I'm trying to understand the FA0 and FA1 bits when the ADL5205 is used with the SPI digital interface.
The input attenuation (0 to 23 dB) and amplifier gain (14 to 26 dB) seem to be simultaneously controlled by the gain control bits (D0 - D5). Then, what do FA0 and FA1 do? This is said to control the "attenuation step size". What does that mean? Step size of what? Is this an additional attenuation level? For example, if I set FA0=FA1=1 and then pull FA_A high, is there an additional 16 dB attenuation at amplifier A's input?
I'm also confused as to the use of the term "fast attack". ADI mentions this frequently but I can't find a single definition of it. What does this mean? This appears to be ADI-specific and not an industry standard term, so an actual definition would seem necessary.