The May 2013 issue of Analog Dialogue includes my article on programmable-gain transimpedance amplifiers (TIAs). Over the last few years, I have talked to several customers with different precision light measurement applications, and I decided to put this article together to summarize the most important aspects of designing a good TIA circuit. The first half of the article covers the major sources of error and the requirements for stability. The second half discusses how you can implement programmable gains within the TIA circuit, without having to resort to a second programmable gain amplifier stage. This architecture results in lower overall system noise when compared to a two-stage solution. The article goes through a real-world example using the AD8615 op amp and specifications from a typical photodiode. Finally, it goes into the details of how exactly to implement programmable gains within the TIA, while greatly minimizing the impact of having switches in the feedback path.
Please take a look at the article by clicking on the link below and feel free to post any comments about it here.