THS4541: Applications that use THS4541 to reduce signal noise by reducing signal noise

Hi！Ignacio，
     Thank you very much, I also found the schematic of the attenuator, I intend to use Rf=402 Ohm, Rg=806 Ohm, but from the datasheet, the attenuation application seems to cause the phase margin at high frequencies in the Bode plot to be less than 45 degrees, and I need to use Cs as well as Cf to compensate for the zero point, but when calculating these values, since my application scenario doesn't fit any of the examples in the datasheet, I want to make sure to you if there is a problem with my parameter calculations:
1. First of all, the gain-bandwidth product given in the datasheet is 850MHz, and the unit gain bandwidth given in Table 7-2 when the gain is 0.1V/V is 457MHz, even if the unit gain bandwidth of 2V/V that satisfies the Butterworth response is also 302MHz, which is not equal to the gain-bandwidth product, then I judge that this is a multi-pole system, then I assume that the frequency of the main pole is inversely proportional to the gain, then the gain-bandwidth product is basically unchanged, Even if I have a gain of 0.5, then I should still use 850MHz for GBP (please let me know if there are any assumptions that are not valid here, because the next parameter derivations are based on this);
2. NG1=1+0.5=1.5 can be obtained from the formula of the DC_NG, and NG2=3.1V/V is also taken (here I guess that the phase margin of this gain setting is about 65, which is an ideal phase margin, so the datasheet uses this as the subject index of frequency compensation, if it is not suitable, please inform me), then my Zo is about 120MHz;
3. Cf and Cs can be obtained according to equations (16) and (17) respectively: 1.064pF and 2.234pF, because there are 0.85pF inside to form part of Cs, so the actual value of C3 should be (2.234/2)-0.85=0.267pF;
4. In summary, f-3dB=319.4MHz, and Zo=120MHz, the compensation is before the main pole;

In addition, I would like to ask if the setting of 500 ohms is only used for distortion testing, etc., for the performance test of THS itself. If I carry a SAR_ADC, i.e., drive a capacitive load, do I need an external resistor of 500 Ohm, as shown in Figure 7-11? I don't understand what the 500 Ohm Rload does at this point? Compensating for the phase? What happens if you don't use a direct break, or if you use a different value?