency among previously published Si-based VCOs using micromachined structures.     

Fabrication and performance of a micromachined 3-D solenoid inductor

A high-Q and f_res (self-resonant frequency)solenoid inductor was fabricated by using the microelectromechanical systems(MEMS) technology with air-core structure. This inductor has an air core and an electroplated copper coil to reduce the series resistance, and the solenoid structure with laterally laid out structure saves the chip area significantly. The measurement results show that this inductor has high Q-factor and stable inductance over wide range of operating frequency. The maximum Q-factor of this inductor is 38 and the inductance is 1.78 nH at 5 GHz with an air core of 45 μm. Moreover, the Q-factor and the inductance grow with the increasing of the air core.     

CMOS-compatible micromachined edge-suspended spiral inductors with high Q-factors and self-resonance frequencies

This paper reports a new category of high-Q edge-suspended inductors (ESI) that are fabricated using CMOS-compatible micromachining techniques. This structure was designed based on the concept that the current was crowded at the edges of the conducting metal wires at high frequencies due to the proximity effect. The substrate coupling and loss can be effectively suppressed by removing the silicon around and underneath the edges of the signal lines. Different from the conventional air-suspended inductors that have the inductors built on membranes or totally suspended in the air, the edge-suspended structures have the silicon underneath the center of the metal lines as the strong mechanical supports. The ESIs are fabricated using a combination of deep dry etching and anisotropic wet etching techniques that are compatible with CMOS process. For a three-turn 4.5-nH inductor, a 70% increase (from 6.8 to 11.7) in maximum Q-factor and a 57% increase (from 9.1 to 14.3 GHz) in self-resonance frequency were obtained with a 11-/spl mu/m suspended edge in 25-/spl mu/m-wide lines.     

On-chip embedded toroidal solenoid inductors and transformers formed by post-CMOS micromachining techniques

This paper presents a micromachined implementation of embedded toroidal solenoids for high-performance on-chip inductors and transformers, which is highly demanded in radio-frequency integrated circuits (RFICs). Microfabricated on CMOS compatible silicon wafers with post-CMOS micromachining techniques, the RF toroidal components can constrain the magnetic flux into a well-defined path and away from other on-chip RF devices, thereby, being in favor of decrease in RF loss, increase in Q-factor and elimination of electromagnetic interference. By using a technical combination of an anisotropic wet etch and an isotropic dry etc., the micromachined toroidal structure can be used for the formation of metal solenoid by copper electroplating. Processed under low temperature (Max 120 °C for photoresist hard-baking), the three mask microfabrication can be compatible with CMOS IC fabrication in a post-process way. The formed toroidal inductors with 4.92 nH and 8.48 nH inductance are tested, and we obtain maximum Q-factors of 25.7 and 17.8 at 3.6 GHz and 3.1 GHz, while the self-resonant frequencies are 17.3 GHz and 7.4 GHz, respectively. On the other hand, two types of toroidal transformers are also formed and tested, resulting in satisfactory RF-performance. Therefore, the novel techniques for close-loop solenoid inductors are promising for high-performance RF ICs.     

Surface micromachined accelerometers

Surface micromachining has enabled the cofabrication of thin-film micromechanical structures and CMOS or bipolar/MOS integrated circuits. Using linear, single-axis accelerometers as a motivating example, this paper discusses the fundamental mechanical as well as the electronic noise floors for representative capacitive position-sensing interface circuits. Operation in vacuum lowers the Brownian noise of a polysilicon accelerometer to below 1 μg/√(Hz). For improved sensor performance, the position of the microstructure should be controlled using electrostatic force-feedback. Both analog and digital closed-loop accelerometers are described and contrasted, with the latter using high-frequency voltage pulses to apply force quanta to the microstructure and achieve a very linear response     

On-chip solenoid inductors with high quality factor for high frequency magnetic integrated circuits

On-chip solenoid inductors for high frequency magnetic integrated circuits are proposed. The eddy current loss was reduced by dividing the inductor into three consecutive inductors connected in series. The inductor has an inductance of 1.1nH and the maximum quality factor (Q/sub max/) of 50.5. The self-resonant frequency and the operating frequency at Q/sub max/ are greater than 17.5GHz and 16.7GHz, respectively.     

