The dc and ac performance of advanced SiGe:C heterojunction bipolar transistors (HBTs) featuring transit frequency ( $f_{\text {T}}$ ) and maximum oscillation frequency ( $f_{\text {max}}$ ) of 300 and 500 GHz was characterized from 298 K down to 4. 3 K. At 4. https://jalyttlers.shop/product-category/mantel-clock/