• Media type: Text; E-Article
  • Title: In-circuit-measurement of parasitic elements in high gain high bandwidth low noise transimpedance amplifiers
  • Contributor: Cochems, Philipp [Author]; Kirk, Ansgar T. [Author]; Zimmermann, Stefan [Author]
  • Published: College Park, MA : American Institute of Physics (AIP), 2014
  • Published in: Review of Scientific Instruments 85 (2014)
  • Issue: published Version
  • Language: English
  • DOI: https://doi.org/10.15488/4415; https://doi.org/10.1063/1.4902854
  • Keywords: Analog circuits ; Operational amplifier ; Oscilloscopes ; Parasitic capacitance ; Laboratory equipment ; Signal generators ; Transistors ; Alloys ; Measuring instruments ; Transimpedance amplifiers
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  • Description: Parasitic elements play an important role in the development of every high performance circuit. In the case of high gain, high bandwidth transimpedance amplifiers, the most important parasitic elements are parasitic capacitances at the input and in the feedback path, which significantly influence the stability, the frequency response, and the noise of the amplifier. As these parasitic capacitances range from a few picofarads down to only a few femtofarads, it is nearly impossible to measure them accurately using traditional LCR meters. Unfortunately, they also cannot be easily determined from the transfer function of the transimpedance amplifier, as it contains several overlapping effects and its measurement is only possible when the circuit is already stable. Therefore, we developed an in-circuit measurement method utilizing minimal modifications to the input stage in order to measure its parasitic capacitances directly and with unconditional stability. Furthermore, using the data acquired with this measurement technique, we both proposed a model for the complicated frequency response of high value thick film resistors as they are used in high gain transimpedance amplifiers and optimized our transimpedance amplifier design.
  • Access State: Open Access