Study on ESD Effects of GaAs HBT Power Amplifiers for DCS/GSM Dual Band Handsets
Study on electrostatic discharge (ESD) impact on the GaAs HBT power amplifier (PA) in DCS/GSM dual band handsets is performed in this paper, which has been regarded as its main reliability issue accounting for most failures of radio frequency integrated circuits. In order to suppress the positive ESD impact on the PA in an effective but very economic way, a set of forward ESD diodes at its input port is replaced by the PN junction of GaAs HBT transistor in its first-stage. Alternatively, to introduce a set of thin film resistors (TFRs) at the front of a HBT transistor is necessary for improving the S11-parameter and stability of PA; however, their electrothermal breakdown possibilities do exist. Therefore, both performance degradation and breakdown events of several PA dies are measured for different ESD voltages described by the human body model, with different TFRs chosen for both DCS and GSM bands, respectively. Their transient temperature responses are also captured and compared for different ESD waveforms, which are predicted using the in-house developed algorithm based on the hybrid time-domain finite-element method.