I have an application where I would like to utilize the Invert Bypassed LNA Polarity (reg 0x22 bit). I found that when I have this setting enabled and I have a Rx gain setting where the LNA is bypassed, then the RF DC offset algorithm seems to fail. The correction registers (in my case I'm using Rx 2A) in 0x176 = 0x10, 0x177 = 0x60, 0x178 = 0x80. They have these values for any gain setting where the LNA is bypassed. Basically they are railed at a high DC offset correction value.
I'm using a workaround where I edited my Rx gain table to always leave the internal LNA on, but this reduces my Rx dynamic range by about 11 dB.
Has anyone else come up with a solution that allows them to
- avoid a phase rotation when bypassing the internal LNA
- avoid corruption of the automatic RF DC offset correction algorithm
- get the full dynamic range in the receiver?