Takaki Niwa

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We designed a continuously variable-gain low-noise-amplifier (VG-LNA) circuit with a noise figure (NF) of 1.4 dB. This VG-LNA has a diode-loaded emitter follower and a variable-current source. The diode-loaded emitter follower enables gain control without NF degradation at the maximum gain; the variable-current source improves the linearity and widens the(More)
This paper reports low power dissipation 40-GHz frequency dividers fabricated using high-performance AlGaAs/InGaAs HBTs. The high-speed performance of small-emitter-area HBTs was markedly improved by analyzing the device delay time and reducing the emitter resistance R/sub E/. An f/sub T/ of above 110 GHz and an f/sub max/ of 250 GHz were achieved with a(More)
Base-band amplifiers have been demonstrated using AlGaAs/InGaAs HBTs with regrown base contacts. The transimpedance amplifier achieved a bandwidth of 49.3 GHz and a transimpedance gain of 43.7 dB /spl Omega/. The Darlington feedback amplifier achieved a bandwidth of 54.7 GHz and a gain of 8.2 dB. These are the widest bandwidths yet reported for(More)
Optical frontend and distributed amplifier IC modules, both containing GaAs heterojunction-bipolartransistors (HBT), have been developed for 40 Gb/s optical receiver. To achieve high-speed operations, the elements in the modules including the IC and signal lines, were designed to achieve a wider bandwidth with lower electrical reflection. The influence of a(More)
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