Munenari Kawashima

A novel broadband active balun

We have developed a novel broadband active balun. It consists of series-connected common-gate FETs and a common-source FET. The active balun achieved broadband characteristics by using series-connected common-gate FETs with the same gradient as the phase performance of the common-source FET. From 500 MHz to more than 10 GHz, the fabricated active balun shows a phase error of less than 5 degrees. A fabricated single balanced mixer using the proposed active balun had LO suppression of more than 40 dB over an LO frequency range of between 1 and 5 GHz.

Broadband Low Noise Amplifier with High Linearity for Software-Defined Radios

We propose a broadband low noise amplifier with high linearity performance. The amplifier achieves broadband, low noise performance and high linearity using a bias circuit with high impedance. The bias circuit consists of an inductor, a resistor, and a current source. The circuit obtains high impedance using a high resistive component. From 0.8 to 5 GHz, the low noise amplifier shows an S21 of 20plusmn1 dB and an Sll of less than -9 dB. The noise figure is 1.5-2.7 dB for frequencies from 0.5 to 5 GHz. The output 1-dB compression point at 2 GHz is +6.3 dBm.

Broadband and compact 3-dB MMIC directional coupler with lumped element

This paper proposed a broadband and compact 3-dB MMIC edge-coupled directional coupler. The proposed coupler consists of eight stepped-impedance coupled sections and a tiny capacitor. The capacitor is constructed by using the MIM capacitor process and is located on the center of the coupler. The capacitor and stepped structure effectively realize 3-dB coupling and enhanced amplitude/phase characteristics. A millimeter-wave prototype MMIC coupler is fabricated on the 100-µm thick GaAs substrate by using the GaAs pHEMT process. The total coupler length is only 440 µm. The fabricated coupler achieves a coupling loss of −4dB±0.5dB from 30 GHz to 69.3 GHz. The output amplitude and phase imbalances are less than 1.4 dB and 90 degrees ± 5 degrees at the same frequency range, respectively. The proposed MMIC coupler promises very compact and broadband MMIC.

A broadband low-noise wide dynamic range SiGe front-end receiver IC for multi-band access points

A broadband, low-noise, wide dynamic range front-end receiver IC is reported. It uses 0.25 μm SiGe BiCMOS process technology and consists of broadband variable gain low noise amplifiers (VGLNAs), down-conversion mixers, step attenuators, and buffer amplifiers. It can receive triple-band signals concurrently, and the chip size is only 3mm × 3mm. Its measured noise figure was under 3.2 dB and the measured conversion gain was around 30 dB in the broad frequency range from 300 MHz to 3 GHz. It has a wide gain control range of around 100 dB; 50 dB is controlled by the VGLNA and the step attenuator, and 50 dB by the mixer with novel relative power control method using dual LO signal. The gain control enhances the input 1dB compression point from -40 dBm to -21 dBm.

Development of improved 24GHz-band class-F load rectennas

We improved class-F load rectennas at 24GHz which optimal load and optimal input power were different from the designed ones. We focused on the class-F load which is the most important point in class-F load rectennas. Through analysis of electromagnetic field, we clarified that we could simulate accurately with a circuit analysis simulator when the discontinuity in a microstrip line was small and the thickness of the substrate was thin enough to suppress the effect of the surface wave. We also found that 3rd harmonics management was enough for class-F load rectennas to produce high efficiency. We designed and fabricated the new-type class-F load rectennas. We could not improve the efficiency, but we revealed that the disagreement of the optimal load and the optimal input power was not caused by the effect of the surface wave.

Development of MMIC rectenna at 24GHz

Microwave Power Transmission (MPT) can be applied to a greater number of applications provided that higher frequency MPT systems are developed. In particular, we need high efficiency rectennas at higher frequencies. We developed a monolithic microwave integrated circuit (MMIC) rectenna with a resonant frequency of 24 GHz, with dimensions of 1 mm × 3 mm, and whose maximum RF-DC conversion efficiency is 47.9% for a 210 mW microwave input power at 24 GHz with a 120 Ω load. We intend to apply this rectenna to realize simultaneous power and information transmission.

Angle selective high absorption by a mushroom metasurface at V-band

A metasurface consisting of a periodic array of mushroom structures is designed and tested to demonstrate a strong angle selective absorption for TM incident waves from free space at V-band. An absorption as high as 35.6 dB is experimentally obtained with the incident/reflection angle of θ = 7 deg at 67.3 GHz. Time domain measurements reveal that there exist reradiated waves with a longer decay than that of the direct specular reflection and the absorption is considered to be due to a cancellation of the direct specular reflected waves and the reradiated waves.

A Monolithic Microwave-Integrated Circuit Doubler Using a Resonant-Tunneling High-Electron-Mobility Transistor

A resonant-tunneling high-electron-mobility transistor (RTHEMT) doubler with matching circuits is described. We obtained a large conversion gain even at low input power, which was due to the strong nonlinearity of the RTHEMT. The conversion gain was 1.5 dB for a -10 dBm input signal at 2.4 GHz. Power consumption was only 4 mW, which was one-fifth that of a doubler using a GaAs metal-semiconductor field effect transistor (MESFET). The maximum reflection loss was 6 dB at 2.4 GHz.

Millimeter-wave/terahertz circuits and transceivers for broadband wireless systems

This paper reviews millimeter-wave and terahertz wireless technological developments in NTT Corporation. We show a 60-GHz band transceiver with low temperature co-fired ceramic-system-in-package modules and MMICs. We also show a 120-GHz band wireless link using InP HEMT MMICs for 120-GHz band, 10-Gb/s broadband wireless link systems.

A Dual-Band VCO Integrated with RF-MEMS Switches and Inductors

The authors propose a dual-band VCO integrated with RF-MEMS devices using flip-chip mounting. A wide frequency band switching capability is realized using low-loss RF-MEMS switches and high-Q inductors to switch one of series-connected inductors. A VCO with RF-MEMS was fabricated and measured. The carrier frequency of the dual-band VCO was tuned from 4.443 to 4.695 GHz and from 5.106 to 5.411 GHz. The phase noise was -103 dBc/Hz at a 1-MHz offset from the carrier frequency of 4.443 GHz