Characterization of Dynamic Large-Signal Operating Limits and Long-Term RF Reliability of SiGe HBTs

The dynamic (RF) large-signal operating limits of advanced SiGe HBTs are systematically explored and discussed. Experimental results of long-term RF stress tests performed with a passive load-pull system are presented and analyzed. The experimental data demonstrate that SiGe HBTs are extremely robust and can be operated statically and dynamically far beyond the open-base collector-emitter breakdown voltage without noticeable degradation during the long stress times. The results suggest that only extremely non-linear large-signal operating conditions cause significant degradation of the admittance parameters. RF stress tests of HBTs with different emitter widths suggest that the measured degradation is area-related and can be attributed to the minority carrier charge storage and transport.