Analysis of 320X240 uncooled microbolometer focal plane array ...

45c) Heating of the TEC without heat sink.Left: Vertical scale is 200mv/block for the upper curve, 2v/block for the lower curve,and 10s/block time scale.Right: Vertical scale is 200mv/block for the upper curve, 1v/block for the lower curve,and 100s/block time scale.Figure 4.7 Step response of the TEC pump due to heating and cooling, wherethe vertical scale represents the output of the diodes and the horizontal scalerepresents time.As seen on the 100s/block time scale curve, the absence of the heat sink resulted intemperature increase inside the UFPA packaging (diode voltage drops) due to heat buildup inside the packaging. In 4.7 b), the presence of the heat sink stabilized thetemperature. In Figure 4.7 c), the effect of heating can be observed.As observed from the step response curves, the TEC pump has a time constant ofabout 20 seconds. An equivalent electrical circuit model was derived from the curves(Figure 4.8). The model is in the simplest form, and there are other more complexmodels. As shown in Figure 4.9, the model has a time constant of 20 seconds. The value