Parameter extraction technique for HBT equivalent circuit using cutoff mode measurement

A parameter extraction method based on the S-parameter measurements of the heterojunction bipolar transistors (HBTs) biased to cutoff is proposed. This method is applied to confirm the results for the RF probe pad and interconnection pattern parasitics obtained from the special test structures, and to determine some of the device capacitances of the HBT. The remaining device parameters are extracted by the S-parameter measurements of the devices biased to the active mode. The extraction technique gives good agreement between the equivalent circuit and the measured S-parameters of the HBT including probe pads and interconnections