Thermal Effects On Analog Integrated Circuit Design

Analog Integrated Circuit design (IC) is a big challenge in this modern age. Thermal effect has a substantial role in analog ICs performance. Thermal effects on analog IC design have been investigated in this dissertation project. National Semiconductor Corporation's Vertical Bipolar Inter-Company (VBIC) model of dielectrically isolated bipolar junction transistors (DIBJT) with VIP10 and VIP11 processes have been used for the research. These devices are used for the high speed IC design. Self-heat generated inside these devices is confined within the device and degrades the device performance. In addition, the thermal characteristic of a device surrounded by the multiple adjacent devices may be different from that of an isolated device because of the thermal coupling effect. These in turn substantially affects the circuit's frequency, dc and time response. This research explored the modeling, characterization, and extraction of the thermal resistance which accounts for both self-heating and thermal coupling effects. Thermal resistance for the self-heating is analyzed and extracted in both frequency and dc methods. Thermal coupling resistance is extracted in dc method with different spacings among the adjacent devices. A new small signal circuit model of a DIBJT is developed for including the self-heating effect. A five element model of the thermal resistance is studied. This five element thermal resistance includes components of thermal resistances from all sides of a dielectrically isolated bipolar device. This includes adjacent device or thermal coupling effect as well. These elements describe multiple thermal poles. A simple time domain analysis is done to show their existence. On the other side, the thermal effects have significant impact on the several analog design's performance or parameters. Therefore, several analog circuits are designed and examined the thermal effect. They are current mirrors, Vbe based bootstrap current source, and high order bandgap reference. Thermal characterization of Y-parameters and output resistance are done as well. Theory, simulations, and measurement results agree with the modeling, characterization, and designs presented in this dissertation. The simulations and measurements have done primarily with cadence Spectre and HP4395A network analyzer, Agilent 87511A S-parameter test set, HP4142B Modular DC Source/Monitor, and ICCAP interfaced evaluation system respectively.