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Photometer circuit based on positive and negative feedback compensations

Abstract:

In this letter, a linear photometer circuit based on a low-cost commercial photodiode, and both a positive feedback (PFB) compensation and a negative feedback (NFB) compensation by using an operational amplifier is presented. Here, the performance of a conventional photometer circuit based on a basic current-to-voltage converter (CVC) connection is improved by using PFB and NFB compensations, the temperature coefficient (TC) of the output voltage of such a photometer circuit is improved from -40.163 μV/°C to -21.827 μV/°C, and very high sensitivity (i.e., 3.3233 kV/W) and linearity characteristics (i.e., the non-linearity expressed as percentage of full-scale output was 0.55%) were achieved. The photometer circuit presented in this letter was used for making measurements of light at 670 nm and its response characteristic was satisfactory. Copyright © 2007 American Scientific Publishers All rights reserved.