Analysis of temperature and process variation effects on photo sensor circuits using device/circuit mixed-mode simulations
Impact of temperature and process variations on the output voltage variations of CMOS photo sensor is discussed. As temperature becomes high, output voltage (Vout) decreases because of the amplifier characteristics. But above 350 K, Vout increases in a weak light intensity range. The process variations have an impact when the operation temperature is high and irradiating light intensity is low. We also estimate influence of additional drive-in process, and find the sensitivities of process variation to increase. To consider both process and temperature variations at the same time, we evaluate Vout variation with mixed-mode simulation.
Physics-Based Photodiode Model Enabling Consistent Opto-Electronic Circuit Simulation
The paper developed a photodiode (PD) model for circuit simulation considering, contrary to existing models, the transient carrier generation explicitly in the solution of the continuity equation. The developed model is compatible with conventional compact electrical device models and is demonstrated to enable accurate simulation of opto-electronic integrated circuits. The electric field distribution along the depth direction of the PD is found to cause a tail in the photo current, which has an adverse effect on optical response of PD and the performance of opto-electronic circuits. The developed opto-electronic circuit model is also applicable to predict how circuit performance is improved with respect to the improvement of photo diode characteristics
Intensification of Bubble Disintegration and Dispersion by Mechanical Stirring in Gas Injection Refining
Water model experiments were performed for establishing highly efficient gas injection refining processes. Mechanical stirring was applied to disintegrate the injected bubbles and to disperse them widely in the bath. The bubble disintegration and dispersion were investigated by changing rotation mode (direction of rotation), rotation speed, blade size of the impeller and gas flow rate. Forward rotation of the impeller induced a stable tangential flow and could not disperse bubbles in the bath due to formation of a vortex around the impeller shaft. The tangential flow could be suppressed by forward–interrupt rotation, which could reduce the vortex formation to some degree. However, forward–interrupt rotation could not disperse the bubbles widely in the bath. Forward–reverse rotation could prevent the vortex formation completely and create a strong shear stress field, which intensified the bubble disintegration and dispersion in the bath. Higher impeller rotation speed and larger blade length in forward–reverse rotation could enhance the bubble disintegration and make the dispersed bubbles smaller. The bubble dispersion zone became wider with larger blade length. The bubble size tended to be larger at higher gas flow rates. However, its dependence on the gas flow rate became smaller at higher impeller rotation speed.