PIN?

I don't think I'd use an LED. Direct bandgap semiconductors such as GaAs tend to have minority carrier lifetimes on the order of 1 ns, which is quite a bit less than you need for low-distortion RF switching.

Photodiodes tend to die if you run them at any significant forward bias, because they use a thin epitaxial layer and have metal contacts only round the edges, which leads to huge current crowding if you apply forward bias. I'd tend to look at low current, high voltage rectifiers instead.

Cheers,

Phil Hobbs

PIN diodes have a relativly long intrinsic(undoped) region between the oppositely doped ends with two small SCLs. When they are reverse biased, the capacity is very low and they can stand a high reverse voltage. forward biasing creates minority carriers injection into the intrinsic region, which have long life-time and thus give a resistive character for higher frequencies, depending on the DC bias. I do not think any other diodes have this behaviour.

A 1N4007 has been used as an PIN diode for switching RF.

kevin

In a bridge configuration almost any diode will work, including handling RF power.