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

414.2 The Controller DesignThe controller is design to stabilize the temperature inside the vacuum array packaging tobe at a constant temperature. A constant voltage is applied to the controller as a referencevoltage that will determine the desired temperature inside the UFPA packaging. Figure4.5 shows the block diagram of the controller loop. The output of the controller isconnected to the pulse width modulator (PMW) of the switching power supply. Thethermoelectric cooler is driven by the switching power supply to reduce the input powerof the circuit.Figure 4.5 A block diagram of the thermoelectric controller loop.The output power of the switching power supply is control by the pulse widthmodulator. The PWM produces pulses with frequency of around 20 KHz. The input tothe PWM is from -5V to +5V , and the width of the pulses are determined by the inputvoltage. If the input voltage increases, the pulse width decreases and vice versa. The