Will the LMH7220 work with a 100 MHz sine wave input between 13 - 15 dBm and DC reference at 0.8 V ?
For LMH7220 to work well, try to limit the input signal so it does not exceed the input voltage range (VRI spec) of -0.2 V to Vcc - 2 V; otherwise, the internal ESD diodes will conduct (see datasheet Figure 1: Equivalent Input Circuitry).
With 0.8 V reference voltage on IN- and max input swing of 15 dBm (~3.6 Vpp, 50-ohm load) on IN+, the negative-going swing at IN+ would try to approach -1 V but be clipped to -0.2 V by the ESD diode. A series resistor on IN+ pin could help limit the ESD diode current. To avoid clipping on the positive-going swing, Vcc should be at least 4.6 V (=0.8 V+1.8 V+2 V). Vcc of 5 V would be sufficient.
Also, be aware that there are anti-parallel diodes across the two inputs which could conduct and cause the input current above the values stated in the datasheet tables (see datasheet plot: Input Current vs. Differential Input Voltage).
Best regards,Alan