Mizuki Iwanami

Ultra small electro-optic field probe fabricated by aerosol deposition

We developed a microscopic electro-optic field probe by directly depositing a lead zirconate-titanate [PbZr0.3Ti0.7O3] film onto the optical fiber edge using aerosol deposition. Its fabrication process is low-cost and relatively easy because there are no complicated procedures such as fine lithography and etching. The lateral size of the film is 125µm, which is the same as the diameter of a typical single mode fiber, and the thickness is approximately 5µm. An RF electro-optic signal was successfully measured over a microstrip line. The capability for detecting GHz range fields is also shown. Because it is very tiny and thin, the developed electro-optic probe has great potential for detailed electrical characterization in the microscopic regions of high performance electronic products such as the interconnecting parts between LSI packages and printed circuit boards and spaces among different LSI chips in a package.

Magnetic near-field measurements over LSI package pins by fiber-edge magnetooptic probe

To establish a method for investigating hidden radiation sources and their mechanisms in a printed circuit board, we performed preliminary measurements of one-dimensional magnetic near-field distribution over pins of a large-scale integrated circuit (LSI) package by means of an optical method: the fiber-edge magnetooptic (FEMO) probing technique. The FEMO probe consists of fiber optics and a magnetooptic crystal glued at a fiber edge. Its planar spatial resolution is approximately 100 /spl mu/m. It was found that a magnetic field generated from each LSI pin could be distinguished and some radiation was generated from ground and power supply lines. We compared the measured results with corresponding radiated electric field strength that was separately measured. The frequency of interest was the tenth harmonic of the output signal. We observed a strong correlation between those two experimental results, which suggests the effectiveness of our proposed method for near-field investigation. One of the beneficial features of the FEMO probe is its small probe head, due to which one can perform detailed near-field evaluations in a microscopic region. Furthermore, we tried to specify a major electromagnetic interference source by additional measurements of near-field distributions and frequency dependence of magnetooptic signals. It was suggested that the short-through current flowing in the power-supply system of the input/output circuits caused high-level radiated emission.

Wideband Magnetooptic Probe with 10 µm-Class Spatial Resolution

In this paper we give the results of the trial fabrication and basic performance evaluation of the fiber-edge magnetooptic (FEMO) probe with an approximately 10-µm-thick magnetooptic (MO) crystal. It utilizes the Faraday effect during rotational magnetization in a MO crystal for magnetic field sensing. One should note that as compared to a previously reported FEMO probe, the spatial resolution was improved keeping the similar measurable bandwidth. The developed probe had a 10-µm-class spatial resolution as well as a measurable bandwidth of approximately 2.5 GHz. Furthermore, the realization of this probe made it possible to perform GHz-range magnetic near-field mappings over a fine meander circuit, which means that one can visualize fine current distributions in this frequency range. We compared the measured magnetic field maps with the simulated ones obtained using an electromagnetic field simulator for analyses of GHz-range electromagnetic field distributions. As a result, it was found that sufficiently precise near-field distributions could be measured due to the low invasiveness and superior spatial resolution of the probe.

Study of the crystal size effect on spatial resolution in three-dimensional measurement of fine electromagnetic field distribution by optical probing

The effect of crystal size on the spatial resolution of electro/magneto-optic probing measurement has been studied. This is especially important when one deals with three-dimensional field visualization over fine and complicated circuit patterns. Through experimental three-dimensional field analyses, the concept of the sensitive volume is introduced and has been proved to be an appropriate measure to define the three-dimensional spatial resolution. Based upon the reduction of the sensitive volume of a magneto-optic crystal, a magnetic field distribution over a 10-µm-class miniature circuit was precisely visualized in the x–z plane by the fiber edge magneto-optic probe using a 20-µm-thick crystal.

Investigation of electromagnetic noise coupling that affects packet error rates in wireless-LAN mounted printed circuit boards

This paper shows experimental results of packet error rates (PERs) in wireless-LAN mounted printed circuit boards and gives a discussion on a channel of electromagnetic noise coupling that affects the PER. We utilize the amplitude probability distribution (APD), a statistical and quantitative method for noise evaluation, to investigate the noise coupling channel. Evaluation results indicate that the noise transmitting space and coupling to an antenna cause an increase of the PER.

Suppression of conducted noise coupling in a board with digital and RF circuits by a ferrite film plated on an interposer

This paper presents evaluation results of conducted noise suppression effect of a ferrite film directly plated on an interposer substrate in the long-term evolution (LTE) communication band. A test board for evaluations has an IC with digital and RF circuits which is designed for investigations of electromagnetic noise coupling at the IC chip level. Firstly, we have confirmed effectiveness of a ferrite film onto an interposer in suppression of conducted noise from a digital circuit to a board by simulations. Then, we have verified that the ferrite film reduces conducted noise coupling to the RF circuit, occurring inside the board, by measurements of In-phase/Quadrature (I/Q) signals and high frequency voltages of power supply lines.

Ultra Small Fiber-Optic Electric Field Probe Fabricated by Aerosol Deposition

We developed a microscopic electro-optic field probe by directly depositing a lead zirconate-titanate [PbZr0.3Ti0.7O3] film onto optical fiber edge using aerosol deposition. Its fabrication process is virtually self-aligning because there are no complicated procedures such as fine lithography and etching. The lateral size of the film pattern is 125 mum, which is the same as the diameter of a typical single mode fiber, and the thickness is approximately 5 mum. An RF electro-optic signal was successfully measured over a microstrip line. The measurable bandwidth of the probe was over 2 GHz. Because it is very tiny and thin, the developed electrooptic probe has great potential for detailed electrical characterization in the microscopic regions of high performance electronic products such as the interconnecting parts between LSI packages and printed circuit boards and spaces among different LSI chips in a package.