Digital control of TGC via SPI intended for fixed attenuation/testing. Analog control TGC is piecewise linear but it is possible to specify the timing of uniform and non-uniform time gain control using programmed settings on our AFE5801, AFE5851, AFE5816, AFE58JD16 devices.
https://e2e.ti.com/support/applications/medical/f/30/t/531483