HMC311LP3

There are two compression plots in the datasheet on the third page at 1 GHz and 6 GHz. The trace does not quite reach full saturation but I would say that from these plots you are looking at Psat levels of 17.5 dBm (1GHz) and 14 dBm (6GHz). So the delta between OP1dB and Psat is somewhere between 1.5 dB an 2 dB.  The corresponding input levels to get to saturation would be approx +9 dBm (1GHz) and +6 dBm (6GHz). 

There are two compression plots in the datasheet on the third page at 1 GHz and 6 GHz. The trace does not quite reach full saturation but I would say that from these plots you are looking at Psat levels of 17.5 dBm (1GHz) and 14 dBm (6GHz). So the delta between OP1dB and Psat is somewhere between 1.5 dB an 2 dB.  The corresponding input levels to get to saturation would be approx +9 dBm (1GHz) and +6 dBm (6GHz).