Low current wideband amplifier using 0.2 /spl mu/m gate MODFET fabricated by using phase-shift lithography
We have developed wideband amplifier that can keep over 10 dB gain at the drain voltage/current of 2 V/10 mA in the frequency range from 100 MHz to 3 GHz. The fabricated IC achieved low noise figure and high IP3 (output) of 1.4 dB and 30 dBm at 800 MHz, respectively. The present IC employs 0.2 /spl mu/m gate delta-doped MODFET structure fabricated by using phase-shift lithography.
0.15 /spl mu/m T-shaped gate fabrication for GaAs MODFET using phase shift lithography
A new fabrication process of GaAs MODFETs with 0.15 micron T-shaped gate has been developed by using phase shift lithography. Sub-quarter micron footprints of T-shaped gates are defined as line patterns by PEL (pattern-edge line) method using chemically stable positive photoresist. Parasitic capacitances such as C/sub gs/ and C/sub gd/ are also reduced by the air-gap incorporated in the present process. An implemented GaAs MODFET exhibited the NF of 0.36 dB and the gain of 11.5 dB at the frequency of 12 GHz.
Thermal incompatibility analysis of metal-ceramic systems based on flexural displacement data.
The feasibility of simple tests or analytical methods for prediction of residual stress states in metal-ceramic (MC) prostheses has not been demonstrated. Biomaterial metal-ceramic strips have been proposed to provide sensitive measures of transient and residual stress states through the measurement of midpoint deflection after cooling from the ceramic sintering temperature. The objective of this study was to apply the elastic-viscoelastic analogy to calculate transient and residual midpoint deflections in MC biomaterial strips and to compare these values with deflections measured with a beam-bending viscometer (BBV). Calculations and measurements were made for five MC systems that were found from a clinical study to be "thermally compatible" systems. Metal strips, 64 mm in length, 3 mm wide, and either 0.5 mm, 1.0 mm, or 2.0 mm in thickness, were veneered with four 0.25-mm thick layers of opaque porcelain. Midpoint deflection of the MC strips (ceramic oriented in the posterior position) was measured during cooling from an initial temperature of 700 degrees C. In general, the directions of the measured residual deflections did not agree with the "textbook" convention that negative deflections are associated with positive thermal contraction mismatch (alpha(M) - alpha(c) > 0) regardless of metal thickness. For a metal thickness of 0.5 mm, the residual midpoint deflection for all thermal contraction mismatch cases, except one, was positive (upward deflection) whereas the residual midpoint deflections were all negative when the metal thickness was increased to 1 or 2 mm, independent of the thermal contraction mismatch. The best agreement between calculated and measured values of residual midpoint deflection (+16 microns vs. +14 +/- 2.3 microns, respectively was obtained for MC biomaterial strips with a Ni-Cr alloy (0.5 mm thick) while the largest difference (+346 microns vs. +61 +/- 43.8 microns) was obtained for MC bimaterial strips with a Au-Pd allow (0.5 mm thick). In all but one case, changes in deflection direction as a function of metal thickness were correctly predicted by the viscoelastic analysis. The results of this study indicate that a viscoelastic model is useful for estimating thermal compatibility conditions of MC systems.