SET-Induced Dropout and Recovery of Cross-Coupled and Differential-Colpitts Microwave Oscillators Using SiGe HBTs

Radio frequency (RF) communications systems in space flight are subject to single-event upsets (SEUs) due to dropout of the local oscillator (LO) during a single-event transient (SET), named here as single-event dropout (SEDO). If the duration of the SEDO is substantial, it inevitably compromises data. To help alleviate SEUs due to SEDO, the present work compares the dropout dynamics and recovery times of two types of RF
$\boldsymbol {LC}$
oscillators with matched performance: the cross-coupled and the differential-Colpitts. The SEDO responses of both oscillators were tested using a pulsed laser to deposit charge via a two-photon absorption (TPA) process. For matched electrical performance and laser excitation conditions, the Colpitts oscillator demonstrated
$14\times $
faster recovery. This improved response was examined using a hybridized circuit/technology computer-aided design (TCAD) simulation approach, and it was determined that a lower impedance at the bases of critical oscillating transistors naturally reduces the SEDO sensitivity for Colpitts oscillators. While cross-coupled oscillators are widely used, the present work demonstrates that Colpitts oscillators should instead be considered in frequency synthesizers to mitigate SEUs due to SEDO in oscillators.