Surface micromachined RF MEMS variable capacitor

We used simple microelectromechanical systems (MEMS) technology to fabricate low-voltage-controlled variable capacitors with high-quality factor. The surface profile of the variable capacitor at different values of applied voltage is measured using WYKO NT1100 optical surface profiler. The pull-in voltage of the variable capacitor was below 15 V. The capacitance and quality factor at 1 GHz are 0.792 and 51.6 pF. The pull-in voltage is 13.5 V, the tuning ratio of the capacitor is more than 1.31:1.     

Broadband on-glass antenna with mesh-grid structure for automobiles

A broadband on-glass antenna for automobiles based on a mesh structure is designed for operation in the VHF and UHF bands. A genetic algorithm is used to optimise the mesh-grid structure of the antenna for good impedance matching. The optimised antenna operates similarly to a loop antenna and is well matched to a system impedance of 250 /spl Omega/. The results of simulation and measurement on a prototype antenna on a ground plane show an average VSWR of 1.67 and 1.70, respectively, over the frequency bands of interest.     

A comparison of two micromachined inductors (bar- and meander-type)for fully integrated boost DC/DC power converters

Two micromachined integrated inductors (bar- and meander-type) are realized on a silicon wafer by using modified, IC-compatible, multilevel metallization techniques. Efforts are made to minimize both the coil resistance and the magnetic reluctance by using thick electroplated conductors, cores, and vias. In the bar-type inductor, a 25-μm thick nickel-iron permalloy magnetic core bar is wrapped with 30-μm thick multilevel copper conductor lines. For an inductor size of 4 mm×1.0 mm×110 μm thickness having 33 turns of multilevel coils, the achieved specific inductance is approximately 30 nH/mm² at 1 MHz. In the meander-type inductor, the roles of conductor wire and magnetic core are switched, i.e., a magnetic core is wrapped around a conductor wire. This inductor size is 4 mm×1.0 mm×130 μm and consists of 30 turns of a 35-μm thick nickel-iron permalloy magnetic core around a 10-μm thick sputtered aluminum conductor lines. A specific inductance of 35 nH/mm² is achieved at a frequency of 1 MHz. Using these two inductors, switched DC/DC boost converters are demonstrated in a hybrid fashion. The obtained maximum output voltage is approximately double an input voltage of 3 V at switching frequencies of 300 kHz and a duty cycle of 50% for both inductors, demonstrating the usefulness of these integrated planar inductors     

Surface micromachined integrated optic polarization beam splitter

An integrated polarization beam splitting system composed of one binary phase Fresnel collimating lens and one polarization beam splitter (PBS) has been realized on a single Si chip using a commercially available foundry polysilicon surface micromachining process [Multi-User Mems Process, or (MUMPS)] at Mems Center at North Carolina (MCNC). The polarization extinction ratios of 10 dB for the transmitted light and over 20 dB for the reflected light have been achieved. The whole system is prealigned through computer-aided design on a Si substrate and is lifted up perpendicular to the substrate after structure release. This system opens opportunities for various applications where the light polarization states could be utilized     

Linearity and low-noise performance of SOI MOSFETs for RFapplications

The MOSFET parameters important for RF application at GHz frequencies: a) transition frequency, b) noise figure, and c) linearity are analyzed and correlated with substrate type. This work demonstrates that, without process changes, high-resistivity silicon-on-insulator (high-ρ SOI) substrates can successfully enhance the RF performance of on-chip inductors and fully depleted (FD)-SOI devices in terms of reducing substrate losses and parasitics. The linearity limitations of the SOI low-breakdown voltage and "kink" effect are addressed by judicious device and circuit design. Criteria for device optimization are derived. A NF = 1.7 dB at 2.5 GHz for a 0.25 μm FD-SOI low-noise amplifier (LNA) on high-ρ SOI substrate obtained the lowest noise figure for applications in the L and S-bands     

