Why HMC253AQS24 needs a DC blocking capacitor，Its working frequency band includes DC？

For HMC253AQS24, all the RF pins are DC coupled. Therefore, DC blocking caps are required when the RF channel voltage is not zero.

Unfortunately, HMC253AQS24 cannot work at true DC. We are actively working on updating the legacy datasheets right now.

This seems to be the case for all RF switches of the HMC series and is quite misleading. They all claim to work from DC to x GHz (written in capital letters in the first page) and then in a small note it is written that DC blocking capacitors are required at all RFC ports.

Does this "not true DC" statement apply to all conditions, or is it juts to limit the power dissipation in presence of a large supply voltage? In my specific case I need to switch between few 50 ohm terminated 3.3V digital lines, with an equivalent maximum input power at the RFC port of 17 dBm. Are DC blocking capacitors essential?

Like I mentioned above, all RF pins are DC coupled for HMC253A, therefore the RF channel voltage is not zero and DC blocking caps are required. In your case, you still need DC blocking caps.

Generally speaking, these HMC legacy switches can NOT work at true DC, no matter if DC blocking caps are required and it has nothing to do with the power dissipation.

Thanks for the further clarification.

Then my question would be which series of Analog products replaces the HMC legacy switches. If in the RF Switches category I set FreqResp min to 0 Hz, the only products are the HMC and ADG.

The ADG series appears to have no need of DC blocking capacitors, but is only LVTTL

There is no replacement of HMC legacy switches. HMC legacy switches are still available. Meanwhile, we are developing new switches "ADRFXXXX".

I am not quite familiar with ADG series. I am copying Naveen. ndhull 

There is no replacement of HMC legacy switches. HMC legacy switches are still available. Meanwhile, we are developing new switches "ADRFXXXX".

I am not quite familiar with ADG series. I am copying Naveen. ndhull