Electro-Thermal Simulation of a Bandgap
In this paper we researched an influence of device thermal coupling on bandgap characteristics. The straightforward RFIC / MMIC circuits, the foundry provided design-kits (DKs) together with the device models HICUM, MEXTRAM and VIBC are used. The provided device models mostly include the self-heating parameters. However, self-heating parameters are modeled only for the intrinsic device but not for the surrounding devices. Furthermore, layout and packaging issues, which have a strong influence on the thermal performance of the ICs are not considered by the foundry provided device models. This causes inaccurate simulation results of aforementioned bandgap circuit in highly integrated designs with several power devices in a close proximity. The proposed approach is based on the electrical and thermal co-simulation and optimized material stack. Co-simulation utilizes power dissipation data from the circuit simulator and passes the value to the thermal solver. The solver extracts device information and connectivity from layout and calculates device temperature based on the current power dissipation value. The temperature value is transferred back to a circuit simulator to calculate new power dissipation. This way, the thermal solver iterates with the circuit until a converged solution is reached. The process layer stack and all the required information are embedded into the foundry provided process design kit (PDK); hence allow the designer performing the electro-thermal simulations under the same design environment. The electro-thermal simulation shows significant output voltage change at high temperatures. Using the proposed flow, the circuit designers are capable to simulate the temperature affects and be aware of them before the tape out thus the reduce the malfunctioning risk of ICs due to unexpected thermal issues.