High-performance implanted base silicon bipolar technology for RFapplications

A 0.4 μm silicon bipolar technology for mixed digital/analog RF-applications is described. Without increasing the process complexity in comparison to current production technologies transit frequencies of 52 GHz, maximum oscillation frequencies of 65 GHz and minimum noise figures of 0.7 and 1.3 dB at 3 and 6 GHz are achieved. Emitter-coupled logic (ECL) ring oscillators have a minimum gate delay of 12 ps, the low power capability of the technology is proven by a current-mode logic (CML) power delay product of 5.2 fJ and a dynamic frequency divider operates up to 52 GHz. These results demonstrate the suitability of this technology for mobile communications up to at least 6 GHz and for high-speed optical data links at 10 Gbit/s and above     

Noise modeling and SiGe profile design tradeoffs for RFapplications [HBTs]

This paper investigates SiGe profile design tradeoffs for low-noise RF applications at a given technology generation (i.e., fixed minimum feature size and thermal cycle). An intuitive model relating structural parameters and biases to noise parameters is used to identify the noise limiting factors in a given technology. The noise performance can be improved by pushing more Ge into the base and creating a larger Ge gradient in the base. To maintain the SiGe film stability, the retrograding of the Ge into the collector has to be reduced, leading to a stronger f_T-I_C roll-off at high injection. Two low-noise profiles were designed and fabricated explicitly for improving minimum noise figure (NF_min) without sacrificing gain, linearity, frequency response, or the stability of the SiGe strained layer. A 0.2 dB NF_min was achieved at 2.0 GHz with an associated gain (G_assoc) of 13 dB     

变压器和电感器

可承载40A的自屏蔽SMT电感器 HM73系列钼铁镍合金粉末自屏蔽SMT电感器从0.1～8.2μH有16种额定值,最高可承受40A和400μJ/cm~3。它们是用导体密度比圆形导线高20％的超薄矩形导线制造的,它们还具有0.08～15.2mΩ的DCR。     

Negative inductors and capacitors for SPICE simulation

It is explained that to simulate circuits containing negative inductances and capacitances using general-purpose simulators like SPICE, the networks under consideration must be transformed into suitable SPICE-compatible circuits. Criteria that the portion of the network containing the negative elements should meet are given. The SPICE network realizing these elements, when L and C are independent of frequency and time, is shown. An example of a Brune network is given     

Active inductors for GaAs and bipolar technologies

Integrated high performance gallium arsenide and silicon active inductor configurations for microwave frequencies are examined in this article. The existing topologies are considered and a new aspect of comparing the performance of different topologies based on a more complete analysis is utilised. Drawbacks of GaAs technology in this particular case are recognised, while benefits attained by using bipolar technology are presented. A theoretical basis for designing bipolar inductors is examined. On the basis of these studies a new method for raising the Q-factor of an active inductor is found and applied to two novel GaAs Q-enhanced active inductors. New applications for active high-Q resonators are found and their realisation aspects are considered. Integrated test circuits have been designed, and the simulated and experimental results are presented.     

Integrated solenoid inductors with patterned, sputter-deposited Cr/Fe/sub 10/Co/sub 90//Cr ferromagnetic cores

Ferromagnetic (FM) films suitable for implementation in between interconnect layers of a standard CMOS fabrication process are demonstrated to yield considerable size reduction of monolithic radio frequency (RF) inductors, leading to lower cost. The deposition of a FM Cr(5 nm)/Fe/sub 10/Co/sub 90/(500 nm)/Cr(15 nm) stack is performed by magnetron sputtering at room temperature under a dc magnetic field of /spl sim/ 10 mT along the magnetic easy-axis. A lift-off technique, using a four-layer shadow mask, is used for pattern transfer to the magnetic stack to circumvent apparent difficulties in the patterning of FM films. A series of solenoid-type inductors with FM cores are demonstrated and compared to control devices with air cores. A more than eight-fold enhancement of the inductance and a seven-fold improvement of the quality factor are achieved.     

Thin-film superconducting inductors for power electronics

Superconducting thin-film inductors promise to be key elements in high-frequency, high-power density, high-efficiency power supplies. A thin-film (0.6 μm-thick) YB₂Cu₃O₇ inductor capable of handling currents up to 12 A DC was found to have a Q value of 1300 at 260 MHz and 77 K, a factor of 20 higher than an identical inductor made of 15 μm thick Cu; this improvement factor is shown to be >64 at lower frequencies (a few MHz)