High Performance Analog Front End Interfacesのトピック#NAFE73388 Gain setting beyond 3.2x

#NAFE73388 Gain setting beyond 3.2x

Arvind_Srinivasan — Sat, 21 Mar 2026 07:31:15 GMT

NAFE 73388 has limitations on maximum gain settings via configuration register to either 0.2x, 0.4x AND 0.8X

Based on the calibration coefficients and configuration registers for NAFE 73388, maximum possible gain is 4 times at 0x FFFFFFFF. So, setting a default gain of max 0.8x with calibration coefficient gain of 4 times leads to a max gain of 3.2x which is still well short of 4x, 8x and 16x claimed in the datasheet of NAFE73388. How to push beyond this max limit of 3.2x.

NAFE13388 has gain settings of x4, x8 and x16, but the shipped EVAL board with the provided GUI testing utility itself fails beyond gain of 0.8x for differential mode and 4X for single ended

Re: #NAFE73388 Gain setting beyond 3.2x

RafaR — Mon, 23 Mar 2026 21:09:01 GMT

Hello Arvind_Srinivasan

Good Day!

I think there was a confusion, the x4 / x8 / x16 gains that the datasheets promise come from the PGA gain setting (an analog block), not from the digital calibration multiplier. If you only touch the “0.2 / 0.4 / 0.8” options, you are staying in the attenuation modes of the PGA and will never see >1× before calibration. The fix is to put the PGA into its gain modes 1,2,4,8,16

I recommend that you reread chapter 7.3.3 Programmable gain amplifier

I hope this information has helped you, please let me know if you need help with anything else.

Have a great day and best of luck.