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
High frequency response of p-i-n photodiodes analyzed by an analytical model in Fourier space
A formulation of carrier transport in vertical p-i-n photodiodes is presented in Fourier space, taking into account diffusion effects of carriers outside the intrinsic region. High frequency response of photodiodes is investigated using the model. Calculated results show that diffusion limits the cutoff frequency characteristics of photodiodes with short intrinsic region length. Photocurrent calculations via the spectral method are in excellent agreement with two-dimensional device simulator results. The model can be utilized in circuit simulation because of its reduced computational runtime.