Submillimeter-wave Integrated Circuit Research Articles

20-nm In0.8Ga0.2As MOSHEMT MMIC Technology on Silicon

High-gain millimeter-wave monolithic integrated circuit (MMIC) amplifiers have been developed, based on a planar metamorphic 20-nm gate length InGaAs metal–oxide–semiconductor high-electron-mobility transistor (MOSHEMT) technology on Si. Therefore, an Al2 O 3/Hf O 2 layer stack was deposited as a gate dielectric directly on top of an In0.8Ga0.2As channel by atomic layer deposition. The III–V heterostructure was epitaxial grown on a GaAs wafer and subsequently direct wafer bonded to a Si substrate, leading to a high-quality III–V channel formation on Si. The gate layout was optimized for millimeter-wave and submillimeter-wave integrated circuit applications using T-gates and wet chemical recess etching to minimize the parasitic gate capacitances. For a $2 \times 10 \,\,\mu \text{m}$ gate width transistor, a transit frequency $\text{f}_{\textrm {T}}$ of 200 GHz and a record maximum oscillation frequency $\text{f}_{\textrm {max}}$ of 640 GHz were extrapolated. A realized three-stage cascode amplifier circuit demonstrated a maximum gain of 21 dB at 278 GHz and a small-signal gain of more than 17 dB between 222 and 284 GHz. The total chip size of the millimeter-wave amplifier MMIC was only $0.5\,\,\times \,\,1.2$ mm2. To verify the RF performance of the III–V MOSHEMT on Si technology, all devices and circuits have been reproduced using an InGaAs MOSHEMT on GaAs technology, which has been processed simultaneously within the same wafer batch and achieved almost identical results.

A study of planar Goubau lines (PGLs) for millimeter‐ and submillimeter‐wave integrated circuits (ICs)

AbstractIn this paper, a new type of planar Goubau line (PGL) for millimeter‐ and submillimeter‐wave applications is proposed for use in wideband integrated circuits. The configurations of these modified Goubau lines are examined and the parameters are provided. The performances of these lines are studied in detail. Characteristics of lines with different dimensions are calculated and displayed. Comparisons with other types of transmission lines are also performed. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 290–293, 2004; Published online in Wiley InterScience (www.interscience.wiley.com).

Radiation Characteristics of a Dielectric Slab Waveguide Periodically Loaded with Thick Metal Strips

A theoretical analysis is presented for the radiation characteristics of a dielectric slab waveguide periodically loaded with thick metal strips. A boundary-integral-equation formulation is employed to describe the fieIds in the grating layer. Through numerical calculations, we show that the leakage constant of the fundamental TM mode is much larger than that of the fundamental TE mode. This property will find application in mode filters for millimeter- and submillimeter-wave integrated circuits.

Design of Dielectric Ridge Waveguides for Millimeter-Wave Integrated Circuits

All-dielectric ridge waveguides may be useful as elements of millimeter- and submillimeter-wave integrated circuits; A planar metallic V-coupler can be used to couple energy between the guide and small circuit elements such as diodes. Desirable characteristics in such a guide/coupler system are a) quasi-single mode propagation; b) low radiation loss in bendy c) low coupling loss between guide and devices and d) adequate physical strength. In this paper, we discuss the general problem of designing guides and couplers to obtain the desired characteristics. The principal method used is simulation in the range 2-7 GHz. We find that with good compromise designs, typical coupling loss between waveguide and a small device is about 1.4 dB, exclusive of dielectric loss and ohmic loss in the coupler.

Propagation Properties of a Planar Dielectric Waveguide with Periodic Metallic Strips

A dielectric waveguide with periodic metallic strips suitable for millimeter-wave and submillimeter-wave integrated circuits is analyzed by a rigorous formulation. The accuracy of the solution of our analysis can be systematically improved by increasing the size of the matrix associated with the eigenvalue equation. Stopband properties are numerically presented as a function of the spacing and width of metallic strips and dielectric profile. It is found that there is a difference in the stopband properties of TM and TE modes. Experimental results for the band reject filter are also presented to verify the validity of our analysis.