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Three wideband amplifiers in double-heterojunction bipolar transistor technology have been designed and measured. The amplifiers use different types of distributed amplifier (DA) topologies, all based on cascode gain cells. A single-stage DA design achieves 7.5-dB gain and 192-GHz bandwidth and a two-cascaded single-stage DA achieves an average gain of 16 dB with a bandwidth of 235 GHz. The third circuit is a conventional DA with more than 10-dB gain from 70 kHz up to 180 GHz. To the authors' best knowledge, the single-stage DA and the two-cascaded single-stage DA are the widest band amplifiers in any technology reported to date. Furthermore, the conventional DA has a record bandwidth for circuits in conventional DA topology with gain from near dc.

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