Sho Muroga

Estimation of Peak Frequency of Loss in Noise Suppressor Using Demagnetizing Factor

This study analyzes the loss peak frequency of an integrated ferromagnetic noise suppressor by evaluating the demagnetizing field. An integrated ferromagnetic noise suppressor is fabricated using a regular silicon process, and relation between the loss peak frequency and demagnetizing field is evaluated. The demagnetizing factor is calculated by approximating the magnetic film by a slender ellipsoid. Measurements of a fabricated on-chip noise suppressor reveal that the loss is maximized at 7 GHz, which is equal to the calculated ferromagnetic resonance (FMR) frequency. Then, the relation between the loss peak frequency and FMR frequency are discussed with some magnetic films in our previous works. The loss peak frequencies in coplanar lines of various magnetic films with different ratios of the film thickness to the signal line width agree well with the FMR frequency of magnetic films. This result reveals that the shift of the loss peak depends on the demagnetizing field over a wide frequency range. Consequently, the loss peak frequency of the integrated ferromagnetic noise suppressor can be controlled as a function of demagnetizing field in the magnetic film.

Performance of Crossed Anisotropy Multilayered CoZrNb Films as IC Chip Level Electromagnetic Noise Suppressor

Co-Zr-Nb multilayers with crossed anisotropy along with multilayers with uniaxial anisotropy were investigated from the standpoint of electromagnetic noise suppressors. Frequency dependences of conduction losses and magnetic near field intensity of a microstrip line (MSL) covered with these multilayers were measured simultaneously. It was found that ferromagnetic resonance excited by RF field from MSL takes a major role of noise suppression over a wide frequency. The ferromagnetic resonance frequency is determined by intrinsic anisotropy field. In addition, shape anisotropy field caused by presence of MSL is negligibly small. The in-plane isotropy feature of noise suppressing performance for the crossed anisotropy films was verified experimentally and numerically.

Ferromagnetic Thin Film Noise Suppressor Integrated to On-Chip Transmission Lines

This paper studies the effects of integrating soft magnetic films to a 0.15 ¿m rule Silicon-On-Insulator (SOI)-CMOS on-chip microstrip line and coplanar line. In microstrip lines, the intensity of ferromagnetic resonance loss increases with increase in the distance between the magnetic film and ground plane because the magnetic fields from the signal and ground lines are mutually opposite; also, the counter field from the ground current becomes weaker according to distance of the ground plane from the magnetic film. For that reason, it is good to locate the signal line close to the magnetic film and the ground line far away. Furthermore, greater loss occurs with a coplanar line than with microstrip line because both the signal and ground line currents contribute to loss generation.

Analysis of Magnetic Flux Through Magnetic Film With Negative Permeability

This paper clarified that a magnetic film becomes transparent for the magnetic flux when the relative permeability of the magnetic film becomes negative above the intrinsic ferromagnetic resonance frequency. We evaluated the magnetic flux through the magnetic film based on magnetic circuit considering leakage magnetic flux from the magnetic film and demonstrated by the near field measurement using shielded loop coil type magnetic field probe. In this case, we used the coplanar transmission line and amorphous CoZrNb film as a source of the magnetic field and a magnetic film, respectively. As a result, we clarified that the magnetic flux in the magnetic circuit increases when the total reluctance of the magnetic film and leakage magnetic flux path decreases because of a negative reluctance of magnetic film. Thus, the magnetic flux through the magnetic film increases only around this frequency. And the magnetic film behaves as a bandpass filter.

Evaluation of Thin Film Noise Suppressor Applied to Noise Emulator Chip Implemented in 65 nm CMOS Technology

This paper reports the shielding effect of soft magnetic film as a thin film noise suppressor applied to a test chip implemented in 65 nm seven metal CMOS technology. This test chip is equipped with a noise generator circuit. The 0.2-1- μm-thick magnetic films, which are integrated with polyimide substrates, are mounted onto the noise generator circuit in the test chip, and 2-μm-thick magnetic film is directly integrated to the passivation of the test chip. These films are deposited by RF magnetron spattering. The shield effect is evaluated by magnetic near-field measurement using planar shielded loop probe and 3-D full-wave electromagnetic field simulation. As a result, we successfully demonstrate a shield effect of 7.7 dB at a crock frequency of 200 MHz with 2-μ m-thick CoZrNb film. Furthermore, the result of the thickness dependence of the shielding effect revealed that a permeability-thickness product (μr × tm) of 1 950 μ m is required as the design target for obtaining 10 dB suppression.

