Phase shift and internal compensation capacitors behavior for Programmable Gain Amplifiers (PGAs)

Using the MCP6S91 in a design to amplify sine signals in a certain frequency range (e.g., from 10 - 750 kHz), a different phase shift is noticed, which is dependent on the gain. What are the phase shift and internal compensation capacitors behavior for the chip?

The datasheet has a table, GAIN VS. INTERNAL COMPENSATION CAPACITOR (Table 4-1), that shows how bandwidth changes with gain.

The Gain Bandwidth Products (GBWP) shown in the datasheet gives a general indication of this part's compensation. The plot in Figure 2-25 (Gain vs. Frequency) shows the magnitude response over frequency. The bandwidth (BW) changes with gain. Also, the response shape changes with gain, which indicates the phase response will include multiple pole and zeroes. This means the BW information in Table 4-1 is not adequate to predict the phase versus gain behavior of this part. The workaround is to measure the phase versus gain in conditions of interest and use those results as an indication of typical behavior.

​

The MCP6S91 datasheet can be viewed and downloaded from the product landing page.

  Return to Top

© 2024 Microchip Technology, Inc.
Notice: ARM and Cortex are the registered trademarks of ARM Limited in the EU and other countries.
Information contained on this site regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer's risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights.