Direct measurement of C/sub be/ and C/sub bc/ versus voltage for small HBT's with microwave s-parameters for scaled Gummel-Poon BJT models

A novel method for determining the junction capacitances versus voltage in heterojunction bipolar transistors (HBT's) using s-parameters at microwave frequencies is presented. This new technique has several advantages over traditional approaches, which include: (1) it profiles capacitance at greater forward bias; (2) it enables the direct measurement of minimum geometry transistors; (3) it allows for the accurate extraction of scaled HBT model parameters with emitter length; and (4) it results in improved pad parasitic deembedding for accurate modeling. Both the capacitance-voltage and large-signal HBT model results are shown.