Design Of Photoelectric Diode Amplifier Circuit

Photoelectric detecting technique is widely used in every aspect which relates to our life closely, Such as industrial, agriculture, medical, military defense and space science and technology. In these areas Non-electric quantity information is transformed by photoelectric detector. The output signal of photoelectric detector whose property means a lot to the system is very small and easy disturbed by noise. Therefore, an effective front photoelectric detecting amplifying circuit is needed to amplify the original signal.Because it is the bridge links the the original weak signal and the latter information processing system, the design of it is significant.Photodiode amplifying circuit was designed by using the Photodiode amplifying whose type of B Series Micro FB-30035produced by The Irish SensL company. Several works have done in this paper:First, the Basic I-V conversion circuit of photoelectric diode was analyzed. So the the mutual impedance phase compensation circuit was proposed. What is more, With the deduction of the optimal calculation formula of the phase compensation capacitance and the analysis of the bandwidth of the circuit, it is discovered that the mutual impedance phase compensation circuit bandwidth has room to improve.Secondly, the basic transimpedance circuit with Phase compensation function was improved by add the bootstrap function which decreases the input capacitance of the circuit and offer a higher bandwidth than that of basic Ⅰ-Ⅴ conversion circuit.Thirdly, some improvement was applied to the bootstrap through using compound calculation amplifier and analyzing density noise spectral to deduce the optimal design formula which can reduce the noise bandwidth extremely. That is significant.Last, the actual hardware circuit was designed. To test amplifying circuit, Optical test system which is exclusively used in photodiode amplifying circuit was used. It reduces the implication of the stray light to photodiode and the interference of the environment to the circuit, therefore ensure the accuracy of the testing farthest. At last the hardware circuit was made. To test amplifying circuit, we made the Optical test system which reduced the implication of the stray light to the photorectifier and the interference from the external environment was also reduced, in this way, the accuracy of the test was ensured.Testing results demonstrated that the designed amplifying circuit meet the indicators of the front preamplifier of photodiode and offered a high Signal to Noise Ratio for the later signal to be processed by the latter circuit.