HB-based CAD-oriented dynamic stability analysis of circuits and devices: Application to the assessment of thermal instabilities in multifinger HBTs

Assessment of Thermal Instabilities and Oscillations in Multifinger Heterojunction Bipolar Transistors Through a Harmonic-Balance-Based CAD-Oriented Dynamic Stability Analysis Technique

“…First, we add an introduction to the stability analysis technique in order to make this paper self-consistent and allow the reader to have a better insight into the implementation. Furthermore, we provide insights into the appearance of electrothermal oscillations, which were reported for multifinger device layouts in [8]. A detailed numerical analysis of the dynamic behavior of a two-finger device is added, and the onset of the oscillations is explained on the basis of a more intuitive electrothermal circuit model.…”

“…This allows one to define the vector of the time samples (7) and the vector of the harmonic amplitudes (8) The two sampled representations of are related by an invertible linear operator (the discrete Fourier transform operator and its inverse [12]) (9) whose detailed expression can be found in [6] and [12]. Similarly, the harmonic amplitudes of the time derivative (denoted here with a dot) of are linearly related to the harmonic amplitudes by means of a tridiagonal square matrix (see [6] for the expression) (10) where denotes the collection of time samples of , and .…”

“…The stability assessment technique described in Section II is applied to the study of the electrothermal behavior of multifinger GaAs-based HBTs [8]. The HBT electrical model exploits a measurement-based temperature-dependent Gummel-Poon model [13] for forward dc operation, completed by extrinsic resistances and nonlinear base-emitter and base-collector capacitances (see Fig.…”

“…In this paper, we exploit the proposed Floquet-multiplier-based technique to show an extremely varied set of dynamical behaviors, for instance, versus the device layout (namely, the number of emitter fingers). A further advantage of the present approach is the possibility to accurately and efficiently assess the effect of electrical or thermal stabilization techniques [8]. Two main additions are presented here with respect to [8].…”

“…A further advantage of the present approach is the possibility to accurately and efficiently assess the effect of electrical or thermal stabilization techniques [8]. Two main additions are presented here with respect to [8]. First, we add an introduction to the stability analysis technique in order to make this paper self-consistent and allow the reader to have a better insight into the implementation.…”