A 11.7 GHz 1/8-divider using 43 GHz Si high speed bipolar transistor with photoepitaxially grown ultra-thin base

High-speed bipolar transistor technology using a photoepitaxially grown ultrathin base is presented. Using this technology, a 31 nm base width with BVceo of 3.0 V could be realised. The cutoff frequency of the epitaxially grown base transistor (EBT) drastically improved from 32 GHz to 43 GHz as the base width decreased from 66 nm to 31 nm because the base transit time was effectively reduced. However, the minimum ECL (emitter coupled logic) gate delay time of the EBT was observed in the case of a 66 nm base width to be 58 ps at 7.5 mW/gate because the ultrathin base increased the base resistance. There was trade-off between the cutoff frequency and the ECL gate delay time. The authors integrated the EBT into a 1/8-divider, and observed a maximum operating frequency of 11.7 GHz.<>