Takekazu Okada

Mechanically tunable MSW bandpass filter with combined magnetic units

An MSW (magnetostatic wave) bandpass filter with combined magnetic units composed of main and submagnetic units has been developed. Its volume is reduced to one fifth that of conventional yttrium-iron-garnet (YIG)-sphere filters. The filter can be tuned mechanically and keep the same shape of transmission response at 2.5 approximately 2.75 GHz. The insertion loss can be kept less than 3 dB within 20-MHz bandwidth by adjusting the magnetic field distribution.<<ETX>>

Low loss two-port lumped element isolator using improved gyrator circuit

Design equations for a new low loss two-port isolator are derived by analyzing the conventional two-port isolator and improved gyrator circuit. The isolator performance is simulated using the admittance matrix; the result provides an insertion loss, 0.25dB less at 1920MHz to 1980MHz, compared to conventional two-port isolator. Using these design equations, a 3.2X3.2X1.5mm 3 cellular phone isolator which insertion loss is 0.36dBmax. at 1920MHz to 1980 MHz, is realized.

Low Loss Lumped Element Isolator Using Gyrator Circuit With Two Asymmetrical Electrodes

The equations of the insertion loss and the isolation bandwidth of low loss two-port isolator were derived from equivalent circuit using perturbation theory. The equations show that the insertion loss gets lower in proportion to the ratio of inductors of two electrodes, while the isolation bandwidth gets narrower nearly in the proportion to the ratio. A 3.2 times 2.5 times 1.4mm3 cellular phone isolator which volume was 44% of the conventional products was realized using two electrodes of asymmetrical structure that inductance of one was much larger than that of the another

A miniaturized low-spurious 1.9 GHz MSW band-pass filter using YIG resonators with multi metal rings

A simple technique for forming multiple metal rings on both sides of a YIG element has been developed to suppress the spurious responses of YIG resonators. By using this resonator, a 10-mm*5-mm*4-mm/sup 3/ two-stage MSW (magnetostatic wave) bandpass filter has been developed. The insertion loss is about 2 dB at 1.9 GHz and the suppression of spurious response is 25 dB. The filter is useful for signal processing in the circuits of portable microwave telecommunication sets because of its compact dimensions and excellent filter characteristics.<<ETX>>

Tunable isolator using variable capacitor for multi-band system

A novel tunable isolator for multi-standard mobile handsets has been successfully developed. A new circuit configuration for tuning operation frequency of the isolation is proposed. It shows that the isolation band is tuned widely by varying the variable capacitor value without increasing the insertion loss. A 1.5 × 0.9 × H0.4mm3 Core-Isolator and a 0.5 × 0.5 × 0.2mm3 (BaSr)TiO3 (BST) variable capacitor have been fabricated on a PCB. By using this circuit, usable isolation band could be expanded to 698-915MHz, which is 6 times wider than conventional one. The developed isolator keeps other characteristics such as 0.6dB max of insertion loss, 12dB min of isolation and -60dBc level of ACLR (5MHz).

Spin wave isolator based on frequency displacement nonreciprocity in ferromagnetic bilayer

We demonstrated the spin wave isolator using bilayer ferromagnetic media comprising single crystalline and poly-crystalline yttrium iron garnet films, which can control the propagation frequency of magnetostatic waves by the direction of applied magnetic field. This isolators property does not depend on their thickness then this can be downsized and integrated for nano-scale magnonic circuits. Calculated dispersion relationship shows good agreement with measured one.

A novel resonance absorption isolator with T-microstrip

A novel resonance absorption isolator for cellular phone terminals has been developed, which employing T-microstrip line on a ferrite blank. Reduction of stray capacitance of the microtrip makes it possible to realize improvement of the insertion loss and to decrease the additional circuit element number. The operation theory of the isolator has been confirmed by using EM field analysis and circuit simulator. The developed isolator is composed of only two elements which are a 1.0×0.8×0.6mm3 Core-Isolator and a 0.4×0.2×0.2mm3 ceramic capacitor. Its insertion loss and isolation performances are 0.5dB max. and 9.2dB min., respectively at 1.9GHz band.

Low-profile broadband Core-Isolator for multi-band module

A novel broadband Core-Isolator for modules of multi-standard and multi-band mobile handsets has been developed successfully. A new circuit configuration for extending the isolation frequency band is proposed. The equations of the insertion loss and the isolation bandwidth of a two-port isolator with resonant elements are derived from equivalent circuit using perturbation theory. They show that the isolation bandwidth gets wider depending on the ratio of inductor and capacitor of resonant elements without increasing the insertion loss. A 1.5 × 0.9 × 0.4 mm3 Core-Isolator with two electrodes of asymmetrical structure has been fabricated, which is mounted on a module substrate with resonant elements. It has an insertion loss of 0.5dB and an isolation of 10dB at 824–915MHz which is twice wider than conventional one.