RF Joule Losses Analysis in Thin Film Noise Suppressor Estimated by 3-D Equivalent Circuit Network

This paper discusses the Joule losses in a thin film noise suppressor based on 3-D equivalent circuit network analysis and 3-D full wave electromagnetic field simulation. The thin film and transmission line is divided into number of elements in a plane perpendicular to surface of thin film. Each element is represented by four resistances in length and width direction and capacitors between conductors. Joule loss is quantitatively calculated as a function of sheet resistance using equivalent circuit network analysis. From this result it is successful by shown the Joule loss in thin film is a function of sheet resistance, not the intrinsic resistivity of the thin film or thickness as previous analyses. It is also shown that the Joule loss in the thin film is determined by the two major factors; the eddy current and conduction current deviated from the signal line in the form of displacement current. This result shows that the proposed equivalent circuits well explain the mechanism of the Joule losses in thin film.

On-chip integrated magnetic thin-film solution to countermeasure digital noise on RF IC

Crossed anisotropy amorphous Co85Zr3Nb12 thin film with total magnetic thickness of 2.0 μm is deposited on to the passivation of a test IC chip to accommodate intra IC chip level digital-to-RF noise suppression and telecommunication performance simultaneously. This technology is applicable to other frequency band in 0.41 to 3 GHz by using Co85-(x+y)Zr3+xNb12+y(x: 0-5.5, y: 0-11.0) film. In-band spurious tone is attenuated by 10 dB and the minimum input power level to meet the 3GPP criteria is improved by 8 dB. Intra electromagnetic coupling analysis from digital to RF circuits within the bandwidth of wireless channels have clarified that the magnetic film suppressed conduction noise in on-chip wires.

3-D Magnetic-Near-Field Scanner for IC Chip-Level Noise Coupling Measurements

We present a 3-D magnetic-near-field scanner and a magnetic-near-field probe with a sensor head consisting of a 60 × 60 μm2 on-chip coil. The 3-D scanner consists of an XY stage that positions the device under test with an accuracy of 10 μm and a Z stage that positions the probe and provides yaw-, pitch-, and roll-angle adjustment. The probe outputs are measured by a spectrum analyzer. Furthermore, we demonstrate and clarify the performance of a 1-μm-thick Co85Zr3Nb12 soft magnetic film as a noise suppressor. The film is integrated into a test element group (TEG) chip for next-generation cell phone handsets. The TEG chip is based on a long-term-evolution class complementary metal-oxide-semiconductor radio-frequency integrated circuit receiver. The CoZrNb film suppresses radiated emission by more than 15 dB. These results demonstrate the expected performance of the scanner and probe and the usefulness of the 1-μm-thick CoZrNb film as a noise suppressor.

Electromagnetic shielding effectiveness of non-magnetic metal coated non-woven fabric noise suppressor

The analysis model of non-woven fabric made of synthetic fibers having different diameters for the non-magnetic noise suppressor is developed and the relationship between the wave impedance of free space is considered. The shielding effectiveness to the plane wave can be calculated using the sheet resistance by regarding the non-woven fabrics as a continuous metal sheet. Therefore, it is shown that the low wave-impedance in the fine fiber layers generates high shielding effectiveness.

Analysis of intra-chip degital noise coupling path in fully LTE compliant RF receiver test chip

Intra-electromagnetic noise coupling paths from RF-digital to RF receiver front end can be either of air, wire conduction, Si substrate or package/board. In this paper air and wire conduction coupling paths analysis is discussed. A miniature magnetic near field probe is applied to scan over the test chip to map magnetic near field at LTE band 1(2.1 GHz range). The map is reviewed to extract those on-chip wires that may transfer noise from digital to RF circuits. The extracted wire traces are compared with CAD drawings to build up the FEM simulation model. Each wire is terminated by particular impedance obtained by circuit simulation. The analysis clarified that the magnetic film suppressed conduction noise in on-chip control wires. Simulated total suppression of 11.5 dB well explains the measured suppression of 10 dB.