This work reports the development of arrays of infrared sensors (microbolometers) using a hydrogenated polymorphous silicon–germanium alloy (pm-SixGe1-x:H). Basically, polymorphous semiconductors consist of an amorphous semiconductor matrix with embedded nanocrystals of about 2–3 nm. The pm-SixGe1-x:H alloy studied has a high temperature coefficient of resistance (TCR) of 4.08%/K and conductivity of 1.5 × 10−5 S∙cm−1. Deposition of thermosensing film was made by plasma-enhanced chemical vapor deposition (PECVD) at 200 °C, while the area of the devices is 50 × 50 μm2 with a fill factor of 81%. Finally, an array of 19 × 20 microbolometers was packaged for electrical characterization. Voltage responsivity values were obtained in the range of 4 × 104 V/W and detectivity around 2 × 107 cm∙Hz1/2/W with a polarization current of 70 μA at a chopper frequency of 30 Hz. A minimum value of 2 × 10−10 W/Hz1/2 noise equivalent power was obtained at room temperature. In addition, it was found that all the tested devices responded to incident infrared radiation, proving that the structure and mechanical stability are excellent.
This paper presents the digital implementation of a double-loop feedback controller for speed and current regulation on a permanent-magnet direct current servo motor based on the real-time microcontroller TMS320F28335. The topology of the controller is based on a cascade control scheme; the speed controller (external loop) sets the reference of the current controller (internal loop). In this way, a high performance on the servo drive can be obtained. A online tuned ProportionalIntegral controller regulates the speed reference, the armature current is regulated using a hysteresis controller. In order to make comparisons a single topology speed controller (one control loop) and cascade topology speed and current controllers (double control loop) are digitally implemented. Simulation results are validated by practical experimentation. Electrical drive and sensor platform were developed for the tests. Additionally a data acquisition system is proposed.
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