Thermal Effects in Current Feedback Operational Amplifiers in Bipolar Technology

This paper presents an analysis of the of self-heating on the key performance parameters of the high speed current feedback operational amplifiers (CFOA) designed using SOI bipolar transistors. The analysis shows that the frequency response of the open-loop transimpedance and common-mode rejection ratio (CMRR) of the CFOA is highly affected by the dynamic self-heating induced errors. A large- signal step response of the CFOA in the closed-loop configuration, can have a large thermal tail due to the static self-heating effects. These thermal effects are studied using the conventional topology of the CFOA and different topologies of the CFOA are identified to mitigate such effects. The classical and optimized CFOA circuits are simulated to demonstrate the thermal effects using the vertical bipolar inter-company (VBIC) model in the SPECTRE simulator.