An analytical and experimental investigation of the cutoff frequency fT of high-speed bipolar transistors

The effects of vertical and lateral structures on cutoff frequency and breakdown voltage are investigated for high-speed bipolar transistors. The cutoff frequencies are examined in the range from 2.5 to 80 GHz by analysis and from 3 to 20 GHz by experiment. To attain the maximum cutoff frequency, it is predicted that the collector width, the base width, and the collector concentration should be 0.12 μm, 0.07 μm, and 1.2×10¹⁶ cm^-3, respectively, and that in this scaled transistor, breakdown voltages, BV_CE0 and BV_C8O should be reduced below 3 and 7.7 V respectively