Characterization of the Noise Parameters of SiGe HBTs in the 70–170-GHz Range

Abstract

Noise parameter ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> , <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Z</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">opt</sub> , and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R n</i> ) measurements of SiGe HBTs are provided for the first time in the 70-170-GHz range. In the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">W</i> -band, this is accomplished by integrating on a single chip a source impedance tuner with the device-under-test and a low-noise amplifier with 3.8-dB noise figure. Noise-figure measurements were performed over multiple source impedances using a commercial single-sideband downconverter. In the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</i> -band, where off-chip setup losses are overwhelming, the source impedance tuner, the transistor under test, and the entire receiver with a noise figure of 10 dB were integrated on a single silicon die, and direct noise-figure measurements were conducted first on the test setup with the transistor under test, and next on the reference receiver without the test transistor. Both analog and digital source impedance tuners, based on n-MOSFET variable resistors, n-MOSFET switches, and accumulation-mode varactors, have been designed and characterized. Finally, the existing technique to extract the SiGe HBT noise parameters from <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Y</i> -parameter measurements, without any noise-figure measurements, is refined to include noise correlation and is validated up to 170 GHz. The measured source-pull and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Y</i> -parameters results show that the minimum noise figure of state-of-the-art SiGe HBTs remains below 5 dB throughout the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</i> -band.