Sub-1-K Operation of SiGe Transistors and Circuits

Abstract

We present the first measurement results for silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) and SiGe BiCMOS circuits operating in the sub-1-K regime. Robust transistor operation of a first-generation 0.5 times 2.5 times 4-mum <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> SiGe transistor is demonstrated at package temperatures as low as 300 mK. In addition, a SiGe BiCMOS bandgap voltage reference is verified to be fully functional at operating temperatures below 700 mK. The SiGe voltage reference exhibits a temperature coefficient of 160 ppm/degC over the temperature range of 700 mK-300 K.