Thermal effects and analysis on analog integrated circuit design

Dielectrically Isolated Bipolar Junction Transistors (DIBJTs) are used in various high frequency applications. High frequency application requires high gain in these devices, and the gain of DIBJTs is significantly higher than complimentary metal-oxide-semiconductor (CMOS) devices. Thermal heating from the devices itself and from adjacent devices change the device characteristics. This thesis explores the thermal effects from self heating and inter-device heating (thermal coupling) in the time domain of the device as well as at the circuit level.;This research measures and analyzes the thermal modeling of DIBJTs. Different measurement procedures are explored and implemented. After the collection of data from the devices, calculations and analysis of the data were studied. The data was used to characterize the thermal network of the device model file. Finally, real-time reasons were compared with simulated results using the redefined thermal model.;DIBJTs are an essential building block of high speed IC design [2]. Full DIBJTs are fabricated by using trench isolation and silicon-on-insulator (SOI) technologies. Advantages of these transistors include reduced parasitic capacitance, low leakage current, latch-up free and radiation hardened circuitry. On the other hand, a major disadvantage of full DIBJTs is its poor thermal conductivity of the dielectric. The trench silicon oxide isolation has roughly 1% of the thermal conductivity of silicon. Because the die concentration and operating current density tend to increase, to meet the demand of the marker, bipolar transistors exhibit greater sensitivity to thermal effects caused by excessive self-heating, adjacent device heating, and packaging [3].;For the research work National Semiconductor's DIBJTs have been used to extract real work results. The process for these devices to manufacture is called VIP10. Vertical Bipolar Inter Company (VBIC) model is used to model these transistors. A 1-pole thermal circuit network is present in the VBIC network. A more complex thermal model has been developed to better match the real world measurement results from these transistors in time domain. The complex thermal model consists of five time constants circuit. Further analysis was done to convert multiple pole circuit models to single pole circuit models. Furthermore, the effects of adjacent heating devices were also explored.