I have an application for switching 50 ohm signal at about +4dBm (1Vp-p) range 10Hz to 200MHz. I've looked at various low cost RF switch ICs offered by Skyworks , Infineon, Analog Devices. Datasheets for some GaAs FET switches say they are rated DC but still only show applications with coupling capacitors are used on all RF ports. Most RF switches are also rated minimum frequency typically 1MHz to 100MHz. I cannot find reliable information operating RF switches at DC even though in theory all these depletion FET type switch ICs should work fine at DC give correct gate biasing.
