THZ Detector Readout Circuit Design

Terahertz(THz) wave is in an electromagnetic wave(EMW) located between microware and infrared regions of the EMW spectrum spanning from about 0.01 mm to 3mm(0.1THz~30THz). Due to its special properties, such as low energy, high penetration for some materials and characteristic absorption by large polar molecules, THz detection and imaging technology has potential for applying in a variety of fields like disease inspection, explosive and hidden weapons detection, non-destructive detection of aircraft imperfection, and so on.In this thesis, we carried on the thorough research in the pyroelectric terahertz detection principle, and explore the pyroelectric terahertz detector design and performance testing related technologies. The main contents of the thesis are as follows:First, based on the pyroelectric effect of lithium tantalate crystal(LiTaO3), we designed a compact package, excellent signal to noise ratio of unit pyroelectric terahertz detectors. Element detector circuit adopts the model of current amplification, through the reasonable design and optimization, making the biggest sensitive element thermoelectric conversion. At the same time, the detector sensitive components and circuit structure both independent encapsulation, this very effectively reduces the electromagnetic interference.Second, we designed the 32 pixels pyroelectric terahertz line detector circuit. The circuit is 32 sensitive element output signals, which can be divided into eight groups, each group of 4 signal based on AD8627 which put chip level 3 op-amp structure, multiple signals from different door enter the same chip. Such a design makes to the greatest extent to ensure the line column amplifier circuit per the consistency of all the way, at the same time easy to late testing and adjusting, simplify the circuit line column on the printed circuit board(PCB) layout, effectively reduce the size of the circuit board. In addition, for shielding electromagnetic interference, line column sensitive element metal fixture is designed.Third, we set the terahertz line detectors related testing platform, detection unit response testing system and unit noise test system, and through the analysis of the related principle of the response voltage, as well as the results of noise power spectral density.