Shigenori Aoki

A flip-chip MMIC design with coplanar waveguide transmission line in the W-band

This paper describes a design method for flip-chip monolithic millimeter-wave integrated circuits (MMICs) with a coplanar waveguide (CPW) transmission line for W-band applications. We proposed a test structure for obtaining accurate flip-chip CPW line models. We examined the transmission line characteristics of the CPW line using the test structure in the millimeter-wave range and modeled them. Using the CPW line models, we designed and fabricated both two- and three-stage amplifiers using 0.15-/spl mu/m InGaP/InGaAs high electron-mobility transistor technology. The maximum power gain of the two-stage amplifier is 12 dB at 79 GHz. The three-stage amplifier has a maximum power gain of 16 dB at 77 GHz. The agreement of measured S-parameters with calculated results demonstrates that the proposed test structure is suitable for characterizing flip-chip CPW lines and provides very accurate models.

Electrooptic planar deflector switches with thin-film PLZT active elements

First prototypes of electrooptic (EO) planar deflector switches (PDSs) are fabricated with hybrid integration on Si substrates. Planar optical modules, made in silica-on-silicon technology, consist of input and output (I/O) waveguide microlenses facing each other and slab waveguides in between. The modules interconnect the I/O fibers with laterally collimated light beams less than 400 /spl mu/m in width at distances up to 100 mm with losses lower than 3 dB. Thin lead lanthanum zirconium titanate (PLZT) films with prism-shaped electrodes grown on SrTiO/sub 3/ substrates form the deflector elements. The PLZT films are more than 10 /spl mu/m thick with EO coefficients about 40 pm/V. The deflector assembly technology provides chip vertical positioning accuracy better than 1 /spl mu/m. The deflector chips are attached to the optical substrates with thermo-compression flip-chip bonding. The optical power losses of the modules with test silica chips can be as low as 3.6 dB. However, the lowest module losses achieved with PLZT are about 10 dB. The channel-to-channel switching operations are demonstrated at about 40 V and switching times less than 500 ns.

A flip chip bonding technology using gold pillars for millimeter-wave applications

This paper reports a flip chip bonding technology for a millimeter-wave monolithic integrated circuit (MIMIC) using gold micropillars with a controlled air gap instead of conventional wire bonding. We focus on their electrical performance in the W-band and their reliability against stresses expected in automotive radar applications.

Integrated waveguide micro-optic elements for 3D routing in board-level optical interconnects

Planar waveguides and embedded microelements such as 45o vertical mirrors, lateral mirrors, bends, and microlenses comprise main building blocks of the waveguide-based optical printed circuit boards (PCB) for board-level optical interconnects (OI). These microelements enable a variety of three dimensional (3D) routing architectures which are required to support high density interconnects in optical boards. Optical polymers have proved to be the materials of choice for large-scale OI modules with propagation dimensions exceeding 100 mm. In order to meet the loss budget available for the integrated OI modules, the polymers are expected to have optical losses less than 0.05 dB/cm. Both channel and slab waveguides can be used to transmit the signals between the input and output ports. In the case of channel waveguides, the critical issues are the waveguide core shaping, propagation losses and ability to form various passive elements such as bends, crossings and reflective mirrors. In the case of slab waveguides, two dimensional waveguide microlenses have to be designed to collimate the light beams for propagation at longer distances with the controllable beam divergences. The 45o micromirrors can be used to couple the light signal in and out of the waveguiding layer and enable 3D routing of the optical signal in the waveguiding layers. In this work, we present the experimental and computational results on the development of different waveguide devices and microelements for the board level OI.

76 GHz Flip-chip MMICs in Through-hole Packages

We have developed novel hermetically sealed package with through-hole for the use in low-cost millimeter-wave applications. The package is available with specifications ranging from DC to 85 GHz. The insertion loss at feed-through of the package is less than 0.5 dB at 76 GHz. It is especially suitable for flip-chip MMICs. We have also developed 76 GHz flip-chip MMICs for automotive radar applications. A combination of flip-chip bonding technique and new package will provide a low cost millimeter-wave module. The MMIC modules have the following characteristics: The 76 GHz 4-stage amplifier has a gain of 22 dB. The frequency mixer with 1-stage amplifiers has a conversion loss of 2 dB. The 38/76 GHz frequency doublers with the 38 GHz 1-stage amplifier provide an output power of 0 dBm. The voltage-controlled oscillator provides an output power of 6 dBm. The 76 GHz SPDT switch has an insertion loss of 6 dB and an isolation of 15 dB.

Planar hybrid polymer-silica microlenses with tunable beamwidth and focal length

Thermally tunable planar microlenses have been fabricated with a hybrid process utilizing silica-on-silicon and polymer planar lightwave circuit technologies. The silica microlens has a double concave gap filled with an optical polymer. The lens collimates the light beam with a beamwidth of less than 450 /spl mu/m at distances up to 100 mm. The experiments presented demonstrate that by varying the lens temperature in a range of 60/spl deg/C the beamwidth can be tuned by /spl plusmn/40% at different distances from the lens. The beam-propagation-method simulations show that adjusting the lens curvature can control the beamwidth tunability range and thermal sensitivity. That allows optimization of the lens designs for different applications.

A flip-chip MMIC design with CPW technology in the W-band

We designed and fabricated a W-band flip-chip MMIC amplifier with a coplanar waveguide (CPW) transmission line using 0.15 /spl mu/m InGaP-InGaAs HEMT technology. In addition, we present a test structure for obtaining an accurate flip-chip CPW line model, and demonstrate a two-stage flip-chip MMIC amplifier with a gain of 12 dB at 79 GHz to validate this model.

High bandwidth optical interconnection for densely integrated server

We developed optical interconnect technologies, i.e., an optical mid-plane, high-density connector, and a compact transceiver for future servers that enable high-bandwidth and dense integration. Using these technologies, 1500 optical connections and 37.5 Tb/s of bandwidth were built in a blade-server form factor.

Optical interconnect architecture for servers using high bandwidth optical mid-plane

We describe an interconnect architecture that utilizes high bandwidth optical mid-plane. Enabling technologies for high density optical mid-plane are discussed. We developed a prototype to determine the feasibility. The results showed proposed architecture is practical.

Integrated 8×8 Electro-optic High-speed Switch for Optical Burst Transport Networks

We developed 8 times 8 beam-deflecting optical switch with a switching speed within one microsecond utilizing electro-optic effect of PLZT. A newly-developed radial optical path design and putting-in packaging structure with a monolithic PLC platform were applied.