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.

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