Effect of pad and interconnection parasitics on phase delay of transconductance in advanced bipolar transistors

An analytical expression is developed for determining the accurate phase delay of transconductance or current gain in a small-signal equivalent circuit, including RF probe pad and interconnection parasitics and HBT extrinsic elements. Using this new expression, it is demonstrated that collector resistance, collector interconnection resistance, and pad capacitances have a significant influence on the phase delay.